Document Oz1Npj1zb47oZeBLp6ebzgKYp

TEE MANUFACTURE OF KATLO PRODUCTS by V. C. Taylor r \ { June 10, 1959 01 062 o DISTRIBUTION RESTRICTED TO: Mr. E. S. Adans - Toledo Dr. L. P. Biefeld - Toledo Hr. B. E. Boyd - Toledo Mr. J. H. Briley - Toledo Hr. P. B. Brown - Newark Mr. F. R. Conrbe - Kansas City Hr. R. S. Grant - Toledo Hr. C. 7. Handel - Toledo M. L. R. Kessler - Toledo Mrl R. J. Faolettl - Barrington Hr. A. J. Pearson - Newark Hr. 0. V. Pfeifer - Berlin v w. K. Sidwell - Toledo (6) Dr. A. C. Siefert - Newark Hr. A. L. Sinison - Toledo Hr. H. V. Snith - Toledo Hr. C. A. Snneker - Newark Mr. G. C. Stefango - Toledo Dr. W. c. Taylor - Toledo , u-- E. J. Walker - Toledo Hr. P. L. Welsh - Newark 01 0G2 0rS5 ( Preface The purpose of this manual is to serve as an aid to good practice in the manufacture of Eaylo products, and to provide irf creation to those who nay not be familiar vith the nature of the operation. The material contained herein is the result cf both laboratory research and plant experience over the years. Admittedly, sene of what is written nay still be classed as theory, and sene statements nay even be considered as controversial. There remains much to be learned. The manufacture of Kaylo products is still a relatively new and "green" industry. This is probably all to the good, because when seething is no longer green it stops growing and rot begins. Kai^, many persons have contributed to our present state of taovledge on the subject. This manual represents an effort on the part of the author to correlate and integrate the information available at this time. . It is not the intention here to describe in every detail, and step by step, the various aspects of a prescribed operation. This has been done in several manuals written by members of the staff at the Berlin plant. Rather, this manual is designed to attempt to explain why certain things are done as they are cr wny certain changes in operation are indicated. 01 0G2 ^. \ f THE MANUFACTURE OF EATLy PRODUCTS contents Chapter Page I. TrZ NATURE cf ratio PRODUCTS.......................................................... 1 II. TIFFS OF XA.TLO PRODUCTS................................................................... U m. FORKUUTIOMS......................................................................................... Fcmuiation for Kaylo-10 Insulation.............................. Formulation for Kaylo-10 Cere Material............................... Formulation for Kaylc-20 ThermalInsulation..................... Formulation fer Xaylo-20 Cere Material............................... 6 7 8 9 11 17. ROLF CF TPZ VARIOUS RAW MATERIALS............................................. Asbestos. ..................................................................................... .... . Chrysotlle........................... *............................. .............................. Anosite.............................................................................................. WojJLastonite................................................................................ . . Line........................................................................................................... Quickline......................................................................................... Kycrated Line................................... Silica...................................................... ............................................. Tripoli ......................................................................................... Celaton (Daatcnaceous Earth)................................................. Clay........................................................................................................... Inert Ingredients............................................................................ Ground limestone. ....................................................................... Chrcnite............................... Surface Active Agents Tanol #711......................................................................................... Coloring.................................................................. Red Iren Oxide......................................... ... .................................. 12 12 13 11 16 17 17 18 IQ 18 IP 20 20 21 22 22 22 . 22 22 V. RAW MATERIAL SPECIFICATIONS.......................................................... Chrysotlle Asbestos . .............................................. .... . . . Anosite Asbestos. .................. Pulverized Quickline....................................................................... Hyorated Line Tripoli......................................... *.................................................... Diatoo&ceous Earth* ................. Clay....................................................................... Limestone Flour........................... .... ............................... . Iron Chrcnite . Woilastonite Rea Iren Qxiae ............. ...................... Dispersing Agents 23 23 2k 2U 25 25 26 26 27 27 27 28 28 71. BATCPZNG AMD MIXING OPERATIONS................................................. 29 01 062 oasn Chapter I CF KAXLC frcdvjcts Kaylo is a registered trade mark employed to specify the hydrous calcic silicate products manufactured by Owens-Ccming Fiherglas Corporation. Kaylo is an adjective and should never be used as a noun. Furthermore, it should always be capitalized. As just mentioned, Xaylo products fall within the class of materials <cown as hydrous calcic silicates* Research over the years has revealed the existence of a large ntrsber of hydrous calcic silicates, but the majority of these are scarcely more than laboratory curiosities. That is to say, little or no use is known at this tine for many of these compounds* The term hydrous calcium silicate denotes a chemical compound composed of CaO Cline), Si02 (silica) and H?0 (water). A specific hydrous calcium silicate has, of course, definite physical and chemical properties. The formation of hydrous calcima silicates can be effected in one of two ways: 1) By the reaction of water with previously formed anhydrous calcium silicates, such as occurs in the hardening of Portland cements when mixed with water? 2) The direct union of CaO, Si02, and K2O. It is this method that is employed in the manufacture of Kaylo products. The two hydrous calcium silicates that are of interest in connection with Kaylo products are: tobemorite, having the formula hCaO.52iO2.5K2O? and xcnotlite, having the formula 5CaO.5SiO2.HoO. Other hydrous calcium silicates can be* and sometimes are, present in Kaylo products. But the majority of these are of an accidental nature, and most are detrimental for one reason or another. Tobermorite, like so many minerals, can accommodate varying amounts of other constituents within its crystal structure. This, when controlled, can be used to an acrantage. More will be said of this later. Xonotiite apparently shows no tendency to incorporate any "foreign" oxides within its structure. In the formation of hydrous calcium silicates by hydrothermal methods, the lime apparently first reacts readily and completely with silica to form lime-rich calcium silicate gels having variable compositions but characterized by C&0/S102 ratios in excess of unity. These products in turn react with residual silica of the mix to fora products poorer in lime* The order of formation and transformation is believed to be thus: lime-rich gel -->5Ca0.hCa0.nH20--^CaO.SiC^.n^O--:7hCaO.5SiO2.nH2O--^ hCaO.5SiO2.5H3O (tobemcrite). To achieve the desired end product in the above progression, it is necessary to have the proper batch, ratio of line and silica in such form as to be reactive under conditions of the process, and to permit suffi cient time at a given temperature (pressure). If appreciable amounts of the intermediate products are present, the ware wili show such undesirable properties as: high shrinkages upon drying, punky structure and lew ^ a strength, and/cr high shrinkages at elevated temperatures. " 1 vua Ur 2 If the batch ratio or lime to silica is near unity, and if s'lfficier.t tine is permitted at temperatures and pressures in excess of about 300F and 52 psig, respectively, the reaction given above will continue as: hCaO.SSiQ^SKjO--' 5CaO.5SiO3.H2O (xonotlite). The composition of the intermediate product In the transformation of tobermorite to xonotlite has not been fully resolved as yet. X-ray diffraction patterns generally shov some lines characteristic of the two eni members, but certain other key lines may be missing. Relative intensities may also vary. It is generally the practice to refer to this intermediate product as "hybrid" material. - The advantage that structures of xonotlite have over those of tobernorito is higher temperature resistance. A structure of the hybrid material is intermediate in this respect. ' The possibility still exists, however, that tobermorite is transformed directly into xonotlite, and the hybrid material Is in reality a mechanical mixture of the two. In any case, the effect Is the same. As mentioned earlier, tobermorite can take certain other oxides Into its structure. Alisina, AI2O3, in particular enters the structure readily. When this occurs to any appreciable extent, the transformation of tobermorite to xonotlite Is retarded greatly; so much so that for practical purposes it may be considered as preventing the transformation. Because of this, batches intended for the production of xonotlite must be free of any sub stantial amount of reactive 11203. On the other hand, tobermorite containing AI2O3 Apparently forms more readily than the pure compound, and also yields ware of higher strengths. However, high temperature resistance of the ware f Is decreased roughly in proportion to the amount of 11303. But it Is possible to take advantage of the favorable characteristics Imparted by - a limited amount without the temperature resistance being lowered to a point that is critical for most Installations of the product. The positive identification of the various chemical combinations or phases, either desirable or undesirable, that can e:dat in hydrous calcium silicate products is not easy or simple. Generally, in other systms, products are fumed which are readily discernible by means of the light microscope. Accordingly, optical properties and other characteristics can readily be determined. Because the crystalline products that are formed within reasonable times by hydrothermal means in the lime-silicawater system are so extremely fine, identification is not possible with the light microscope. Other means, such as X-ray diffraction and differ ential thermal analysis in particular, must be employed. Less certainty of positive identification results. Furthermore, the extrete fineness of the crystalline oenpounds results in behavior often more typical of & gel rather than a crystalline structure. In these cases, the water content and the distribution of this water throughout the structure hpr$ a distinct effect on the properties of the product. . Because of the above circumstances, it 1s the more eemmon practice to attempt corrective measures based on certain assumptions as the cause of ware being off quality,- rather than on the results of extensive labora tory tests. That is to say, diagnoses are often made without supporting laboratory data. In plant operation, time is all Important and cures 01 0G2 0A2R f must be effected la the shortest possible tine* It is not intmded to isply that these assertions are nere guesses and vitheut foundation* They are made by trained personnel and are based on the findings cf past research and plant experience. It is being erphasised that considerable art is involved in the manufacture cf Xaylo products, and successfuloperations are largely dependent upon the presence and decisions of persons thoroughly trained in the art* 1 062 09o / f \ ( u Chapter II TTPZS C? KA.HO PHOICCTS In the previous chapter, it was pointed cut that Kaylo products consist essentially of hydrous calcita silicate* The true density of these silicates is about 150 pounds per cubic foot. In fact, the cver-ali density of the constituent solids of Kaylc naterials is about this value. The apparent density, which is considerably less, is determined and controlled by the ratio of water to solids erpieyed in raw batch. 3y means of the proper selection of amounts and types of asbestos, together with further fiherization, dilute suspensions or slurries are obtained which do not settle or lose water by bleeding. Prescribed treatment is also followed in the hydration of the line tc assist in obtaining these stable suspensions. With slurries of this nature, the volume of the hardened body is sensibly the same as that of the cast slurry. When the water is removed by drying from the interstices of the solid framework of hydrous calcium silicate that has been formed in the process, a pro<ict of low apparent density results. It is obvious that the higher the ratio of water to solids in the slurry, or the greater the percentage of total voice con tributed by the water, the lower the apparent density of the product after the free water has been removed by drying. Xnasuck as the synthesis.of hydrous calcium silicates is involved, some water of the batch becomes fixed in that it beccrces an integral part of the compound in question. Put this amount represents a very **m*''i percentage cf the original volume. The chief products of the Berlin plant are generally considered as being of four types; characterized by two different apparent densities for each of two different hydrous calcita silicate compounds that con stitute the structure of the product. ' As mentioned in Chapter I, the two hydrous calcium silicates of interest in.connection with Kaylo prooicts are to'oemorite, hCaO^iOj.SHjOj and. xonotlite, SCaO.SSiOg^HgO. The tooemcrite-type products are referred to within the organization as Kaylc-10, K-10, or regular Kaylo. In the literature Kaylo alone is employed; the products being called Kaylo Pipe Insulation, Kaylo Block Insulation, or Kaylo Core Material. The Pipe and Block Insulation have a nmirmi. apparent density of ll.li pounds per cubic foot, and the Core material 20.0 pcf Thus, the two classes of Kaylo-10 products are distinguished from each other by their difference in apparent density and their end use. The Kaylo-10 products of the lighter density are designed primarily to afford thermal insulation at elevated temperatures up to 1200F, whereas the purpose of Kaylo-10 product of the heavier density is to .provide a structural material whose strength and fireproof nature together with its insulating value, make it highly desirable as the core of panels and doors of sandwich-type construction. The facing material that is applied by the customer may be wood, metal, transite, etc. 01 0G2 0<5QI r> Kaylo-20 ware is characterized by having a xenetlite, SwaO.JSiC^.HgO, structure. Included are Kaylo-20 Pipe Insulation and Kaylo-20 clock Insulation haring a nominal apparent density of 12.5 pounds per cubic foot, and K-20 Cere Material at 20.0 pcf. Similar to the Kaylo-10 ware, the end use of the Kaylo-20 products dictates the production of two different densities. The advantage of Kaylo-20 ware in each case is its higher temperature resistance, the licit being 1300?. instead of 1200F. The apparent density of the product in ary case is chosen to yield a material haring a hardness and strength demanded in its end semes, or, as is the case with Kaylo-20 thermal insulation, is the natural result of the water/solids ratio required to gire stable, non-settling slurries. In no case is a higher density eaployed than is considered to -be a safe minimum under the circumstances. The strength of both Kaylo-10 and Kaylo-20 products expressed as modulus of rupture tends to vary roughly as the square of the density. For example, the modulus of rupture for Kaylo-10 thermal insulation at 11.U pcf density nay be expected to be about 75 psi, and that for Kaylo core material at 20 pcf density is likely to be about 230 psi; 75 x (20)2 - 230. arnrj2 A modulus of rupture of about n? psi is not uncommon for Esylo-20 insulation of 13 pcf density, and about 265 psi can be expected for Kaylo-20 core of 20 pcf density: - 112 x (20)2 - 265. TIIT2 Theoretically, for a given density the Kaylo-20 material probably should not be quite as strong as the Kaylo-10 prodset. The reason for this is that the structure of the former is more coarsely crystalline presents less area of contact for the cohesive forces. Actually, however, in ccrmercial production the reverse tends to be true in respect to modulus of rupture. The likely explanation is that Kaylo-20 material, being composed of crystals of greater sine, behaves less like a gel and is more stable In the drying process. During the drying of Kaylo-10 ware, stresses are likely to be created and result in incipient cracks which adversely affect the tensile strength. Compressive strengths on the other hand, are not as seriously affected by these flaws in stractures, and for a given density are generally higher for Kaylo-10 than Kaylo-20 insulation and core material; It should be emphasized that these strength data represent general values and trends. A number of factors greatly affect the strength. These are discussed at greater length in a subsequent chapter. 