Document kmZvmjj69dz3Dgm47Xz67paMn

FILE NAME: Ameron (AME) DATE: 1964 DOC#: AME101 DOCUMENT DESCRIPTION: NSC Transactions - Article by VP of Amercoat Coating Hazards National Safety Congress Transactions GENERAL SESSIONS ANNUAL MEETING O F MEMBERS CONGRESS BANQUET ; LIST O F EXHIBITORS GENERAL INDEX O F ALL VOLUMES N ATIO N AL SAFETY C C 425 N . Michigan Avenue Chicago, Illinois 60611 1 f . J i I I/orixe Scclvm COATINGS AND THEIR SAFE APPLICATION There lis no -By C. G. MUNGER Vice.President, Amercoat Corporation, Brea, Calif. / doubt that there are dennite tanker has increased manifold. Many of hazards in the application of coatings to the these chemicals are corrosive or require coat interior oi closed spaces such as are found ings to prevent contamination from iron or aboard ship. The use of synthetic resin iron oxide. Such materials are the ketones coatings for specialty linings aboard ship has such as acetone, methyl ethyl ketone, and greatly increased the number of areas where methyl isobmyl. ketone; aromatic solvents coatings are used. These linings have be such as toluol and xylol; jet fuels, glycols, come necessary due to the many new chem caustic solutions, vine, sugar, syrups, alco ical ladings now transported. This in itself hols, and many similar products. tends to multiply the frequency of possible accidents. That the hazards in applying coatings are real is demonstrated by the fact that there have been several fatal accidents __in the last fifteen years. The tankers, being built today require linings even for gasoline and other refined petroleum products, and many different coatings are used which were unknown to the marine industry a few years ago. By the On the other hand the safe use of haz ardous materials is dependent upon the eco nomic need for the product. If this need use of these linings not only Is the corrosion to. the interior of tanks decreased, but the quality of the products is maintained at justifies the precautions and protective equip refinery standards. ment required to maintain saie application conditions, tf.cn proper safety methods can be developed which reduce the hazards in volved. Coatings such a vinyls, varan, epoxies, polysulfides, phenolic epoxies, and inorganic zinc coatings are now commonly applied, and each type of coating has its own character There are two excellent industrial ex istics. These are primarily applied to the amples of this: one is the explosive in interior oi tanker tanks although there are dustry. and the second is the development other enclosed spaces aboard ship' which and use of atomic energy. In both of these also require .coatings. Chain lockers, deep areas safety precautions were developed wells, void spaces, and doable bottoms all which reduced the hazards of working with difficult materials to urn alssutute minimum. The marine mdti-trs. istriirularly the tanker u-e actin g s which can provide difficult safety conditions. Aikyd. coal tar, and asphalt cutbacks are cornmnn in these a ro s. or petroleum traiisivrtation division, lias .dsn maintained very high safety, standards iue to (Ik handling of many flammable and explosive liquids. The following table li*ts some of the rharaclrristics of commonly applied coatings which bear cn their safe application. It will lie noted that the MAC (Maximum Allow The mating hazards we are concerned able Concentration) of all listed except the with here, however, dr, not involve the tanker inorganic zinc silicate is in the range of ojierators since once the crating are applied, 100 to 500 I'PM. This indicates that from they actually reduce the possibility of fire a health standpoint all organics are approx or explosion by providing a surface coating imately equal and that protective equipment which is easily gas-freed. The surface coat must lie used for the application of all in ing does not accumulate and retain hazardous confined areas." liquid o r fumes such as is the case where heavy rust films are built up rat unlined tanks. The potential hazards exist then in the Once it .was realized that there was a greater and greater need for coatings and linings in industry and the marine fields, a research program was established at Battelle shipyard or where the