01 0G2 0ZPSi 6 Chaster III F05KUL less A maber of things have to be taken into consideration in desiring a formulation for a given type of Eaylo product. Perhaps of utmost impor tance is the combination of properties in the end product. Among these for the real insulation are: modulus of rapture, compressive strength, hardness, handleability (resistance to abuse), apparent density, appearance, shrinkage at elevated temperatts'es, and therr.al conductivity or "k" factor. It so happens that the octants or ideal cannot be obtained for each and every property, at least at this tine. A sacrifice in one is frequently Bade to benefit another. For example, the aeans that have been employed to bring about a reduction in "k" factor have resulted in sene loss of strength. Efforts, then, are directed toward the attainment of the best combination of properties that are possible, as indicated by customer reactions. lie design of a formulation is further ccnplicated by the fact that a slurry Bust result which can be bandied nost satisfactorily by existing plant methods and equipment. Furthermore, the fcmulaticn must lend itself to the greatest possible speed of processing throughout the various steps Xrcn mix to tria. Here again a compromise must be Bade between one or more of the desired properties and the ease or speed of processing. A case in point: it is known that shrinkage of the product at elevated teperatures can be reduced by employing less dlatcsaceous earth and nore crystalline silica, but it is also knevr. that the rate of prehardening would be lowered and longer periods of autoclaving would likely be needed. " Further complications are introduced by efforts to keep batch costs as low as possible. The effects of a substitute material, an additional constituent, or a change in density, have to be carefully observed and analyzed to determine if the change has been favorable in respect to .speed of processing, quality of the product, and the amount of off-ware. An addition to batch cost nay in effect represent a saving in the long run. 01 062 0&93 ( l Frrrml-a-tiea for Karlo-10 Insulatian The following femulation is currently (March, 1?5?) c ployed fcr ' Xaylo-10 pipe covering and block, ana has been ir. use since December, 1: Raw Material Weighed Amount (Pounds) Dry Weight (Founds) Fercem AW anosita asbestos 100 100 3.2S W-3 aaosite asbestos 50 50 1.61* 6D chrysotile asbestos 150 150 h.92 IS chrysotile asbestos 200 200 6.56 Quickline 82x0 81x0 27.55 Tripoli Celatca 350 350 H.iS 850 816 26.76 Clay 100 100 3.28 Gronad limestone Air-float chrasite Wollastonite C-101 21x0 100 100 2h0 7.87 100 3.28 100 3.28 Tasol #731 Totals 12.5 3 3,0ix9 0.10 100.00 Water - 16,830 lbs* Water/solids - 5*53 Molar Ca0/Si02 .77 Factors: CaO/quicfclAae - .91* S102/CelatCD .83 SI02/tripoli *99 SiOg/clay - .1x5 01 062 0599 8 At the tire of writing, there are no basic changes indicated in formulation. There is, however, continuing search for ingredients that would lower tie nkn factor of the product without necessarily *-*>*?-; part in the chemical reactions involved in the formation of the desired procuc If such an ingredient is found, the amount employed in the formulation v:___ in all probability be ainor in respect to the line and siliceous materials. r4> Arrangements are underway to conserve the slurry carried by the water in the periodic wash-out of the sixers and lines, and to return this diluted slurry to the batch* It is also proposed to return at least a significant portion of the waste Kaylo material resulting from trim and off-ware to the batch at the-earliest possible date. Certain adjustments will be made so that the proportions of the solids to each other and the ratio of total soldds to water do not differ from those in the formulation given above. Formulation for Kavlo-10 Core Material Given below is the formulation employed in the manufacture of Kaylo-10 Core Material* It is sometimes referred to as Hydrate Cere to distinguish it from another type of Eaylo-10 core produced earlier. Raw Material Weighed Amount (Pounds) Dry Weight (Pounds) Fercen' 6D chrysotile asbestos 150 150 h.ll hT chrysotlle asbestos 300 300 8.23 Rydrated lime 1,800 1,386 38.02 Tripoli Celatcm Clay Totals l,h00 575 50 l,ii00 360 ____50 3.6U6 38*hO 9.87 1.37 100.00 Water - 10,200 lbs. Water/solids - 2*91 Molar Ca0/Si02 - *82 Factors: CaO/Hydrated lime * .73 SiOo/Celatcsn .83 SiOj/tripcli *99 SiO^/clay * .h5 01 062-05^5 ( \ 9 This formulation yields a product that is satisfactory as to strength, but the ware is often subject to drying cracks in the process. The formu lation for Kaylo-10 core material should be the object cf further study* The writer feels that sere reinforcing, either asbestos fibers or the fibrous wollastonite C-1C1, should be employed* It is also felt that an improved product would result under conditions cf practical autoclaving cycles if the molar Ca0/Si02 ratio were to be lowered to about 0.75* It will be observed that hyurated line instead of quicklime is used* This is done to keep the consistency of the slurry low enough for it to be handled satisfactorily in the casting operation* It would be acrantageous if quickline could be employed* Hydrate is more eersive for a given CaO content, deteriorates much more rapidly, and represents an additional raw material to handle in the plant. Perhaps sene combination of asbestos and wollastonite C-101 can be found that will provide adequate reinforcing and will contribute less to the consistency of the slurry, so that quicklime can be used for the Kaylo-10 core formulation* - ' * Formerly, a Kaylo-10 cere material that was satisfactory in most respects was made frea a formulation in which portland cesent supplied most cf the line and silica. It had been designed to fit into the Sayreville operation, which required a very rapid rate of prehardening. Early in July, 1?57, complaints were received fren a customer stating that Kaylo-10 core exhibited greater absorption cf the adhesive in the laminating operation than a competitive calcic silicate cere material. The change to the above hydrate formulation in July 1957, resulted in a material shawis^ considerably less absorption of glue, and equal to competitive material in this respect. Formulation for Kavlo-20 Thermal Insulation At the tine this is being written, there are two schools cf thought in regard to the optinmi formulation for Kaylo-20 thermal insulation. Both groups can present data supporting their contentions. Scae feel that the ' 1.017 molar Ca0/Si02 ratio of the formulation currently employed is too high for the amount of antoclaving pemissable at present rates of production* Others are of the opinion that the great quantity of excellent ware produced from formulations having this CaO/SiO? ratio indicates that it is satisfactory. The writer-is inclined to feel that the 1.017 value represents yust about the maxinun, and if for sene reason the ware does not receive the customary amount of autoclaving (the prescribed tine, pressure, and teperatare)', higher than normal amount of shrinkage at 1800F will likely result. For this reason, he feels that a molar ratio of about 0.95 would prove more satisfactory day in and day out. \ X- \ 01 062 0 10 Following is a formulation typical for the production cf Kaylo-20 thermal insulation* The actual quantities vary depending upon the amount of slurry required for the particular train of molds to be filled, but the re2 rtive amounts of the ingredients are held constant: Bav Material W-3 amosite asbestos 6D chrysotile asbestos kK chrysotile asbestos Quicklime Tripoli Bed iron oad.de Weight (Pounds) 375 150 50 1,025 1,025 11 reruer.t 13*00 5.20 1.73 35.52 35.52 0.38 Wollastonite P-1 Totals 250 2*886 8.65 100.00 Water - 13>515 lbs. Water/solids - U.71 Holar Ca0/Si02- 1.017 Factors: CaO/quicklime - ,9h Si02/tripoli * .59 It is possible that an inert ingredient may be added in the future to function as an opaeifier to infra-red rays. Kaylo-20 thermal insulation is designed to serve at temperature ranges where radiation is an important factor in the conductance of beat. Extremely finely ground zircon is an example of a material that exhibits some opacity to infra-red. k trial run of Kaylo-20 thermal insulation containing $% of zircon is awaiting test. 01 0G2 0,377 Formulation for Kaylo-20 Core Mater4-*-! As is the case v-'.th Kaylo-20 thermal insulation, there is also a difference of opinion as to the best solar CaO/Si32 for Kaylo-20 core* The ratio was reduced to *577 froa 1*00 in December 1?58 with results that are not too clear cut* It is the writer's opinion that this ratio is still scaewhat on the high side to be safe for plant production* In the current formulation given below, the computations are based on a CaO content cf 72% fcr the hydrate. If by charge the CaO content fcr the lot actually used was 7h% instead of 732 as found in the test ssaple, a molar Ca0/Si02 ratio of ,99 vould obtain* The hydrate content is varied in acccrd with the amount of available CaO found to be present in the test samples* The following batch is based on a 732 CaO hydrate* Eav Material Ve:Ighed Amount (Pounds) Dry Weight (Pounds) Pereen LI chrysotile asbestos 550 550 11.83 Hydrated lime 1,580 1,1*8 39.06 Tripoli Bed iron cTida Wollastonite P-1 1,520 15 175 1,520 *15 175 kO.99 O.hO h.72 Totals 3,708 100.00 Water - 10,005 lbs* Water/solids * 2.81 Molar CaO/SiOg - .577 Factors: CaO/hydrated lime *73 Si02/tripoli - .99 - 01 062 0398 Chapter 17 ROLE 0? THE VARIOUS RAW MATERIALS . Asbestos The term asbestos is not definitive of an7 specific cheiisal compound. It is a general term applied to any natural mineral that tends to occur in a fibrous form. Throughout the years, various minerals in this fern have been tried in Kaylo formulations, but only two, chrysotile asbestos and amosite asbestos, have proved to be satisfactory quality-wise, or to be economically feasible. Asbestos is employed for two purposes. First, it is an effective suspending agent. With proper fiberizstioa, it is possible to obtain stable, non-settling suspensions of as little as 3 or Li of asbestos in water. This Jackstraw arrangement of fibers is capable of supporting and keeping other solids frcm settling out of suspension in dilute slurries. It makes possible the creation of the stable suspensions of high water content necessary fcr the production of lightweight products by our present process. Second, asbestos fibers provide reinforcing. They not only tend to prevent cracks from originating, but they also tend to held the piece together after a crack has occurred. The latter faction is ccmmonly referred to as hinging.4 As recently as 1939t the role of asbestos as a reinforcing material was not appreciated, and it was even later that asbestos was employed to . nake light density products possible. The first hydrous calcium silicate products manufactured were of relatively heavy density. They were found to he subject to severe cracking, and even to disintegration with tine when exposed to even moderate temperature changes, and to changes in h^idity. The cementitious phase of Eaylo-10 products is essentially tobemorite. While this compound is crystalline, the crystals are so extremely fine' that the structure tends to behave as though it were a gel. That is to say, there is significant swelling or shrinking with changes in moisture content brought aheut by change in surroundings. Reinforcing in the fora of asbestos is necessary to stabilize this gel-like structure. On the other hand, Kaylo-20 products are composed of xonotlite. This material is more coarsely crystalline and the crystals themselves are needle-like. Heavy density Kaylo-20 products are not subject to the cracking tendency exhibited by Kaylo-10 ware. Attempts have been made to substitute other fibers for asbestos in varying amounts. Glass fibers of alkali resistant compositions have been tried and these failed on two counts. In the first place, contrary to the' behavior of asbestos, they tend to clump and ball-up, instead of becoming evenly dispersed throughout the slurry with aisng. In the second place, even the most resistant glasses exhibited an envelope of altered glass about the fiber* As a consequence, a satisfactory bond did not obtain between - the hydrous calcium silicate and'the unaltered portion of the glass fiber. 01 0G2 08Lfl Uj Piberized bagasse has also been tried without success* This organic material undergoes sane shrinkage in the processing and vithdravs from intimate contact with the cementitious phase, rending it cf little use as a reinforcing fiber. Limited amounts of the fibrous mineral vollastcnite are new being used for reinforcing in certain formulations. More will be said cf this later. Chrysotile Chrysotile asbestos is essentially hydrous magnesia silicate of the same chemical composition as its mother rock, serpentine. The pure mineral has the formula 3KgO.2SiO2.SH2O, cut ccsraercial fibers invariably contain varying amounts of other oxides as impurities. Chrysctile is rather widely distributed, but about 60? of the world's market is supplied by Canada and about 20? by Russia. Host of the chrysotile coming from Canada is graded and labeled according to a uniform system which is universally recognized. The grading systea is arranged to divide seven main groups of asbestos into mere than twenty- five grades. Standardisation of the various grades is produced and main tained by regular testing on the Quebec Standard Testing Machine. This equipment consists of a nest of 3 screens and a pan measuring 2byr lh-3/liux bn deep, resting on a table which is movable and is driven by an eccentric rotating in a vertical plane at 328 rps. The screen sizes are 2, h, and 10 mesh, respectively. L timing device alleys exactly 600 revolutions per test. Testing is done on a 16-ounce sample representative cf the lot. The sample is divided into four fractions by the action of the testing machine. The weights in ounces of the fractions retained on each of the three screens and that caught in the pan are recorded. These weights define the quantity of the various fiber lengths in the sample, and in this manner establish a certain grade. The greater the proportions of longer fiber, or the greater the amounts on the coarser screens, the lower the number designation of the grade. Within the numerical grade there is also fc*ther gradation defined by a letter of the alphabet; the lower the letter in the order of the alphabet, the greater the proportions of the longer fibers. Chrysotile fibers tend to be relatively short. The price increases rapidly with increase in fiber length. Certain grades of long fiber may sell for considerably more than a thousand dollars per ton. In Kaylo formulations, grade UK and grade 6D are currently used. The delivered prices are about $226 and $102 per ton, respectively. The distri bution of the fibers in these two grades are: On #2 mesh On h mesh On #10 mesh In Pan UK 0 6D 0 k 0 93 79 01 062 0300 iu Chrysotile of good quality is a soft, yet strong fiber. The individual fibers of a given grade are in reality bundles of much finer fibers. As such they hare fine "hairs" pro .ruling from the sides, and tend to exhibit broomed ends. It is this rtake-up that is responsible for their remarkable ability to stay in suspension, and to support other solids in dilute slurries. This structure also tends to hold vater vithin it, and imparts non-oleeding characteristics to a slurry. The difference in structure between chrysotile and glass fibers accounts for their different behavior when incorporated in slurries. Although the grading and labeling of Canadian chrysotile is rigidly controlled, there are differences in quality of supposedly the sane grade from different sources, as far as being an ingredient in Kaylo products is concerned. The various chrysotiles cay differ in suspending power, a-d differences in inherent strength nay be reflected in differences in strength of the vare. The only means isiown at this tine to detect these differences is in the'testing of the resulting Kaylo slurries and products. To date no Canadian chrysotile has proved as satisfactory as that of J-H. However, the search is continuing, and it is likely that other sources of supply will be found* The Canadian systei cf labeling does not necessarily apply to chrysotile free other countries* As a rule, samples of the various grades sust be obtained and attempts cade to classify then on the Canadian basis before choices are cade for trial Kaylo batches. United aaounts of Venezuelan chrysotile have been used vith success when blended with J-H aaterial* It is questionable that it could be used to the exclusion of the latter* As mentioned above, chrysotile is a hydrous compound. That is to say,vater is an integral part of its crystal structure* For this reason it begins to disintegrate and lose strength at relatively low tenperatures in terms of thermal insulation* As recently as 1955t chrysotile was the only type of asbestos employed in Kaylo thermal insulations* The demands of the trade for greater stability at higher temperature, and for reduced thermal ccnductivuty, led to the use of a blend of aaosite asbestos with chrysotile in Kaylo thermal insulation* Amosite . Amosite is essentially an anhydrous ferrous silicate. When pure it has the formula, Fe0*Si02* Usually there is some KgO in the structure, along with a little CaO* The fibers tend to be very much longer than those of chrysotile* For the grades used in Kaylo batches, a large percentage of the fibers'are longer than one inch, with some ranging up to about three inches or more* Almost all of the fibers are longer than 3/8" The delivered prices at Berlin for these fibers are about $196 to $210 per ton. In com paring these prices with that for UK chrysotile, it is eviosnt that a fiber of much greater length is obtained at a somewhat lover cost* Africa is the only important cccsercial source of aaosite 'asbestos. Each producer, who may buy crude,-from many sources, uses his own system of nomenclature for the various grades. Aside from fiber length, the quality of amosite in respect to strength, brittleness, gangue content, etc., may vary 01 062 0.30/ \ r/ 15 greatly from vender ^o vendor. Prices fer material cf the sane quality nay also vary considerably. However, it has been found that the quality has regained quite constant of given grades supplied by North American Asbestos. Prices also have compared favorably. From what has been learned, ve presently appear to be in a position of a preferred customer of North American. As mentioned above, amosite is an anhydrous compound, which means, of course, that it contains no water as part of its structure. Partially for this reason, it can withstand higher temperatures than can ebrysetile before breakdown begins. The substitution of ancsite for chrysotile results in products having lower shrinkages at elevated temperatures. Another factor in favor of anosite is that lower Bk factors, particularly at higher mean temperatures, result in the products when it replaces chrysotile. This is believed to be due to the fact that it is an iron compound and as such is more effective in blocking infra-red radiation. Seme of the ferrous iron of the amosite apparently undergoes a base exchange with the lime of the batch, and becomes disseminated throughout the entire hydrous calcima silicate structure. That the entire body of the product becomes uniformly pink after being subjected to high t^peratm-es is evidence of this. laylo products containing only chrysotile remain white. Just how much iron and line are involved is not imewn. A study of this phenomenon would be most worthwhile. If the amount of line that takes part in this reaction is significant, and if line is thus prevented from combining with the silica to form hydrous calcium silicate, the true CaO/SiOg ratio may be different from that designed and intended for the formation of the desired hydrous calcium silicate. Still another argument for the use of a certain percentage of the asbestos as amosite, is the pouring characteristics imparted to the slurries. Being a stiffer fiber, its presence makes for a slurry less prone to result in eddies as it is being cast into the molds by present methods. This differ ential movement within the slurry, with one portion sliding over another, results in slip planes or discontinuities within the ware. On the other band, too high a proportion of amosite results in a "harsh*1 slurry vhich tends to fold or tear as it is being cast in the mold. These patterns are carried over into the finished ware as defects. While high amosite contents may yield a slimvy that holds the solids well enough, this stiff and relatively open framework of fibers may permit the loss of water by bleeding. Consequently, a blend of amosite and chrysotile is employed in the production of Kaylo thermal insulation to take advantage of the favorable characteristics of each. However, in a process that does not involve the holding of the slurry for any length of time under quiescent conditions, bleeding is not a problem and solely amosite will most likely be used. This was true for the batch employed in the tubular molding operation, which was recently discontinued. It is of interest in this connection, that J-H uses only amosite in its process. Since a very dilute slurry, 20 to 25 water/solids ratio is employed, harshness- is not a problem. Nor does this slurry remain quiescent. Further more, the molding is a press and filter operation, vhich requires that the slurry possess a high degree of freeness. Thus J-H is able to take full advantage of the characteristics of amosite in both the slurry and the product. 01 0G2 03C5 16 The latest survey of competitive hydrous calcic silicates revealed that all but J-M Thermobestcs contained a blend cf tvo types of asbestos# Only chrysotile is used for #<aylo-10 and Saylo-20 core materials. This is done to obtain the optimum pouring characteristics with these slurries of lover water content# Earlier it was stated that only chrysotile and arosite types of asbestos have been found to be satisfactory, or to be econrtncally feasible# Crocidclite asbestos gives highly satisfactory performance, but prices have been too high to permit its use# Like arosite, it cones frcn Africa# In fact, deposits are frequently closely associated# It is commonly called "blue asbestos", and has the complex formula, X^O#jEeO.Fe2O3.8SiQ2.H2O. Vollastonite Comments on vollastonite are inserted here because it is a fibrous material and is used for reinforcing of the hydrous calcims silicate in Eaylo products. Vollastonite is anhydrous nono-calciun silicate, CaO.SiO?. It nay be made synthetically, but we are concerned here with the natural mineral. It is supplied in several degrees of fineness from a source in Kev Tork State by Godfrey L. Cabot, Inc. It will be recalled from discussions of formulations in Chapter III that grade C-101 was used in Eaylo-10 thermal insulation, and grade P-1 in Eaylo-20 thermal insolation and in Kaylo-20 core. The C-101 grade is a relatively coarse material having needle-like crystals up to 1/UB in length. It is used to replace a part of the asbestos in an amount of 100 lbs. for 100 lbs# per batch. It functions solely as reinforcing and does not contribute to suspension. Therefore, the amount that can be substituted for asbestos is limited. It has all of the prop erties of a good reinforcing material, being strong, having good adhesion to the binder, and being unaffected by heat up to temperatures far beyond the limit that either type of asbestos can withstand. But perhaps the. greatest advantage is to be found in its low cost, about $26 per ton delivered, compared with about eight times this amount for the asbestos it replaces. At a replacement of 100 lbs# for 100 lbs*, a savings of about $10 per batch is realized. On a typical day, a total of 28 to 30 batches of Kaylo-10 light density slurry may be poured. Wollastoaite C-101 first went into the batch the latter part of August, 1958. Both Kaylo-10 and Kaylo-20 core formulations at present employ hydrated lime instead of quicklime in order to keep the consistency of the slurry low enough to permit it to be cast satisfactorily. The writer feels there is a strong possibility that if quicklime were substituted for hydrate, and vollastonite C-101 for a part of the asbestos, a satisfactory slurry and as good, if not better, prQdunt would result. Studies are indicated on this subject. ' 01 062 030-3 17 Wide use of vollasucuite can be expected if and when the manufacture of specialty items becomes of consequence. This especially applies to relatively high density xcr.ctlite, or Kaylo-20, bodies. Experimental pieces of a body composed of 502 xcnotlite-502 vollastonite C-101 at a density of 50 pcf hare shovn a modulus of rupture of 390 psi. After heating at 1600F for 2k hours, the modulus of rupture vas 220 psi and the material had undergone a shrinkage of only 0.62. Vollastonite P-1 is an extremely fine, cr pigment, grade. It is used in both Kaylo-20 thermal insulation and core batches. Being cf pigment grade, it is, naturally, higner priced than C-101, but still is much cheaper than asbestos. Whether or not it is preferable to C-101 in Kaylo-20 batches is still a moot question, and should be resolved sometime. Plant personnel are reluctant to change because of satisfactory experience vith the finer material. It should be mentioned here that no thickening of Kaylo-20 slurries occurs at any stage prior to autoclaving, so that these slurries remain in a fluid state for longer periods than do those of Kaylo-10 formulations. Bleeding, or loss of water, from the cast vare can be of major concern. Thj* could be a determining factor in a choice between the finer and the coarser grades of vollastonite. Lime Lime, of course, supplies the CaO to combine vith the SiOj of the batch to form the hydrous calcium silicate binder. It must be a high calciua Use. Highly impure limes, or dolcmitic limes, containing appreciable amounts of magnesia are unsatisfactory. The magnesium silicates which result from the reaction of XgO vith Si02 do not function as a cementitious material. But even worse, the delayed hydration of MgO to Hg(0H)2 involves expansion and ' results in a disruptive force after the Kaylo mass has set up. Fortunately, the composition of the product is closely controlled by reputable producers, and reasonably constant quality can be expected frcm any one source. Quicklime Quicklime is employed in both Kaylo-10 and Kaylo-20 thermal insulation ' formulations. By means of controlled conditions of hydration during the batch miring operation, a "fat" line putty results which contributes largely to the desired non-bleeding characteristics of the slurry.' For this and other reasons, a very reactive line is needed. To meet these needs, a "soft" burned line, yet free frca excessive amounts of uncalcined limestone, is required. Mai^ producers cater to the steel manufacturers who prefer a "hard" burned line. Such lines are not generally suitable. It has been the experience at Berlin that no readily available line vas quite as satis factory as that produced by Warner Company from its Bellefonte, Pennsylvania plant. 01 0G2 03oy 18 Hydrated Line Current-/, hydrated line is used in the heavier density Kavlo-10 and Kaylo-20 core f emulations If quicklime were to be employed in the present femulations, the consistencies of the slurries would prove too high for satisfactory handling in the casting operation. Ccmercial hydrate has certain disadvantages. The delivered price is higher for a given CaO content, and it is mere susceptible to deterioration during storage. Snail inventories and frequent analyses nust be the practice. It is hoped that further studies of core formulations will result in nodifications which will permit the use of quickline. Silica Two forms- of silica are used in the Kaylo-10 thermal insulation and core fomulations. They are the crystalline tripoli and the anorpheus diatcnaceous earth. Kaylo-20 formulation contain only tripoli at the present tine, but United amounts of diatcnaceous earth, up to about 202 of the siliceous fraction, have been used in the past. The amount of diatcnaceous earth that can be employed in Kaylo-20 formulations is United by its re active alunina content. Actually, it was found in laboratory tests with a diatcnaceous earth particularly low in AI2O3 that high quality Kaylo-20 products were foraed nore readily when the silica fraction consisted of 60$ crystalline silica-h02 diatemapeous earth than when composed of entirely crystalline silica. But larger shipr.ents of this particular brand of diatoaaceous earth proved to have higher alunina contents and to be quite variable in this respect. Consequently, advantage could not be taken of the characteristics shown by the laboratory sample. Amorphous silica in the fora of silica gel is suitable for both Kaylo-10 and Kaylo-20 formulations, but the cost is much too high for use as a raw material in production. Triooli . The term tripoli has different connotations in various countries and in the literature. In American usage, tripoli is a microcrystalline quarts. There are two extensive deposits located in southern Hlinois and in Arkansas. Both are being exploited. The material being used at Berlin cones from the former, and is supplied by Illinois Minerals Company. # While it is in reality a quartz, the microcrystalline structure renders it much more reactivs than ordinary quartz of the same screen fineness. The delivered price at Berlin is $28.06 per ton for 95% minus 325 mesh, compared to $15.60 for quartz ground to the same fineness. Th^-g represents a difference of $2.18 per batch of Kaylo-10 thermal insulation, but experience has shown that the reductions in cylinder time made possible by its use more than compensate for the added cost of the tripoli. For the autoclaving periods accepted as standard in plant operations, greatly inferior ware results when quartz replaces tripoli. Or stated differently, longer autoclaving is required to obtain ware of the same quality when quartz is employed. 01 082 0305 19 Attempts hare been made to Increase the reactivity of ordinary quarts by grinding to extreme fineness, but the reactivity did r.ct approach that of tripoli of a 95% minus 325 nesn fineness. This experience incicates that the processing of plate glass grinding wastes to provide a source of silica does net hold great premise* In the formulation for Kaylo-10 thermal insulation, the tripcli con stitutes 302 of the total silica* In the Kaylo-10 core batch, the tripoli accounts for aocut 79% of the siliceous fraction. Celatom (Diatcmaceous earth) . Celatca is the trade name of the diatcmaceous earth produced frem Nevada deposits by Eagle-Picher Company. This render selects material from only certain strata and blends it for our use. Prior to shimnent, each lot is tested by their quality control laboratory for organic matter content, using the method and standards prescribed by us, to assure that the organic content is safely below injurious levels (about 200 pen). This tested and approved product is labeled Celatom N-370. The results of these determinations of organic content reach the plant by air mail before the Celatca arrives. Diatcmaceous earth, or diatenite, is the fossilised remains of diatoms. Diatoms are microscopic single-celled aquatic plants which have the ability to extract silica from the water in which they live, and with this silica build for themselves external skeletons. Vhea the diatom dies, this skeleton settles to the bottom and remains after the organic part of the plant has disappeared. Over ten thousand different types of diatoms have been iden tified. Naturally, there are great variations in size, shape, surface area, bull density, etc., among the diatenites. Furthermore, although all are composed for the most part of amorphous silica, they differ greatly in the amounts of impurities or other oxides that they contain. All of these different attributes have a bearing on the suitability of a particular diatemite deposit for use as a raw material in Eaylo formulations. # Diatcmaceous earths other than Celatcm N-370 have been given thorough trials. They have generally proved less satisfactory because of lesser reactivity, or Decause of variable composition frem shipment to shipment. In one instance, a vendor's supply of satisfactory diatemite became exhausted. While knowledge of the presence of gross amounts of impurities may eliminate a diatomite from further consideration, in many cases it is necessary to employ it in trial runs in order to evaluate it. Apparently many factors contribute to its measure of value as a Kaylo raw material. Certain diatomites, although pure enough and. having high surface areas, do not react with lime as readily as others. Celite from J-H falls in this category. 01 0g2 03Cb Diatomaceous earth is used in the batch fer two reasons. First, as an amorphous form of silica, it reacts very readily with lime. This property permits the cast ware to set up .or preharden in a relatively short time at temperatures in the neighborhood' of 200F. The preliminary setting or pre hardening of the cast ware greatly facilitates the handling of the filled molds in subsequent operation, and also makes fer easier stripping of certain sizes of ware after autoclaving. Also of importance is that scheduling of the cylinders is far less critical, because prehardened or set ware can stand for several hours on the floor if necessary before being autoclaved. 20 lie second reason for using diatcmite in the batch is its contribution to the thickening of the slurry* giving it gre-ter water-retaining and non-settling characteristics. It is true that nc diatcmaceous earth is employed in Kaylo-20 formulations, but Kaylo-20 products cannot be made at as low apparent densities. The minimum density of Kaylo-20 ware that is now practicable in production is about 12.5 pcf. that is to say, the absence of diatcmaceous earth in the formulation makes necessary che use of slurries of lower water/solid ratios. Since the vater/solids ratio of the Kaylo-10 core slurry is less than that for Kaylo-10 thermal insulation slurry, less diatcnaceous earth is required to give the same rate of prehardening and the same water-retaining properties. Clay It was mentioned earlier that it was advantageous to have a limited amount of reactive ai r-Hna present to enter the structure of the hydrous calcium silicate which constitutes the body of Kaylo-10 ware. A fine grained china clay (kaolinite type) is a most satisfactory and constant source of reactive alumina, and the silica of the clay is also reactive. This type of clay is used in an amount of 3.28J of the solids in the Kaylo-10 insu lation batch, and 1*37/5 in the Kaylo-10 core formulation. These amounts appear to be about the optimize in each case frcn the laboratory studies and the plant trials that have been made. Strengths are greatly improved, and low shrinkages at elevated temperatures result in the product. The presence of somewhat higher quantities of al^i-a _ results in ware shewing excessive shrinkage at high temperatures. Thus, it is essential that the a.iir-rin& content of the formulation be closely controlled. Large variations in alumina content of the diatcaacecus earth fraction render this control most difficult. Clays other than a kaolin or china clay might be used, but the use of a high grade china clay insures that objectionable impurities such as organic matter, sulfates, chlorides, etc., are not a problem. There is evidence that bentonite clays increase processing shrinkage. Alumina in the form of bauxite is not reactive in the K^ylo process. Inert Ingredients Studies have shown that the inclusion of extremely fine inert ingre dients in the batch reduces the thermal conductivity of the product remarkably. Through the addition of 115 of fine inert materials to the batch, combined with a change to a blend of amosite and chrysotile instead of chrysotile alone, the Rk" factor at 5$0? mean of the plant product has been reduced about O.lli from what it was in 1955* It is believed that this effect is mainly due to the increase in nisber of interfaces between dis similar materials encountered as heat flows through the insulation. The studies hare shown that combination of additives is better than & single inert substance. r 01 062 0201 A great msber and variety of materials have been found to be effective, and the choice for use in production is dependent, upon a nurser of factors. Requisites for a satisfactory additive of this nature are: i- should be inert and not interfere with the formation of the desired hydrous calcium silicate; the finer the grain size the better; infra-red blocking properties give an added advantage; it should not inpart undesirable color or shade to the product; it should be readily available and cheap. Caroon black is by far the most effective additive found to date for lowering ''k'1 factor, but its high cost and the darkening it gives to the product rule it out, for the present at least. On the other hand, iinestone ground to pass 200 mesh is not as effective, requiring 1C$ addition to produce the same amount of lowering of nkrt factor as 2% of carbon black, but it is by far the cheapest of all of the batch ingredients and does net cause a color change in the product. The considerably cheaper ground magnetite, Fe^O^, has been found to be almost as effective as ground chromite, Fe(Cr02)2, but the latter does not darken the product as much. As to be expected, there is seme reduction in strength cf the procact as the amount of fine inert material in the batch increases. Thus in lowering the thermal conductivity by this means, seme strength is sacrificed. Conse quently, a compromise must be reached in this natter. The present formu lation calls for 7*87$ of limestone and 3*28 of chromite for a total of 11.15$ of additive. It is likely that 11$ of limestone and b of chromite could be carried without reducing the strength to a danger Foint or where it would be objectionable to the customer. A reduction of .03 in k8 factor at 5500? mean could be expected. However, the plant experienced a period ' of low strengths in 1557 while employing 15$ of additive, and may accordingly object to the return to this much. But the formulation has been changed in several other important respects since then which have all contributed to higher strengths, and reoccurrence of the low strengths of 1557 is not to be expected. A return to 15$ of additives will not be proposed, however, until it has been first established that a product of more than ample strength can be made consistently with the return of waste slurry and of scrap Eaylo material to the batch. These two modifications to the batch are proposed for the immediate future. ' Perhaps research will in the future reveal an additive more effective than any now known, and it will not be necessary to employ quantities to the extent the strength is seriously affected in order to obtain nk" factors that compare favorably with those of competitive materials. Ground Limestone As mentioned above, ground limestone is one of the inert additives now in the Kaylo-10 thermal insulation formulation. It is supposedly a by-product in the lime industry, being too fine for most purposes. Nominally it is 90 minus 200 mesh, but most of the grains are as fine as face powder. 