enclosed spaces in Memorial Institute in. Columbus, Ohio, to hit are being coated such as in drydock develop methods for the safe application of nr along outfitting docks. In the last few coatings in enclosed area. The aim of the years the transportation of chemicals by program was to determine a practical method 23 96i tialional Safely Congress TABLE 1 Characteristics of Commonly-Applied Coatings Type Vinyls ' Sunn Epoxies Reals Solvents High molec Ketones and ular weight aromatics chlorinated hydrocarbons selfcx Uncuiahlsg ' High molec ular-weight cM frlajgd nycsiKSsiPSw self-ex-' tlugulahlng Ketones and aromatics Will support Ketones and combustion aromatics A n h alt Sllaonlte Cutback Coal T ar Cutback Alkyda Will support combustion Flammable Flammable Inorganic Inorganic Zinc silicate non Silicate flammable Aliphatic o r aromatic petroleum ' Aromatics Aliphatic or aromatic -petroleum "Water Flash Point Open Cup 3W OT 0-10T 30--js * r 1M T+' -I0 T lOtfF None Explosive U n it . Solvents 1.31018 100 KAC Toxicity Resina Nontoxlc U to 3.0 300 XAC Nontoxlc 1.3 to 1.3 U 100 KAC 200-5001UC S aneM ui dennstiUi in sensttlve lndleldusls Nontoxlc U to 127 200 KAC U 200400 KAC Severe skin irritation SonIrritating None Silicate, mildly alkaline U nited skin irritation of application of these coatings' with simple rules tliat any painter o r applicator could understand and easily follow from writlcn irntmetinn. By following these rules, the applicator could be certain that no explosion could occur and this fact was Vt he proven h) BaiteRe's tots. Tlie liaranl iound in tile apjiiication of routings in mrhwcd arras can he placed in. three r kmifirstions: 1. Danger by tire or explosion. 2. Damage to the applicator from inhalation oi tlte various solvents used .in the cattlings. S. Dermatitis caused by contact with resins or solvents used in .the coatings. The starting point in the test program was the determination of the lower explosive limit not only of the individual solvents but oh tlte combined solvents as they were used in coat ings. The tower explosive limit of the in dividual products could be obtained from literature; however, little or no work had been done on the explosive limit o i combined solvents to determine 'whether a-greater or . lesser h a a rd existed from these mixture The lower explosive limit of au> solvent or combination of solvents maj le ilehneil for the purpo-c of this paper u Die unonot of solvent vapor in air which juii letuw the point at whirh an explosion will usviir if the air and solvent mixture is ignited with a sjork. This lower explosive limit oi the air amt solvent mixture, is exticmclv important in a safety study bemuse if the lower explosive concernration, of solvent in air is not reached, then no explosion can occur. While flash point is often a more com mon point of reference for safety than ex plosive limits, the lower explosion limit fig ures are mure important in a safety program dealing with coating application since the primary means oi maintaining safe applica tion conditions is through ventilation. Part oi the program at Batlclle was to devdop. a piece of laboratory apparatus from which reproducible results could be obtained for the explosive limits of both individual sol-' vents and solvent mixtures used in coatings. 1 I farine Scairn The following two table* show the lower explosive limit developed by the above ap paratus for individual solvents which are used in various coatings as.well as for combina tions of solvents which are typical of specific types ut coatings: TABLE II Test Explosive Limit Data for Individual Solvents Material Ethyl Alcohol Isopropanol ... Aceton* ............................................. Methyl Ethyl Ketone......................... Methyl laobutyl Ketone................... . Cyclohexanone ............................... n-Botyl Acetate ............................... 1-Kltropropuc .............................. Aromatic Petroleum (tiiii railcel. Aromatic Petroleum Ixylot rance).. Petroleum. Naphthenic friction....... Mineral Spirits ............................... Spark-Exploalon Limit. % Vapor by Volume la Air . 3.31 2.5* . No limit found . No limit found 2.SS 2.15 IM 1.43 15? ' Z32 2M 113 L23 . No limit found UO Pressure mm Hg 730 760 665 743 T60 780 760 760 780 780 . 