01 0G2 03OS 22 Although it is added to the batch to decrease the themal c0r.dtcttTt.t7 of the product, a cheaper batch results as a bonus* The delivered rrtce of the bagged material at Berlin is only $11 per ten* The average of the prices for the other ten solids of the femulation is 3h.7?8 per evu*, vhile that for linestone is only $0*550. The present material is a high calcim limestone, but a doicuitie limestone would serve as well* The fineness is the inpertant factor in this case* Chromite Iron chromite is the second additive being used to lower the "k" factor of the Berlin product* It has the added advantage of being effective in blocking infra-red radiation* This particular material is known as air- float chromite, and is available cocsercially, being a batch ingredient in certain glass container plants* The delivered price of bagged material is $2,653 per cvt., which is still cheaper than the average for the other ingredients* . Tamol #731 Surface Active Aeents Certain surface active, or dispersing, agents are effective in increasing the fluidity or flowability of a slurry. Tanol #731> vhich is supplied by Hois and Baas, is of this class* The addition to the Kaylo-10 insulation batch was begun on November 10, 1958* It 1s employed in an amount of 0.10? of the weight of the solids. This addition has proved most valuable in ' imparting excellent pouring characteristics to a slurry that was otherwise too thick and stiff to cast properly* The incidence of air holes and folds has been greatly reduced in molded pipe covering. 'While it does add $2*3h to the batch cost, the saving resulting from a lower amount of off-ware more than compensates for this increase* Tamol #731 Is a new development, and Berlin was one of the first cus tomers* Promise has been made of likely price reductions in the future* A satisfactory dispersing agent fer Kaylo slurries has been the subject fi research for several years. Many have been tried in the past, but their use was soon abandoned for one of two reasons: either they were foam formers with a resulting unfavorable effect on the "kK factor of the ware, or they caused unsightly staining of the product. Tamol #731 has neither of these disaevantages. Red Iron Oxide Coloring A small amount (about 0*3/0 of fine red iron oaide is added to both types of Kaylo-20 batches to give a pink color to the product* This is done to distinguish the ware on sight from corresponding Kaylo-10 material. 01 0G2 030=1 \ sf Chapter V RAW MATERIAL SPECIFICATIONS 23 The specifications as given here are not to be considered as being in final or standard fora* They are actually compilations of the properties and requisites cf the various raw materials, made to serve as the bases for the drafting of formal specifications. It should be emphasized that passing a specification based on con formance to a limited number of chemical and physical properties is no assurance that one material will function as veil as another is Kaylo formulations* Certain variables can exist that are not easily detected except by observations of behavior of the materials in trial runs of batches containing the material in question. The specification for each ingredient should contain a clause stating that it shall prove to be,satisfactory for use in the production of Kaylo products. Final grounds for acceptance or rejection of a particular material should be whether or not it compares favorably with standard performance in respect to speed of processing and to the quality of the product. No new source of any of the batch ingredients should be gives final approval before runs of laboratory and plant trial batches have been made and favorable results are obtained. Once a material has been approved, it is one of the functions of the Process Control Engineering Section to conduct the necessary tests in its laboratory at the plant to insure that no significant variation free speci fications occurs. It is also the responsibility of this group to advise as to corrective measures to be taken when the character of material on hand has changed due to conditions of storage or other reasons. Chrysotile Asbestos . Chrysotile shall conform to the following requirements and in addition prove suitable in plant trials for the production of Kaylo products. Two gTades of chrysotile are required for the production of Kaylo products, a shingle fiber and the shorter, stucco or plaster fiber. The former shall prove to be the equivalent of Grade hK or better in the Quebec Standard Testj the latter the equivalent of Grade 6D or better. The vendor shall guarantee that each material is of the chrysotile variety of asbestos. Optical properties rather than chemical analysis are to be the basis for judgment in case of dispute on this point. Maximum immunities: Cl S03 *20 .75* The chrysotile shall be supplied in bags of uniform weight, with the grade of the material marked thereon. Compressed material in paper bags is preferred. Approved vendors: Johns-Manville 01 062 03\ Araosite Asbestos Anosite shall conform to the following requirements, and in addition prove suitable in plant trials for the production of Kaylo products* There is no unifora system employed in the grading of ar.osite asbestos Generally speaking the grades of interest consist predcrnnantly of fibers longer than 3/8 or 1/2", and about 20 or 252 longer than ln. The anosite shall contain no nore than 2.02 of non-fibrous naterial present as rock or dust. The chemical composition shall conform roughly to the following: 502 Si02, 62 Al20p 372 FeO, U2 KgO, 22 H20. Before a new and untried material is purchased, representative samples must be furnished for comparison with "standard" fibers as to brittleness, tensile strength, fiber length distribution, etc. The aaosite shall be supplied in burlap bags of uniform weight, with the grace and manufacturers name marked thereon. Approved vendors: North American Asbestos Corporation. ' Pulverised Quicklime This line shall conform to the following requirements, and in addition prove suitable in plant trials for the production of Eaylo products. Substantially all of the pulverised line shall pass the No. 20 sieve and after slaking, not more than 1.02 by weight shall be retained on this size screen. Requirements as to chemical composition on an air dry basis are ls follows: When tested at Plant Place of i CaO Total Min. 2 CaO Available# Min. 2 B2O3 Max. 2 KgO Max. 2 SOj . Max* 2 9h.5 92.S 2.0 3.0 0.3 A.S.T.K. Designation C25-U7 (sugar method) 96.0 93.5 2*0 3.0 0.3 The line shall be shipped in paper bags strong enough to withstand normal handling without bursting. Weight of lime in each bag shall not deviate more than one pound, plus or minus, from the average weight. The bags shall be marked, ^Pulverized Lime", and shall also comply with the A.S.T.M. requirements for marking. Approved vendors: Warner Lime Company 01 062 031) f' v ' \ f / 25 Hydrated Lise This line shall conform -to the following requirements, ar.d la ad.di.ticn prove suitable in plant trials for the production of Kayio products. Wot more than 1.0% by weight shall be retained on the Wo. 30 sieve, nor acre than 15*0% on the No* 200 sieve* Requirements as to chemical exposition on an air dry basis are as follows: When tested at Plant Place of Mfe. CaO Total Min* % CaO Available* Min. % R^O, MgC* SO3 Max* Max* *%/* Max* t/f 72.0 69.5 1.5 2.0 0.25 *A.S.T.M* Designation C25-L7 (sugar sethod) 73.0 70.0 1.5 2*0 0.25 This line shall be shipped in paper bags strong enough to withstand nomal handling without bursting. Weight of line in each bag shall not deviate more than one pound, plus or minus, frea the average weight* The bags shall be narked, "Hydrated Line", and shall also comply with the A.S.T.M. requirements for marking* * .. Approved vendors: Warner Lime Company Tripoli This material shall conform to the foilwing requirements, and in addition prove suitable in plant trials for the production of Kayio products. Evidence must be presented that this silica flour is produced from a . fora of microcrystalline quartz commonly known in the tJ.S*A* as "tripoli". Not more than 1$ shall be retained on the No* 100 sieve, nor more than 5% on the No* 325 sieve* At least 50% by weight shall be finer than 25 microns* Requirements as to chemical composition on nas received" basis are: Si02 Min. % 98.0 R2O3 Max* % 1*5 Loss on ignition Max* % 1.0 This silica flour shall be shipped in paper bags strong enough to with stand normal handling without bursting. Weight of contents in each bag shall not deviate more than one pound, plus or minus, from the average weight* Approved vendors: Illinois Minerals Company 01 082 03l . . r v * 26 Diatonaeeous larth This material shall conform to the following requirements, and in addition prove suitable in plant trials for the production of Kaylo products. Not mere than- 0.15 shall be retained on the No* 20 sieve, nor mere than 8.C5 on the No. 325 sieve. Requirements as to chemical composition on "as received" basis are: S102 . A1203 Fe203 Total R2O3 Loss on ignition Organics Min. */* Max. Max. Max. %a/& Max. % Max. 80.0 7.0 ii.0 10.0 9.0 200 ppsr* As tested by OCF method, June 5> 1956 Revision, and employing color standards to be provided by OCF* This diatenita shall be shipped in paper bags strong enough to vitistar.d normal handling vithout bursting. Weight cf contents in each bag shall not deviate more than one pound, plus or minus, from the average weight. Approved grades and vendors: Celatoo N-370, Eagle-Picher Company sis 'This material shall conform to the'following requirements and in addition prove suitable in plant trials Xcr the production of Kaylo products. The clay shall be the china or kaolinite type, and uncaicined. It shall be pulverized clay showing no more than 1.05 on a No. 325 sieve. Requirements as to chemical composition on "as received" basis are: SiOo Range % U0 to 50 AI2&3 ft40** 2 35 to US S^+AljO^ Min. $ 8I1.O Loss on ignition Max. % 15*0 . The clay shall be shipped in paper bags strong enough to withstand normal handling vithout bursting. Weight of contents in each bag shall not deviate more than one pound, plus or minus, from the average weight. Approved vendors: Georgia Kaolin Company Kraft Chemical Company 01 062 0313 r 27 Limestone Flour This material shall conform to the follow, ng requirements, and shall in addition prove to be suitable in plant trials for the production of Kaylo products* Ertree fineness is a major requisite* At a given price, preference shall be given to limestone flour having the scaliest particle site* In any case, there shall be no more than 5% retained on No* 325 sieve; 60.C2 or more of the limestone shall be finer than 10 microns* Both high calcium limestone arei dolcnitic limestone are acceptable. Requirements as to chemical composition on "as received" basis are: CaCCH or CaCO^+MgCOo Moisture SIO2 ^2^3 Kin. Max* Max* Max* % % % % 97*0 1*0 1*0 1*0 This material shall be shipped in paper bags strong enough to withstand normal handling without bursting. Weight of contents in each bag shall not deviate more than one pound, plus or minus, from the average weight* Approved vendors: Warner Lime Company Iron Chromiha This material shall conform to the following requirements, and shall in addition prove to be suitable in plant trials for the production of " Kaylo products* Extreme fineness is a major requisite. No more than $% shall be retained on the No* 325 sieve* A suitable material 1s that known as "Air Float Chromite", and is of a purity comparable to that of the chrcmite employed as a colorant in the glass container industry. . This material shall be shipped in paper bags strong enough to withstand normal handling without bursting. Weiit of contents in each bag shall not deviate more than one pound, plus or minus, from the average weight. Approved vendors: Frank Samuels and Company Wollastonito This material shall conform to the following requirements, and shall in addition prove to be suitable in plant trials for the production of Kaylo products* The vollastonite shall be the natural mineral graded to give a definite particle siz.e range* Two grades are of interest* They correspond to Grade C-101 and Grade P-1 as produced-and labeled by Godfrey L. Cabot, Inc* 01 062 0314 28 Tills mineral shall he shipped in paper bags strong enough to withstand normal handling without bursting. Weight of contents in each bag shall net deviate more than one pound, plus or minus, from the average weight. Approved vendors: Godfrey L. Cabot, Inc* Red Iron CTide This material shall be the pigment grade of red iren cnide. . Approved vendors: C. E. Williams Company Dispersing Agents A dispersing agent to be acceptable must be capable of greatly increasing the fluidity of Kaylo slurries when amounts no greater than 0.102 are added, must not cause the formation of foam during the misdng of the slurries, and must not result in the staining of the product. The standard of performance is that of Tanol #731* Approved vendors: Eohn and Raas Company f 01 062 0315 < Charter VI V. * ' BATCKEJG AtfD MHUiu OFEBATIOUS 29 The detailed procedures to be followed in this step cf the process, and in subsequent operations, are given in a manual prepared by C. ?. Silkvood, and approved by 0* W. Pfeifer, titled "Kaylo Manufacturing; Process and Operational Control". This manual was issued June 11, 195S* It is the intention here to refer only to the high lights of the abovementioned manual, and to offer some further explanation where such is con sidered helpful* Formulation changes may be made only upon authorisation of the Plant Manager. It is the responsibility of the Chief Process Engineer to calculate the actual quantities of each of the raw materials and the amount of water required, to specify the temperature of the water, and to give detailed instructions to be followed in the treatment and mixing of the ingredients of the batch. All of this is recorded and published on a standard form. Bagged, rather than bulk, raw materials are employed in the batching operation. Formerly, the SayreviHe plant operated with a weighing and accinaulating system for its raw material handling and batching, but experi ences there indicated that the handling of bagged ingredients was to be preferred, both frcm the standpoint cf over-all cost and control. The specified weights of the principal raw materials for the batch are determined by using an equivalent number of bags. Where possible, the weight of a particular ingredient is chosen so as to represent sene whole number of bags. In cases where this is not feasible, seme easily defined fraction of a bag is chosen. It is necessary, of course, with this scheie to make a regular check on the average bag weight of the raw materials as they are received. * If a significant variation is evident, the material is isolated, and means are devised for using it. In such cases the vendor is advised and asked to correct the condition. . The batching and mixing operations begin with the measuring out of the predetermined amount of water at a prescribed temperature into one of the two tanks that are used to disperse the asbestos in water. These are cylin drical tanks with impellers located near the bottom. In the pimping frcm one tank to the other, the suspension passes through a Bauer mill, the plates of which may be set at a desired clearance. The batching and mixing to be described is that for aylo-10 thermal insulation batch because the operation is the most complex. More ingredients are employed and the recovery of waste slurry is involved. . r' \ . 01 062 03KJ 30 The amount of water used for the batch is determined by the siocnt of dry solids plus the amount of solids contained in the volxme of waste slurry added. The volume of waste slurry to be used per batch is determined by the quantity that has been collected in the two salvage tanks (similar but somewhat smaller than the asbestos tasks), and the number of batches of Kaylo-10 light density scheduled to be run for the day. The waste slurry is, of course, much mere dilute than the batch slurry, since it consists of the batch remaining in the lines and mixers plus the water used to wash out the equipment. After the prescribed amount of clear water for the batch has been metered into the No* 1 asbestos tank, and the Tamol #731 added, a measured amount is ptsiped to the No. 2 asbestos tank, and thence to the hydrapulper for the hydration of the quicklime. This quantity is about four times the weight of the quicklime. To the vater remaining in the No. 1 tank, a metered amount of the dilute waste slurry is added* To this tank is then added, all of the asbestos, the clay, and a half a bag or so of the quicklime going into the batch. (Asbestos disperses better in lime water-than in straight vater.) These solids are put into suspension by the action of the impeller at the bottom of the tank and pumped into No. 2 asbestos tank through the Bauer ^-LVL running at a clearance of 0.020n. The treatment given the asbestos in the Bauer mill, which is a fiierising operation, is varied according to the blend of asbestos being used at the time and to the characteristics of the final slurry. If a higher consistency is desired, or if clogging of the pouring nosmles is being experienced, the plates of the Bauer mill may be set closer together, or several passes may be made through the mill, or both. Also, if the slurry is shoving abnormal tendency to bleed, more work may be done on the asbestos by the Bauer mill. While the asbestos suspension is going through the Bauer mill, the operator dumps the remainder of the quicklime and the woHastonite into the hydrapulper containing the water for the hydration of the lime. The hydrapulper is then set to run for about three minutes to thoroughly the lime and vater, and to get the hydration of the lime veil under way. After the asbestos suspension has gone through the Bauer mill into asbestos tank #2, it is pumped from there to the hydrapulper on top of the lime putty. When this is complete, the hydrapulper is put in motion and the diatcmaceous earth, tripoll, and additives added. The complete batch is allowed to mix for about eight minutes. The hydrapulper is a piece of equipment primarily designed for the production of pulp slurries in the paper industry. The violent action imparted to a fluid results in very thorough mixing within a short time. Its action also is effective in further opening of the asbestos fibers. Because of this, the bydrapulping period must be controlled. The consistency of Kaylo slurries increases with, increases in time of mixing in this equipment.' 01 062 0311 \ ( *51 For all of its effectiveness as a mixer, there say be a disadvantage in the use of a hydrapulper. There is a possibility that an undesirable amount of air is entrapped in the slurry by the violent action. If this is true, and if these air bubbles are for the most part carried through the process to the finished product, the ,:k" factor of the ware is likely to be affected adversely. This should be a subject fcr study. Following rriying in the hydrapulper, the slurry is pumped to a holding mixer, which is a Robinson ribbon mixer. At this point, samples of the slurry are takes for determinations of consistency, density, and temperature. The consistency figure is the value obtained with equipment specially designed to measure the resistance that a revolving brass cone meets as it penetrates the mass of slurry. Consistency must be held within certain defined limits because of its effect during the filling of the molds. A high consistency causes the slurry to flow sluggishly is the molds, resulting in air holes, slip planes, and pouring folds or tears. Low consistency will result in bleeding after casting, water veins with subsequent cracks or separations, and shifting within the nolds during handling. The density of the slurry is reported as weight per cubic foot. It is determined simply by weighing a knows volume. Control of slurry density is essential in the control of the density of the product. Determination of slurry density also affords a check on batching as to the solid raw material weights and quantity of water employed. All of the pertinent data are obtained, and recorded at this point. Departures from normal are promptly reported to the Production Superintendent and the Chief Process Engineer. The latter attempts to determine the reason for the departure, and must decide if the proper correction can be made, or if the slurry must be dumped. After it has been determined that the slurry is normal, it is held in the holding miner on the batch floor, with just sufficient aiadng action to maintain uniformity, until demands on the pouring lines call for it to be pumped to any one of the pouring mixers. There is one such mixer in the No. 2 pouring line (molded pipe covering casting), and there are two'in the No* 1 pouring line (flat ware). These mixers are similar in type to the holding mixer on the batch floor. The existence of only one holding mixer is a serious handicap to efficient operation, since it may be called upon to handle any one of four types of slurries. Scheduling, therefore, is extremely critical inasmuch as it mast be free of any remnants of previous batch of different type at the tine the new batch is ready to be pumped from the hydrapulper. The matter is further complicated in that its availability must be tied in with cylinder opening schedules. , Plant personnel have asked for assistance from General Engineering in planning for additional batch storage facilities. A holding mixer for Ksylo-20 slurries is especially needed, and would be of unestinable value in maki ng for more efficient operation. Kaylo-20 slurries can be held practically indefinitely before casting. If storage facilities are-available, mixing can be done when most convenient on the batch floor and independently of the cylinder schedules. 32 The entire batch siring facilities should be the object cf stury and comprehensive planning in view of the greatly increased demands fcr pro duction. Present batch nixing facilities are essentially the sane as those that first vent into operation on March 12, 19?ii. Mere than twice as much slurry per day is being mixed now than it was then. The ultimate capacity of the system under the most efficient operation was considered at that time to be about 32 batches per day of the same type cf slurry. Mot only has this "limit" been exceeded, but the plant has been called upon on certain days to mix three types of slurries instead of only one. The exact manner in which waste Kaylo procucts will be returned to the raw batch has not been determined as yet. Nor is it known how much of the material presently sent to the dtsp can be safely incorporated in the batch. The quantity of dust that results from the trimming, renting, and planing operations far exceeds the weight of the reject ware. This Kaylo dust is collected in dust arrestors, and usually amounts to more than 5 tons per day, or nearly 15? of the weight of the solids that go into the Eaylo-10 thermal insulation batches daily. Laboratory results thus far indicate that it is likely that this much can be returned to the raw batch without serious degradation cf the quality of the product. In utilization on a plant scale, this dust will probably be transferred from the collectors to a tank where it will be mixed with water at a definite vater/solids ratio. Plans call for two such tanks. During any one day, the dust and water will be mixed in one tank, and the dust-water slurry prepared the previous day drawn off frem the other as needed in the batching operation. " \ 01 062 03 R V / 33 Chaster VTI FORKING Casting Method With a foiling method dependent area the casting of a fluid slurry to shape, such as used for by far the most of the production at Berlin, a great many of the defects in the finished product originate at the pouring or casting station* The person who perfcrr.s the task of filling the adds is a key figure in determining the quality of the ware* A considerable amount of art is involved at this stage of the process. Accordingly, the plant has generally followed the practice of requiring that a man "work upn to the Job of pourer* Also, training manuals, emphasising the intricacies of the operation and describing in detail the procedure to be followed, are available and are required reading. The Shift Foreman is directly responsible for the performance of his pourer and other nebers of his crev* la spite of all efforts to obtain uniform performance mong the crews, this objective is rarely attained fer ary one month* Quite typical is the record for Feoruary, 1959* Of the four crews, one was responsible for 362 of the off-ware, whereas another was charged for only 162* This high offware crew, which poured a fourth of the production, was charged with mere than one-half of the ware rejected for air holes, and had five tines as much ware lost for this cause than did the best of the crews in this respect* The answer to this problem secs to lie in eliminating as much of the human element as possible in this operation* Efforts are now being directed along these lines, as further discussion will reveal* There are two pouring lines: No* 1 where all of the flat ware is cast; No. 2 where only molded pipe covering is poured* Current demands for pipe covering are such that some must also be poured on the No. 1 line* . The pouring line actually begins at the station where the autoclaved ware is stripped from the molds* A sugary follows of the operations per formed on the No* 2 or molded pipe covering line* ' A tier of filled molds (full car flight) is taken from a train that has been pulled from the cylinder and delivered by means of a lift truck to the end of the line, *faere the ware is stripped from the molds by the stripping gang of the crew* Here the processed ware undergoes its first inspection* A piece of ware with gross defects is discarded at this point* A report of the ware discarded is made on the Pour and Strip Recap form which originated when that particular train was poured and which accompanied that train throughout the complete process, with all pertinent data at each step being recorded thereon* ... . *I As the ware is stripped, it is color coded to the proper pouring crew. 01 062 033d A aost significant control check is na.de by the weighing of a repre sentative sample to determine its moisture content. One piece of each sine ware in each car is weighed and the weight recorded on the Pour ~nd Recap fora. By comparing with the preprinted maximum weight for "dry41 ware of this size, it is determined whether or not the ware has to receive supplementary drying. These data are also employed in establishing the proper cylinder cycles. It is the practice for a member of the Quality Control staff to rake spot checks at the stripping station. Here the ware can be readily identified with a specific train, cylinder, and crew. Also of major importance is that faulty molds responsible for off-ware can be detected at this point and taken out for repair and/or cleaning. After the ware has been stripped from the ncld, the cavity and core are coated with a aold release. This is an raulsion of about 32 of polyethylene in a fairly heavy petroleum oil compounded at the plant. The oiling of the molds is performed by hand, the oiler rubbing a rag that has been dipped in the raulsion over the surface. All too often a poor job is done here. Incomplete coverage often results, as does deposition of excess oil in some parts of the mold. Mechanical application of the oil would, in all prob ability, provide a better job at a saving in manpower. This is one instance where the human element could be eliminated to an advantage. A project for the mechanical oiling of flat ware molds is now on the docket of General Engineering. This should prove to be a simpler arrangement than the one which would be required for the No. 2 line. Following successful installation and operation of the equipment for the flat ware molds, work will undoubtedly begin on a mechanical oiler for the pipe covering molds. Following the oiling, the strippers reass&ble the molds* that is, assure that the end spacers are in place, and reset the core into the cavity. This is done for all molds except those for E-sepnental pipe covering. For this relatively flat ware the core is inserted by the poorer and his helper after the cavity has been filled with the slurry. . The molds are moved along the line by a chain conveyor. On the No. 2 line the poorer alone has control of the stop and go. He exercises this control by means of a pedal at his station. As the molds move along the line they pass under a blast of compressed air before they reach the pourer. The purpose is to remove loose chips of old material that invariably fall into the cavity from sides and frames of the molds, etc. While the present arrangement accomplishes the purpose fairly veil, it is costly to operate. It is estimated that the cost of the compressed air runs about $800 per month. There appears to be an opportunity here for more efficient equipment with lower operating costs. When the molds arrive at the pouring station, the pourer adjusts the rate of flow for the slurry to a speed he considers proper for the size of the mold to be filled. The slurry is pumped from the pouring mixer through a hose with a pouring nozzle attached at its end. The pourer controls the 01 062 0351 r \ ( 35 rate of flov by adjustment of an cutlet valve and by regulation cf a variable speed pump* For vare of lesser thickness he employs a pouring nozzle S" long and having a nominal slot opening of 3/8". For the thicker vare, he uses an QB long nozzle vith 5/8" vide opening. The pourer has instructions to follow a certain prescribed pattern cf operation during the filling. But there are, nevertheless, certain vari ations in node of operation characteristics of the indivicuai. This is, perhaps, typical of any* field of activity where particular skills, coordi nation, and pride in the vcrk being performed are concerned. Efforts are in progress toward the development cf a full length (approx. 31i) pouring nozzle for pipe covering. There is reason to believe that a nozzle of this nature voula. eliminate much of the human..element from the pouring operation. Furthermore, it should reduce the incidence cf air holes, slip planes, and folds which occur to seme extent vhen the much shorter nozzle is employed by even the best pourer. For flat vare on the No. 1 line, the pouring nozzle is essentially an elbow on the end of a 3a diameter hose, having a rectangular shape at the eait of about 70% of the area of that of the hose opening. Development cf a 5hB long pouring nozzle is the aim in this case. A gang cf three melds could be poured at the same time with a nozzle of this length. Better aligznent of the asbestos fibers in the vare should also result. As night be surmised, the first problem to be solved in the development of these much longer nozzles is that cf obtaining and maintaining uniform flov over the entire length. The presence of asbestos fibers in the slurry makes the problem more difficult than if a perfectly homogeneous fluid were being dealt vith. The second stage of development will be concerned with ease of handling on the line. Following the filling of the pipe covering molds, the overflow is screeded off by the pourer1 s helper vhen he is available for the task or by the' pourer himself when the helper is engaged with the hoist in lifting a gang of the molds off the line onto the car being loaded for entrance into the prehardener, the next step of the process. The excess slurry that is screeded from the pipe covering molds on No. 2 line goes into a sump and is ptmped into the pouring mixer for the No. 1 line. There are always seme chips of hardened Kaylo material on the sides of the molds and frames which becccte loosened during the handling on the No. 2 line and then fall into the slurry in the siszp. Formerly only flat vare vas cast on the No. 1 line, and the effect of the presence of chips in the slurry on the flat ware vas negligible. But when the practice vas begun of casting pipe covering also on this line, the clogging of the nozzles with the narrow openings affected both production and the quality of the vare. It is necessary, therefore, to pass the sump slurry through an attrition mill, such as a Bauer mill, before re-use. The plant is planning an arrange ment whereby the sump slurry of both lines is emptied into a and then passed through a Bauer mill to the pouring mixer on either pouring line, depending on the slurry requirements at the time. 01 062 03&SL 36 ' . V . After the car is loaded vith the filled r.clds, it is the resccnsibility of the pcurer's helper to sere the car into the pr^hardener. Ir. the case of the first and last cars of the train in schedule, this person records the tir.e of entry on the Four and Strip Recap fern. He also positions an apty car after a filled one goes into the prehardener. As perhaps vith any r.ethcd of forming, there are advantages and dis advantages inherent in the r.ethcd Just discussed. Among the advantages are: The actual casting is rapid; the rolls are simple and easily interchanged to meet demands of production; forming equipment is simple and compact; considerable latitude in batch formulation is possible. The major disadvantages are: The randen orientation of the asbestos fibers that occurs is not as favorable as fibers oriented generally in the planes of the major axes, in respect to nkK factor and to strength contributed to the product; the surface is not as hard and resistant to abuse, and of as tmifcm appearance, as that obtained by certain other methods of ferming; a large nmrber of molds are required, and an individual mold must acccmpary the vare through processing. Until recently, the casting method of forming did not permit the pro duction of sectional pipe covering in sites greater than that fer 12" pipe* The use new of a dispersing agent in the batch, and other batch modifications that have been made, have resulted in changes in the pouring characteristics of the slurry such as to make possible the casting of sectional vare through 23" pi?e sites* The molds, vhich vUl be of the nested or piggyback type to avoid undue vaste of space, are not yet available for production* When these sites do go into production, it vill be possible to eliminate all ' tri-segnental vare free the standard line of products* A disadvantage that has been reduced in significance to a great extent by the use of a dispersing agent in the hatch and vhich should be even less a factor vhen full length pouring nottles are available, is the creation of air holes, folds, and slip planes in the vare. Air holes detract from appearance, and adversely affect the "kn factor* Folds also mar the appearance of vare. Slip planes are discontinuities in structure and as such cause the vare to be more prone to breakage* There is another defect in many sises of present production of molded pipe covering that is of concern to the plant and to Sales. Too frequently the ends are not square* When detected the vare is given an end trim by hand* While vare corrected by this means is acceptable to most customers, it is not to certain others such as the Navy for instance* The Navy has a specification calling for a length of 36 minus 0* Detection of this defect in each and every piece is most difficult, and occasionally same vare vith out-of-square ends reaches the customer and is cause for complaint* The casting method itself is not responsible for this problem* The specific cause can be one of several* Among these are: Premature and unequal drying of the vare, thin vare and small sizes in particular, vhile in the hot cylinder prior to the time that an atmosphere of saturated steam obtains, resulting in excessive and uneven shrinkage; excessive build-up on, or improper placement of, the spacers. A,, 01 062 0322 37 The length of the mold cavity for pipe covering is only iron 36-1/S" to 36-3/3-6". This does not allow much for in process shrinkage (of which there must be sene to pernit stripping), and for and tnn, if a 36" long finished piece with square ends is to be obtained. At the tine rscst of the molds were purchased, several persons, including the present Plant Manager at Berlin, argued for longer molds with end triming of all M.P.C., but the decision was made to use the shorter lengths. It is generally agreed now that this was the wrong decision. The sane cistake should not be na.ee again in the design of equipment for a new plant. Of the various types of inperfections that cause rejection cf pipe covering as off-ware, "broken corners" has almost always constituted the greatest percentage of the total. As would be expected, large sectional sizes of the lesser thicknesses are particularly susceptible to this damage during stripping and subsequent handling in the plant. The sizes 6" x 1" ana 12" x lu are examples. Had molds of greater lengths been available, much of the ware with damaged ends could have been saved by end tramming. In an effort to get out of the difficulty caused by out-of-square ends without going to the very great expense of replacing the present molds with longer ones, the plant is trying out three different thicknesses of stainless . steel spacers as replacements for the old and thicker black iron spacers. The lightest gauge that will stand up will be used. The additional length that will be gained is fren 1/8" to 3/8". General Engineering has the project for a conveyor to carry all molded pipe covering from the trim saws to the wrap and pack area. On this conveyor ail pipe covering will be end trisied. Perhaps some pieces will receive only a "kiss", but even this would help f some to correct the out-of-square ends condition. ^ ftoQtiy.g- of Ballets As the size of pipe covering decreases below that for 2" pipe, difficulties are experienced in forming it by the method discussed above. A major diffi culty lies in the tendency of the thin cores to deform during repeated runs. ' Accordingly, small sizes of pipe covering are now made at Berlin by cutting rectangular billets frea flat ware, trimming outer surfaces to give a hesi-cylindricai shape, and routing to the desired inside diameter. * This ware has a rough and unpleasing appearance, and is more susceptible to breakage than cast ware. For these reasons, there are serious objections to it on the part of some customers, and absolute refusal to buy by seme. From the standpoint of manufacture, the routing method is a costly and wasteful operation. Plans are to abandon this method of forming if and when the . method discussed below proves successful. - P.oucing of I.D. in Solid Haif-Ronad B^lets This method involves the casting of solid half-round billets and then form pipe covering by routing out the interior to the. .proper inside diameter. ^ Thus the exterior has a cast surface and presents the same appearance as the other molded pipe covering being produced. Obviously, much less material is wasted in routing to the interior dimensions only. 01 062 03SW 38 The plant has demonstrated vita trial molds that solid half-round billets can be procuced successfully. In principle, the mold is a rectangular pan with a scalloped insert. Such an arrangement can be filled in the sane manner as a flat vare nola. Studies are in progress at the plant cn improvements that vill make for easier stripping, handling of the vare, etc. But of major concern is the design and building of routing and trimming equipment for billets of this nature. General Engineering has this project on its docket. After having inspected a sample piece of vare that had had the I.D. routed by semi-mechanical means, Sales personnel have been pressing for the earliest possible production date. Vertical Castinz or Tubular Molding Tor the past few years, and until January 21, 1?59, certain small sines vere cast and prehardened in tubular form by means of original equipment developed for the purpose. The use of this equipment vas discontinued as the result of conclusions reached in a study of the economics involved. There are three reasons vhy an unfavorable economic picture vas obtained: 1. An abnormally high percentage of off-vare resulted for production over extended periods of time; 2. Maintenance costs vere high; 3. The equipment vas designed primarily for demonstration, and not for production; accordingly only a single bank of molds vas available for use. . Conditions 1 and 2 above resulted because super-atmospheric pressures vere involved. Elevated pressures vere employed to reduce cycle times and increase rate of production per mold cavity. But in so doing the problem of maintaining seals and preventing leakage, day in and day out, became a major one. A leak could be responsible for loss of slurry from the mold, and for boiling and blow-ups in the vare. Also because elevated pressures vere involved, control and proper balance of pressures and temperatures throughout the system vere critical. For example, if at any stage the temper ature of the vare vas such that the vapor pressure of the water within the vare exceeded the pressure being exerted externally on the ware, the ware would crack or blow up. When the equipment vas in good repair, and the proper cycling, temper ature, and pressures vere in effect, ware of excellent quality vas produced and the percentage of off-vare vas exceptionally lev. During the period it vas in production, its behavior was similar to that of the little girl of nursery fame, "When she vas good, she vas very good; but when she vas bad, she vas horrid." Previous experience with vertical casting at the plant should not rule out further consideration of the-^method with certain modifications. Perhaps the use of elevated pressures is*hot feasible for production equipment. It may be better to cast slurries at temperatures near the boiling point 01 062 0345 39 of vater into vertical molds, maintain this temperature in the cast piece by means of hot vater circulating around the mold and throng1** the cere, then eject the tubular piece after it has hardened sufficiently fer safe handling. Equipment would be much sinpler and easier to control than the former arrangement. Certain persons within the organisation have seme definite ideas on a process of this nature. Pabco Caltenp is made in sices by* a somewhat similar method, so the principle is not nev and untried. The advantages of any* vertical casting- prehardening-ejecticn method are: low mold inventory*; and the fact that the mold does not accompany the molded piece through the cycle; with resulting saving of autoclave space and of heat that would otherwise be used in heating the mold steel# Press and Filter Method A press and filter method is employed by Johns-Hanville for the pro duction of Thexmobestos. In this process a very dilute slurry (vater/solidsapprox. 18 to 20) is maxed at a temperature of about 165E and then sent to tanks where the slurry is heated by the injection cf live steam to about 200?, and maintained at this temperature until a desired gel structure is obtained (2 to 3 hours). By the addition of the condensate from the steam employed in heating the water/solids ratio of the gelled slurry at the end of the gelling period is about 2b or 25 to 1# This slurry is then ready for the molding operation. At each press station there is a tank to receive the amount of slurry required for the piece being molded. The exact volime of slurry being received is determined ba probe for level control. This amount of slurry is then pressed and filtered in an elaborate mold at a pressure of 75 psi ' to the desired si2e and shape. Through the loss of vater by the press and filter action, the vater/soiids ratio in the molded article is about 5 to 1. Since the solids are in a gel state, the molded ware possesses considerable cohesion and "green" strength. (Details of the J-H process is contained in the report, "Johns-Hanville Themobestos Plant Visitation", prepared by R. S* Grant, July 10, 1958.) The advantage of this process is that it produces a product having excellent properties: low nk" factor, high strength and resistance to abuse, dimensionally true, and pleasing appearance. Also, because of the high state of mechanization, little of the human element is involved. The disadvantages are: 1. Offers little flexibility as to formulation; workable formulation is costly. 2. Formation of a gel of required properties is critical. 3. Molding stations are expensive and space consmaing. - iu Customer servicing is of concern because of the amount of labor and time 'required to make a mold change. 01 062 035.6 hO Other Methods That Merit Further Stucrv A anther of other methods of ferring have been tried ir. the past to varying extents la the plant laboratory and at the research laboratories. Certain ones, such as centrifugal casting, ana continuous prehardening and forming, do not seen to merit further study for one reason or another. On the other hand, results vith others have been sufficiently promising to afford reasons for further study. Among these are: Filter press method (Denny); extrusion of prehardened and plastic bodies to shape (similar to the forming of clay pipe); pressing of prehardened light density flat vare to core material densities. Undoubtedly ideas as to other methods will occur as tine goes on. 01 062 LX Chapter phehasde:^:^ Following the casting step in the Berlin operation, the slurry it the moles is partially reacted, and harder.ee to a state that considerable pressure with the finger mist be exerted to make an impression. This is accomplished by exposing the ware to the conditions existing in one of the four steam tunnels called Prehardeners* Teraperat^es of abcut 2COF are maintained, which is near the optimum. Temperatures much in excess of this cause boiling of the slurry, and those lower than this decrease the rate of hardening to a point where it is slower than the pouring rate. . Prehardener temperatures are controlled by means of temperature recorders and controllers that actuate pneumatic steam values. Baffles prevent the direct impingement of the live steam on the molds, which would cause boiling of the slurry. * The length of time required to preharden the ware varies with the thicteess of the piece inasmuch as penetration of heat, into the mass is involved. The extremes are a minimum of 1.C0 hour for 1" thick ware to a minimum of 2.$0 hours for 3" thicknesses. There are two main reasons for prehardening the ware before it enters the cylinder. It reduces handling Froblezs, and it makes the interval of time between pouring and autoclaving much less critical. Vhen the molds contain a fluid slurry, extreme care must be exercised in transporting them to, and loading them in the autoclave. The facilities at Berlin are not conducive to smooth and gatle handling of the molds between the time they are filled and the time they come to rest in the cylinder. Iaylo-20 slurries do not preharden, and vath the smoothest handling possible under the conditions existing, a great amount of off-ware results because the slurry shifts from one end of the mold to the other or actually spills from the mold* The defect appearing in the product is listed as "N.E.K." (not enough material). On the other hand, when the slurry in the molds Is prehardened before the trip to the cylinder, it can withstand a reasonable amount of abuse* Thi is done for all Xaylo-10 ware both pipe covering and flat ware* The other important reason for hardening the slisry soon after casting is to minimise bleeding of water from the cast piece and/or settling of the solids from suspension* The extent of this action, of course, increases with time, and is more pronounced in large sizes in *hich the head of the fluid slurry is high* Scheduling of the cylinders so as to have one available to receive a train of filled molds just as soon as it is ready for autoclaving is seldom possible if the cylinders are to operate at peak efficiencies without undue downtime. Accordingly, a train of filled molds may have to be held on the floor for periods up to about four hours before a cylinder is available for this train calling for a definite autoclaving- cycle. Ware in a prehardened state can withstand eMg treatment without damage. In contrast, the length of time that non-prehardened ware in large sizes can 062 03as \ ( Ll2 remain outside tae cylinder without adverse effects is extremely limited. Within a relatively short tine, discontinuities appear in the form of veins of water, which carry over into the finished prccuct as cracks, anc- tears er separations; or the slurry nay subside to an extent that the prescribed dimensions are not net in the product* There is still a third advantage to be gained by prehardening. it peak rates of prccucticn, a fresh train cf ware enters the cylinder within minutes after a processed train has been pulled. Temperatures of the cylinder shell under these circumstances are in excess of UOOT. From the tine cf entrance until an atmosphere of saturated steam is created within the sealed cylinder, the mold metal receives a great amount of heat by radiation. If the slurry is still in a fluid state at this time, there is great danger cf boiling occurring at the slurry-mold interfaces, resulting in pitted and rough surfaces of the product. When the slurry is preiarcened, the risk of this happening is minimized. Surface boiling is sometimes experienced with the Kaylo-20 slurries, but the other problems which are attendant in the processing of a fluid slurry under eristdng conditions at Berlin are far sere serious. Ivery effort is made to get the cast slurries into the cylinder as soon as possible after pouring, but with the complications involved, too long a tine fre quently elapses. Since the Kaylo-20 products are made on the same lines as Kaylo-10 ware, the latter in all stages cf the process must be out of the way and not act as an obstacle in the path cf the Kaylo-20 naterial. Working back from the tine that a cylinder is scheduled to be available to receive a Kaylo-20 train, the following must be taken into considerations the mixers and lines must be washed free of Kaylo-10 slurry, the batch weighed out and mixed, molds stripped and available on the pouring line, . the Kaylo-10 ware in process ahead sufficiently prehardened and moved out of the preharcener, and the cylinder emptied and made ready to receive the cars of Kaylo-20 ware. Granting that all of this maybe done effectively in proper sequence with perfect timing, the molds containing the fluid Kaylo-20 slurry must still be transported over a devious, rough, 150-foot-locg path to the cylinder. ' If Kaylo-20 pipe covering is to be made consistently with low percentages of off-ware, a separate line from mixer to cylinder is essential. As it is now, it is produced on a line designed for a slurry of greatly different properties and behavior. Passage through the prehardener is an esaple of the incongruity involved. Heating cf the Kaylo-20 slurries in the prehardener not only does not accomplish the ends for which the treatment is designed, but actually has a detrimental effect. Heating to temperatures in the neighborhood of 200F results in more fluid slurries that are more prone to leak from the molds and also to slosh during movement of the molds. Returning to the prehardening of Kaylo-10 pipe covering, this would not be essential in. the production of many of the small sizes if it were possible to autoclave the ware within about two hours after pouring. Sizes up to about 8 inches exhibit relatively slow rates of bleeding, ary* can be transported without damage with .a reasonable amount of care. . This is men-- tioned because tests have shown that ware which has not been prehardened exhibits about 25% higher strengths than ware which has undergone this treat ment. In a sense, then, prehardeaing is a necessary evil with conditions as they are. A - _ _^ 01 062 03<39 13 \ Probacly because there is no alternative in view of the limited space available in the Berlin plants a car of molds is pushed into the prehardener as sc.-n as it is loaded. In this manner, the train is race up in the prehardener. This is bad practice for several reasons. In the first place3 full advantage is not taken of the purpose for vhich the prehardener is designed. The capacity of the prehardener is governed by the tine required to preharden the last car loaded. Therefore, it is serving r.ereiy as an accumulator for aE""preceding cars. In as far as functioning as a pre hardener, the tine auring vhich it is being loaned is vasten. A second bad feature of car by car loading is the less cf heat curing the tine the door is open to receive each and every car cf the train. Third, it is not possible to achieve uniform prehardening throughout the train. Obviously, the -ware in the first car receives sere heat than that in the last car. - But perhaps of greatest significance is the bunping and jarring vhich soft, partially preharaened vare receives as each additional car meets and shoves those ahead of it in the prehardener. At an interr.ediate stage of preharcening, tne ware has lost its plasticity and ability to neve vith and recover from mechanical shock, and does not yet possess sufficient strength to resist certain disruptive forces. Under forces that tend tc neve the partially prehardened slurry or to shift the core, cracks are apt to occur in the ware. Presently about 2C% of the eff-vare is due to cracks. There is every reason to believe that most of these originate in the prehardener. Naturally, the larger sizes of the lesser thmclmesses are core susceptible to damage. This cracking of the ware daring the prehardeuing step would not be tne problem it is if means were available for smoother handling, such as perhaps a monorail system. The obvious way to overcome the several disadvantages inherent in present practice would be to accumulate an entire train cutside the pre hardener and to move the train as a unit into it* This dees nou appear possible with the restricted space available at Berlin, but should be con sidered by all means in the design cf a new plant. Prehardener capacity pretty much controls the rate of production. An advanced state of hardness must be obtained: otherwise a high percentage of cracked ware results. Berlin has from time to time lengthened existing prehardeners to meet the demands of increased production. The limit as far as available space is concerned has been reached on i of the k units. In the design of a new plant, it should be made certain that prehardener capacity is in excess of ejected demands by a safe margin. The degree of latitude in formulation also is dependent upon prehardener capacity. The stiffening and hardening of the slurry at temperatures in the neighborhood of 200F is the result of chemical reaction between the diatomaceous earth fraction and the lime of the batch. It follovs that formulations containing less diatomaceous earth in proportion to .crystalline silica, all other conditions being the same>,vill preharden at a slower rate. Studies have shown that the limiting temperature the product can withstand is raised by a decrease in the proportion cf diatomaceous earth in the formulation. 01 062 03^0 Lh Presently Kaylo-10 thermal insulation shews a shrinkage of aoout 1.3? after being heated for 2k hours at 12C0F. The ratio of diatcnaceous earth to total silica in the batch is 0.7. Available data in-icate that if shrinkages of this magnitude are to obtain at 150C instead of 1200?, only aoout hCS instead of 70? of the silica of the batch can be in the form of diatcnaceous earth. This change vould recuce the rate of prehardening, vith currently available rav materials at least, to a point that the output of the present prehardeners vould be drastically curtailed. On the other hand, if the prehardeners were longer, or there were more of then, making it possible for the ware to retain in the prehardeners for greater periods of time, reductions could be made in amount of diatcnaceous earth vithout the pre hardening step becoming the bottleneck in the process. In determining prehardening capacity for a new plant, the prehardeners should be deliberately over designed, perhaps two fold, on the basis of the rate of prehardening of the present slurry. This vould eliminate the restrictions on formulation nev imposed by easting equipment. \ ( K 01 062 033J it5 Chapter 3 AUTOCXAVBtu A DP1T2JS Autoclaving of Kaylo products is accomplished is SID cylinders. SID is a convenient tern coined to designate a cylinder in vhich simultaneous induration arc drytng of hysrous calcium silicate products car be accomplished. The strict meaning of induration is hardening. In the processing of Kaylo products, it is the step in which the lime, silica, and water are combined to form the hydrous calcium silicate desired in the end product* The formation of this hydrous calcitn silicate structure brings about the change from a soft, pliable mass to a rigid body; hence the term induration. The reaction of the three components to form the desired hydrous calcimc silicate occurs under conditions of a ste a'Siosphere at elevated pressures and temperatures. Actually, it is the heat that brings about the combination of the components, but since water is one of these, a steam atmosphere is required to conserve this ingredient in the reactive mixture. A comparison of the formulae of the two hydrous calcium silicates in question, hCaO.5SiO2.5H2O and 5CaO.5SiO2.E2O, with the batch fcrmulaticns will reveal that the amount of water in the batch is greatly in excess of that present in either of the two compounds. This situation maxes it possible to begin the drying phase of the autoclaving cycle before the combination of lime, silica, and vatdr is complete without any danger of insufficient water being present for the reaction. Thus it is possible to carry on the induration and drying simultaneously - a "SID" operation. - Drying is accomplished by subjecting the ware to an atmosphere of super heated or unsaturated steam. Each cylincer is equipped with radiators heated by a flow of Dovthem liquid at a temperature of about 600? or somewhat higher and a fan at one end to circulate the heat through the train of ware. At a given point in the specific cycle being employed, the fan is turned on. The heat being thus supplied raises the temperature of the atmosphere surrounding the ware, causing water to evaporate frcm the product. In a closed system, an equilibrium would soon be established. That is to say, . for any given temperature the pressure would rise to the value equal to that of saturated steam at that temperature. When the equilibriira, or sat urated steam, condition was reached, evaporation of the water from the ware would cease. But in the SID operation, the pressure is maintained at a constant value by means of a control valve througn vhich the additional steam being generated escapes frcm the cylinder. In fact, the SID cylinder during the drying phase of the cycle functions as a boiler, the water for the generation of steam coning from the ware. This is literally true because the steam generated in the SB} cylinders is fed into a low pressure system which serves to supply steam for the prehardeners, to heat the plant, etc. A SIB cycle consists of four phases: time required to get up to pressure; time at 'pressure without the fan on (saturated steam.atmosphere); drying time (superheated steam atmosphere); time required to bring the pressure down tc atmospheric pressure. . 01 062 033a f \ ( U6 The first, or Tip to pressure, phase is fairly constant for a given cylinder and load and varies from 2$ to 30 minutes fcr pipe covering, and is 1 hour fcr flat ware tr.lns. A controlled raze cf pressure rise is acccsplished by a pneumatic control syszem composed of a tire-pressure can which operates the set point of the pressure ccuzroiler. The pressure controller throttles the steam inlet valves to obtain the pressure rise cut on the tine-pressure can. . The second, or indurating, phase is the period during which the ware is subjected to saturated steam at a constant and definite pressure and temperature. The length of this phase of the cycle is determined by a combination of many factors. Those that must be considered include: Nature of the hydrous calcima silicate desired - Kaylo-10 cr Kaylo-20; the thickness of the ware; the type of product - core, pipe covering, or block; desired end moisture content - "vet* or "dry"; the physical structure of the train; the operating pressure and other characteristics cf that particular cylinder. The indurating phase nay vary in tine frca zero to 1 hour. In general if conditions are such that an extended drying period, the next phase of the cycle, is to be in effect, the incurating phase is shortened accordingly. This is because there is ample water present fcr the chemical reaction that produces the hardening or indurating of the ware to continue far into the drying phase. The theory of SH) autoclaving presxm-.es that, at the start of the cycle, conditions are favorable for the reaction of lime, silica, and water to # advance to the point at which a rigid structure of hydrous calcium silicate has been set up before there is any significant less of water. Actually, this condition does not obtain with certain sizes of pipe covering in 1 inch and 1-1/2 inch thicknesses under present plant practice and rate of production. Within a natter of 20 minutes to one-half hour, the processed train is removed from the cylinder, a fresh train put in place, and the cylinder . door closed for the next cycle. During this time, the hot Dcvthem continues to circulate through the coils, and, of course, the cylinder walls rgnain very hot from the previous cycle. Although saturated steam is employed to bring the cylinder up to pressure, the temperature of the atmosphere within the cylinder is considerably above that of saturated steam at the pressures eristing at the beginning. Thus a saturated steam a-Sxosphere is not created, and as a result, premature drying of the thin sections of pipe covering results. This often causes excessive in-process shrinkage, and sometimes soft ends, where drying is more pronounced. Attention is now being given to means of correcting or minimizing this condition. It has been the practice to keep the steam trap at the bottem of the cylinder open at all times. It is now proposed to close the trap during the up phase and the indurating phase of the cycle, and to open it when the drying phase begins. This is an added operation and must be given close attention, but it is hoped that the results will justify it. The theory is that the incoming steam will condense on the relatively cool molds and cars, and this condensate then held in the cylinder to contribute to the humidity instead of being allowed to escape through the trap. 01 062 032>2> U7 A great amount of attention must be given to the make-up of a train of ware going into a cylinder. Ware of the same thickness, for the nest part, goes into the sane train. But crying characteristics depend upon the shape and other dimensions, as veil as on the structure of the loaded car. Ware on cars near either end of the cylinder is in a position sere conducive to rapid' drying than that on cars near the middle of the train. Consequently, the cars of vare nor difficult to cry are placed at the ends of the train. Care mist also be exercised in the location of the cars in the train so as not to create undue obstruction to desired flow patterns within the cylinder. At the end of the prescribed induration period, the fan at the end of the cylinder is turned on to carry heat from the radiators containing hot Dcvthern fluid over the vare. The length of this phase of the cycle is determined pretty nuch by the sane factors as those for the length of the indurating phase. The Process Control Supervisor and the Quality Control Supervisor jointly evaluate the cylinder' cycles each day from a mass of basic data acrraulated in the operation. Changes are made in the cycles where and when indicated to be advisable. Of particular importance in this connection are the moisture contents of the ware throughout the train and the strength and high temperature shrinkage of the product. The percentage of shrinkage shewn by vare after having been subjected to a temperature of 1200? for 21 hours is an excellent measure of vhether or not it has received adequate processing in the autoclave. High shrinkages are evidence that an opportunity had not been afforded for sufficient reaction to occur, and are even more sensitive than strength r data in this respect. The objectives in cycle design and adjushser.t are to produce vare of unifora high quality and of unifora moisture contest. "Dry" cycles are employed for pipe covering in 1" and 1-1/2" thicknesses, which means that all vare as it comes from the cylinder should have a moisture content very close to 252. Ware of greater thicteesses (except core material) is on "vet" cycles, which are designed to yield vare having a moisture content near 652 Ware frea "vet" cycles must receive additional drying in one of the four auxiliary driers. These are rooms in which a flow of air at about 300F is maintained by unit heaters. The sole purpose of this practice is to increase production frem the cylinders that are available at Berlin. Drying is not as efficient in the hot air driers as it is in a SID cylinder, but this scheme does permit some shortening of the cycles in the cylinders, resulting in more cylinder loads or cycles per day. The end achieved by the use of the four driers is about equivalent to that which would result from the addition of another cylinder with all operating on "dry" cycles. Were this additional cylinder available, there is little doubt that the production of the same amount of dry ware could be accomplished more econom ically than is nov the case. Drying in the SID operation, is more efficient than drying by hot air for a number of reasons. In the first place, superheated steam has a much greater heat content than air at a given temperature. It also has a great 01 062 0334 f \ f hd thirst or affinity for vater; that is, It is the nature of steam to "want" to go to the saturated state* Also of great significance is that temper atures cf 500 to 600? are more feasible in the SID cylinder than in a hot air drier* High temperatures for the crying of Zaylo ware are advantageous because a lesser quantity of heat is required to evaporate a given amount of water (heat of vaporisation decreases with increase in temperature), and also because the viscosity of the vater is less, thereby permitting the vater from the interior of the piece to migrate ncre readily to the surface where evaporation occurs* Drying in the cylinder has the advantage also in that the ware is already hot throughout at the start of the drying operation and does not have to be brought up from room temperature* The mechanism by which Kaylo ware dries is not generally understood* Practically all of the moisture is evaporated at or near the surface. Within the structure of Kaylo products is a network of extremely fine, continuous capillaries, which at the start of drying are filled with vater. The diameters of these capillaries are so small that the vapor pressure of the water in them is depressed tremendously* Accordingly, the boiling point of the vater in these capillaries is extremely high* Therefore, there is every reason to believe that vater does not evaporate frea the surface of the vater deep down in one of these fine capillaries. To escape it must migrate through these marrow tubes to the surface, and evaporate at this point. ' This drying behavior explains vly Kaylo-20 ware dries so much faster than does Kaylo-10 ware under the same conditions* The xonotlite structure of the former is more coarsely crystalline than the tobermorite structure of the latter. This results in capillaries of larger diameter that can deliver moisture to the surface more readily* Consequently, the Kaylo-20 product dries in from 1/2 to 3/h of the time required for a comparable piece of Kaylo-10 ware* The question has been raised as to why make-up air is not employed in the hot air, auxiliary criers at the plant to reduce the relative hmidity of the drying atmosphere* The answer to this is it is more important-from , the standpoint of drying to maintain as high a temperature as feasible than to bring about a reduction in relative humidity. In fact, the marimta relative hiaicity that can obtain in the driers operating at 300? and at atmospheric pressure is only about 20%. Under these conditions crying from the surface will be very rapid, and the time required to dry the piece as a whole depends upon the rate of migration of moisture from the interior to the surface* As mentioned earlier high temperatures speed up this migration* For the reasons just discussed, a plant should not be designed to include auxiliary drying as an integral part of the processing. To be sure, provisions should be made for such drying in cases of emergencies, and for drying of a wet train or portions of a train that result occasionally for one reason or another. For cases of this nature, it does not appear feasible to re process a train in the cylinder* On the other hand it should prove econom ical in the long run to have a spare or stand-by cylinder that could be put into service when another is down for repairs or cleaning, rather than - attempting to make up the loss of production by going to "wet" cycles on all the other cylinders. When no spare cylinder is available and auxiliary 01 062 0335 Ii9 r driers are already being used to near capacity (as is tbe present situation at Berlin), it is the natural tendency to continue using a cylinder long after a repair or cleaning job has been indicated* Prolonged operation of a cylinder that has lost much of its efficiency because of need of repair or cleaning, is, of course, costly. Returning to the SID cycles, after the crying phase is complete (the moisture of the vare reduced to a prescribed amount), the tiner starts the tine-pressure can wnach operates the vent to the low pressure systen valve and starts to depressurise the cylinder* After the pressure reaches that of the low pressure system, the controls switch free the vent to the low pressure valve to the vent to the atmosphere valve to continue the lowering of the pressure in the cylinder. At this point the fan is also stopped. The pressure continues to decrease until aUcospheric pressure is reached and the cycle completed. The standard down tines with pipe covering loads are 25 minutes for each of the three 175 psi cylinders, and 30 minutes for the two 200 psi and the seven 250 psi cylinders. - The rapid rate at which the cylinder can be safely brought down frea pressure is saoe possible by the ware being in a dry state. Formerly when ordinary saturated steaa autoclaves were in use, the rate at which the pressure was reduced was held at 1 psi/ninutej at faster rates the saturated ware would blow up. Herein lies another great acrantage of the SID over ordinary autoclaves. With SID cylinders cry vare can be produced at a considerably greater rate than can vet vare by saturated steam vessels. Then, of course, provision has to be made to dry all of the products from the latter type of cylinders. As mentioned earlier, hot air drying . is a prolonged and inefficient means of accomplishing this for fcyurous calcium silicate products. It is of interest that the J-2i plant at hanville has 16 crying tunnels, 170 feet long, equipped with U tracks per tunnel, having a total capacity for 1,800 cars cf vare. This plant has nine cylinders of the conventional type. . The 250 psi cylinders at Berlin are much more efficient than the 175 psi ones. The latter are remnants of early operation which have been con verted to the SID type* On an average, the total cycles in the former are . shorter by: 1 hour for l-i/2" thick ware, 2 hours for 2-1/2" to 3" ware, and 5 hours for 3-3/h" to u-l/h" thicknesses. Just what operating pressure would be the most favorable in plant practice remains to be determined. There is little doubt that it will prove to be higher than 250 psi, but how much in excess of this pressure is a natter of pure speculation. As the operating pressures (and temperatures) increase, the rate of reaction increases, as should the rate of drying. While the degrees of superheat at 600F (difference between 600F and the temperature of saturated steaa at a given operating pressure) will decrease as the operating pressure increases, this should not in itself result in slower drying within practical ranges of pressures. The higher temperatures that will exist throughout the ware should more than offset the effect of fewer degrees of superheat. r 01 062 0336> 50 On the other side of the picture is the longer tine required to bring the cylinder up to pressure and to depressurise it at the end of the run. The tine consumed in accomplishing these two phases of the cycle could be appreciable at certain high pressures, and ncre than balance the gain in tine possible for the indurating and drying phases of the cycle. The Research Laboratory at Newark is obtaining an experimental SZD cylinder capable of operating up to 500 psi. For the first tine equipment will be available to conduct experiments to determine optimum SID conditions and to obtain seme badly needed information. It is likely that the limiting factor in regard to operating pressures will prove to be the cost of the equipment designed to handle such pressures as veil as certain other added costs involved in operating at pressures which are unccrmon for vessels of this size. 01 062 033^ 51 Chapter X OPmdATICNS SuBSBQUJlT TO AUTCCIATTIG After the vare emerges from the autoclave, and is in a dry condition, it must undergo triming and finishing, warping, packing, am storage in the warehouse* Of course, the ware is inspected by Quality Central at a_v> of these stations* If discolored or rough surfaces are detected at the trim saw, this ware is taken out of the line for hand clearing and smoothing of the surfaces before it is sent on for wrapping* The handling of the vare after it leaves the autoclave is the most inefficient of all of the operations at Berlin* This is probably the natural result of the plant having evolved for the most part, from a sand-line brick plant to one producing Kaylo products* The inefficiency is strikingly evident when one considers that a given piece of ware casing free a cylinder on a vetn cycle is likely to be handled or renoved frua one location to another, singly or in a container of sene sort, 16 separate tines before it is on its way to the customer* A comparison of Berlin and Maaviile operations in this area reveals a startling contrast* It must be said that management of Berlin is aware of these deplorable conditions and has given GPD Engineering the project for conveyor and equip ment from trim saw to vrap and pack area* On the conveyor all pipe covering will be end triraed, if for only a HJdnsB to produce square ends. On the same conveyor, the pipe covering will be brushed to remove discolorations and bumps resulting fren dirty molds. The adhesive will be applied mechan ically. The wrapping will be done by hand, and carton sealing will be accomplished by top and bottom sealers* This project is excellent as far as it goes, but a material ha-d-ling engineering study should be made of the complete operation to determine how the general condition at Berlin could be improved, and to come up with recoumendations in this respect for a new plant* That there are 23 lift trucks continuously moving throughout the Berlin plant in an apoareat helter- skelter fashion, is illustrative of the problem. Aside from other obvious undesirable aspects, a considerable amount of danaged vare results from this manner of handling* 01 062 0333 / 52 Chapter II AOIHIAP.T C'?"ATIC:S Naturally, there are marry supplementary operations connected with the proauction of Xaylo products that are sore or less cannon in the manufacture of any article* These will not be discussed. There is, however, one such operation that is peculiar to the subject process. That is the cleaning of molds* The method now employed involves the use of an inhibited acid to dissolve the adhering calcium silicate* Back in 1950, as part of the investigation of SID possibilities, 0-1 Research conducted studies of various mold cleaning methods. The recorrcendation was made that acid cleaning be dropped from a^ further consideration because of the many objections inherent in this method* For seme reason, probably because of a relatively high initial cost of an alternative method that was recomsended, this advice was unheeded by management and acid cleaning was put into operation. The result has prompted the Plant Manager at Berlin to write on April 5, 1959: "The cleaning of molds with the use of acid must be eliminated at the earliest possible tine for two reasons: first, the mold equipment has new been subjected to acid attack for sufficient years that the rate of deterioration is becoming greatly accelerated* Unless this is stopped, large replacement costs for molds will be encountered. Second, everyone is familiar with the aforementioned labor costs* incurred, which cause is based on the use of acid for sold cleaning. We had a Pangborn** representative in last Friday, ` and all past work that was done was covered in his files. This goes back as far as 1950, when Research of 0-1 conducted the ecperiments. The cleaning of the molds will be done by a soft abrasive blasting, using walnut shells. Pangbom has had many installations of this type of blast cleaning. They . also have the design, which was designed long before and never followed through--. This reduces all of the etching of the shells (molds) and also eliminates the cost of acid and allied material cost. It will eliminate the manpower aforementioned, as well as reduce manpower in Mold Repair for cleaning and repairs necessary. It will increase the run life of the molds before cleaning is necessary. The blasting is done with rotating wheels throwing the abrasive against the mold rather than using high pressure air, which calls for a large air compressor cost of installation and operation. We are sending out a shell (mold) for them to again check the buildup (deposit) to make sure that the machine will efficiently do the job* *Cost of band cleaning stains and removing rough surfaces, both the result of acid cleaning of the molds, from a large portion of the ware. **The method recommended by 0-1 Research. 01 062 03S9 53 This is a four-wheel Job am the cost is roughly 510,000 per vheel, which of course includes the entire installation, however, it should be in the area of $35000 or a little less. The machine has to be set in a pit and will hare conveyor holding of adds into, through, and out of the blast cleaning area. We will follow this project diligently and with dispatch, and as socn as design cost, tine of manufacture, installation time and cost are secured vill follow through with a 901." Along with the acid cleaning, the other methods studies by C-I Research, and not reccmended for one reason or another, were: High pressure steam; high pressure water; mechanical brushing; supersonic vibration. The cleaning of molds would not likely be a problea of any consequence if they were to be made of stainless steel. A few replacements hare been constructed fairly recently of this metal, and the performance in respect to buildup and the surface of the ware has been remarkable. After about two months of service, the metal still exhibits a mirror-like appearance. If the present behavior continues over a prolonged period of time, the economics involved should be evaluated. An unfavorable answer would probably result in the Berlin situation, in that it would likely be poor economy to merely replace the black iron shells with stainless steel, thus duplicating molds that are too short. But it may be a different story if new frraes and new molds were to be fabricated for use at a different location. 01 062 03VO Chapter XU INDICATED MODIFICATION Or rESSINT PROCESS AN EQUIPMENT 5u At no comparable period in the history of the Kaylo operation hare so many changes and inprovenents been made as in the past fev months and weeks* Although the writing cf this manual has been done at intervals over a period of no more than sloe weeks up to this point, many cf tne changes indicated in previous chapters as being desirable have already been accom plished and in operation. Furthermore, several others are scheduled for early completion. On the assumption that these, too, will be in effect before this manual is in the hands of the reader, no further mention will be made here. The items that are listed in this chapter are these likely not to be in operation in the very near future because of the magnitude cf the project, lack of manpower and/or space at Berlin, or other valid reasons for the delay. At the risk of appearing repetitious and redundant, mention will be made of certain subjects for the sake of emphasizing their importance. They should be considered from the standpoint of feasibility of inccrpcr&ticn at Berlin, and should by all means be taken into consideration in the design of any new plant* In this latter connection, Berlin experience is providing and will continue to provide, valuable information in respect to process and equipment. Contrary to the situation in many plants, there is very little or no conservatis.ia the attitude of the management of Berlin. Bather than being averse to any change, there is an expression of desire to try anything new if it has at least a 50*50 chance of being favorable frem the standpoint of cost savings, increased production, or quality of the product. With this foreword, further discussion of certain itecs follows.. Seoarate Production Line for Kavlo-20 Ware In the present set-up, Kaylo-20 ware is mace on the same line as Kaylo-10 products* This all too frequently results in an excessive amount of off-ware. The Kaylo-10 line is designed to handle prehardened material. Kaylo-20 slurries do not preharden. The long route that the molds filled with a fluid slurry must follow - including passage through the prehardener - results in shifting of the slurry, causing the end product to be out of dimensions. Not only this, but the Kaylo-10 slurry and ware in all stages of the process, freer mixer to cylinder, trust be cleared out of way before Kaylo-20 production goes through. This results in waste of time even under the best scheduling possible* The line for Kaylo-20 products should, of course, not include a pre hardener, but should provide a shore, smooth passage frem pouring station to the cylinder. "' 01 062 03V/ v_ Separate fixers for Kaylo-20 slurries would eliminate the necessity for vashing the sixers and piping free of Kaylo-10 slurries when runs are to be made. They would also make possible a reduction in the number of batching operations. Under the present practice, the sine of the batch must be tailored to the volume of the molds in the particular train being processed at the time. Since Kaylo-20 slurries do not preharden and may be held indefinitely, a large quantity of Kaylo-20 batch could be mixed and drawn uoon as needed. Conveners It vas mentioned in a previous chapter that movement of materials and ware throughout the Berlin plant is accomplished by a fleet of 23 lift trucks, . and that a materials handling engineering study is indicated. Discussion here is limited to the handling of the filled molds from pouring to cylinder, because rough handling during this stage of the process contributes to off- ware. The sloshing of the fluid Kaylo-20 slurry was mentioned in tbs section above, but damage can also result to Kaylo-10 ware. At certain intermediate stages of prehardening, Kaylo-10 material has lost its plasticity but has not yet attained any appreciable degree of cohesion and strength. Mechanical shock can easily cause cracking. In the present practice, filled melds are loaded on cars with flanged wheels to run on a track througa tne preiirdener. A train of cars is made up in the prehardensr, the ware receives burping and jarring as each car is added to the train. Once the Kaylo-10 ware has been prehardened sufficiently, it can withstand a reasonable amount of mechanical shock, so smooth handling of the ware in the prehardener is of greater importance than on the way from there to the . cylinder. But smooth handling of the fluid Kaylo-20 slurries is required V. over the entire route. A different and smoother means of carrying both Kaylo-10 and Kaylo-20 ware through the prehardener to leading in the cylinder is indicated. A monorail system, for example, may be the answer to the problem. . Accumulation of a Train Prior to Prehardening The disadvantages inherent in the practice of up the train of ware inside of the prehardener have been discussed in Chapter VIII. The favorable results likely from accumulating the train prior to entrance into the prehardener were also outlined. Prehardeners have in the past been the governing factor affecting the rate of production, and can also limit the latitude of batch formulations if the capacity for output is restricted. Under present conditions of formu lation and rate of production, the prehardeners are in fairly good balance with the rest of the processing. But conditions could change and the pre hardener capacity could become a bottleneck. For reasons discussed in detail previously, a prehardener would function more effectively if it were to receive an entire train of ware as a unit instead of one car at a time. Hat is to say, a given prehardener could preharden a given train of ware in a shorter period of time if means were provided for the make-up of the train before entrance into the prehardener. 062 03VoL ( V 50 Along with an arrangement of this nature, means should be provided to perr.it the by-passing of the prehardener if a~d vhen the site of ware and availability of a cylinder indicate such is possible and acvisscle. This in itself would have the effect of increasing prehardener capacity in relation to the other production units. Reserve SZD CvLinder Cacacitv At present, in an effort to obtain the utmost in production frcn existing cylinders at Berlin, most of the ware is taken from cylinders vhen the moisture content is about 65?. This ware then must be dried further in the much less efficient auxiliary driers. In addition to this less in efficiency, the cost of extra handling of the ware must be ccnsicered. If an additional SID cylinder were available, the same amount of dry ware could be produced at less cost. It would likely prove to be good economy to have a spare cylinder available for use vhen one of the others is down for repair cr cleaning* At present, the withdrawing of a cylinder fres production is postponed as long as possible because of the production problems involved. In other words, it is kept in operation long after a decline in operating efficiency is evident. With a spare available, *vi cylinders could be maintained at top efficiencies without interruption of production. This spare cylinder need not be down all of the time it is not called upon to replace another, but could be used to receive at least a portion of the Kaylo-20 ware poured on the separate Kaylo-20 line mentioned earlier. However, there should be a clear understanding among *31 concerned that its chief function is that of* a spare, and should not be Inflexibly tied in with production. Auxiliary Driers It is not the intention of the preceding section to imply that some - auxiliary drying facilities are not necessary. The point is that it is not good practice to employ this type of drying as a routine matter. On many occasions seme of the ware ccsing from a "dry" cycle will have a higher moisture content than is permissible for dry ware and this ware will have to be given further drying* Mechanical failures, failures within the Dowthera system, etc., could sometimes result in an entire train of vet ware. Under conditions such as these, it is more feasible to dry in an auxiliary drier than to return to a SID cylinder. Mold Cleaning; The present method of cleaning molds with acid is costly, and after a time results in serious damage to the molds. An alternative method must be found. Studies of several years ago indicated that an effective and safe Job could be done by blast cleaning with a soft, organic abrasive. The plant has Just recently begun further investigation of this method. Oi 062 03^3 / t r V. yt Inorcvements on the hour Line There are several improvements Indicated on the pouring line, and concerted efforts are being maoe to put them into effect* Among these aro: Keans for accomplishing complete removal of Kaylo chips ana dust from mold cavities prior to filling; mechanical oiling of molds; full length pouring devices; mechanical screening* ' Perhaps the greatest benefit to be derived from these items will be the elimination of much of the human element and the role It plays on the pouring line in respect to rate of production and the quality of the ware. Holds The ma^or shortcoming of prtaezit pipe covering molds is that they are too short* If the molds were longer {in the neighborhood of 37*)* all pieces of pipe covering could be given an end trim* Less off-ware would result, and even passable vare would generally be Improved in quality* The econmics should be studied of constructing the shells and cores of pipe covering molds of stainless steel* Trials in progress indicate lack of attack and freedom from build-up. Preference of stainless steel over black iron nay depend upon whether or not acid cleaning is continued* 01 062 034y ( Chapter XIH pertinent reports Several detailed reports have been Issued that are pertinent to the subject natter or this manual* Those that are most closely related are listed beiov. Copies are available at the desk of the author of this manual, and another set is on file at the Berlin plant* Title Author Date Development of and Experiments vlth the b* x 21* SID Cylinders at Berlin Clarence D* Pavlicld. 8-1-52 Development of Kaylo Batch Mixing Procedure at Berlin Plant Harold ?. Zink 6-15-54 Effect of Asbestos Variations on Riysical Properties of Kaylo Thermal Insulation Establishment of Cycles for l8, 2", and 3U Pipe Covering in the SH) Cylinder at Sayrevilie, K. J* Factors Affecting High Temperature Shrinkage of Kaylo Thermal In dilation D, L* Bishop Harold F. Zink D L Bishop 11-4-55 8-1-52 4-8-53 Factors Affecting Thermal Conductivity of Kaylo Insulation V* C. Taylor Factors Contributing to Off-ware at Berlin Harold F* Zink 8-20-57 5-7-54 Investigation of the Effect of Variables In the ftpehardener Operation on the Quality of the Ware Harold F Zink 8-5-54 Johns-Kanville Ihexaobestos Plant Visitation * B* S* Grant 7-10-58 Kaylo Hold Design, Filling, Cleaning, Stripping, and. Lubrication Clarence B* Paulicte. 8-1-52 Kaylo Manufacturings Process Operational Control C. F* Silktfood 6-11-58 Kaylo Bay Materials and Processes Observations of the Flat Ware Process at the Berlin Plant During the Weeks of November 9 and November 30, 1953 G* L* Kalousek Harold ? Zink 10-13-52 12-22-53 01 062 03</5 -S*-' -. ' 59 Physical and Chemical Properties of Kaylo Products G. L. Kalousek No. 1 Production Line Training Manual Va. ? P-ortue+.*>: nn T.-i np TVs-* m Manual A. D. Denny A. D. Denny Revuev of Berlin Plant Operations 0. V. Pfeifer Sayreville SH) Demonstration Plant; Background, Design, and Performance Clarence D. Pavlicki Studies of the. Effect of Reactivities of Various Diatoaites in the Reactions of Formation of Saylo and Kaylo-20 A. S. Ayish Studies of Molded Pipe Covering Off-ware at Berlin plant D* L. Bishop Study of Molded Pipe Covering Off-ware at the SayreviHe Plant W. C. Taylor Study of SH) Cycles at Berlin Plant and.Other Factors Affecting the Quality of the Ware Joseph Scovronek The System Lime^Aluaiaa-Silica-Water and Applications to Kaylo Products G. L. Kalousek The Systea Line-Silica-Water G. L. Kalousek Trial Runs of Zonotlite Kaylo at the Berlin Plant, and Properties of the Product W. C. Taylor Vertical Casting, Prehardening, and H. F. Zink Ejection of Kaylo Molded Pipe Covering C. D. Pavlicki Vertical Casting, Prehardening, and Ejection of Kaylo Molded Pipe Covering Section II C. D. Pavlicki H. F. 2ink Zonotlite and Lepisll Kaylo Products G. L. Kalousek 10-13-52 5-17-5L 2-22-5U 8-30-56 8-1-52 1-28-58 3-16-53 12-23-52 1-21-5U 10-13-52 IO-13-52 3-5-55 5-7-53 10-19-53 10-13-52 01 062 03V6> \