780. 780 760 82 780 Temperature. 77 77 122 122 77 77 77 122 122 122 122 122 122 122 1 TABLE III Test Explosive Limit Data on Mixed Solvents , Material Spark-Explosion Limit. % Vapor by Volume In Air Ketone Aromatic Thinner............................... Ketone Aromatic Cleaner............................... Wash Prime Solvents..................................... Vinyl Tank Lining Solvents............................ Vinyl Boottopping and Topside Solvents........ Asphalt Gllaonlt* Solvents.............................. Epoxy Eater Solvents...................................... Tank Lanin* Epoxy Solvents...................... Phenolic Tank Limn* Solvents. . LIS 1.6* 1M 140 US Xo limit found Xo limit found 148 140 . Pressure. mm B e 710 710 710 7B0 7*0 7eo 7n 7X0 710 Temperature, _ T 81 M M as 77 VI is * fl It will be' noted tlut tlie mixed solvents arr generally in the same range as. live individual solvents. However, they' are higher in value than the lowest single solvent and below the highest. A second step in the study of these methods of safe application of coatings was the determination of actual evaporation rate of the. solvents from the individual coatings. While it is easy to visualize the maximum evaporation of solvents at the time of spray ing on the surface, nevertheless the coating must be applied as a liquid; and therefore solvents evaporate from the liquid state of the coating over a period of time. This is an important factor in safety as proven by the fact that accidents have oc' cuffed even though proper ventilation equip-' ment was installed during the time of appii- valitai lit w e ilidawr as silt as the noting >f the lank was tuniplftr, lV ventilation equipment w r Wised troni this tank to another ,ti>^ start dating application there. Approximately an hour later a workman laid a piece .of steel across the Itateli open ing and applied an acetylene torch to cut it to shape The hot metal dropped down into the tank and an explosion occurred im mediately. The explosion occurred, oi course, as a result of the evaporation of the sol vent from the coating during the drying period after application and after the ven tilation equipment was removed. Two charts follow: Chart 1 illustrates a 5-coat vinyl lank lining and Chart 2 shows a 5-coat epoxy tank lining. The evaporation rate for each coat over a period nf approximately, four hours is shown. 27 f r Marine Section there is no ventilation to dilute the solventair combination. Another factor which must he considered is the density of the solvents compared to air. This is shown in Table V, and in every case it will be noted that the density of the solvent vapor is substantially greater than that of air. with a very low Rash point will have a relatively high tower explosive limit. This is demonstrated by acetone with a Hash point of 0*F and i lower explosive limit o f 2.15 while turpentine has a flash point of 95' K with a lower explosive limit of 02. If the amount of solvent vapor is the TABLE V Properties of Flammable Liquids Used in Paints and Lacquer* A c e to n e ............. n-Amyl Acetate u-Aoyl Alcohol. n-Butyl Acetate .. . n-Butyl Alcohol ... Ce&Molve............. Celloeolre Acetate Cyclohexanone . . . . Ethyl A cetate....... ' Alcohol . . . . Gasoline .......................... n-Hexane ........................ Kerosene ........... . Methyl Alcohol ............... Methyl n-Btitrl Ketone.. Methyl laohutyl Ketone.. Methyl Ethyl Ketone.... Methyl n-Propyl Ketone., Mineral S p irits............... Naphtha, Coal T a r.......... Naphtha, Safety Solvent. Naphtha! V.M. A P ........ n-Propyl Alcohol .......... Isopropyl Alcohol ........ Stoddard Solvent .......... Totoeno .......................... Turpentine .................... o - X y le a e ........................ r Cloned CUP a 71 3 7* tt . . tot 134 117 S IS 300-1S5 -50 -T ice-us S4 't t 30 uo-iio 100-110 100-110 20^5 so lao-iio 40 M a Open Cup n uo M 110 uo us ... , , in 96 , # 0 ... . .. K . 60 a *46 *75 %by Volume in Air Lower Upper 2.15 12.0 1.10 ... 1*20 ... 1.40 2.0 1.70 1.70 1.5..0. 2.60 15.7 1.71 it lV.S 3.23 10.0 1*30 6. 1.35 it . 315 1.21 1.0 L34 2.0 1.81 11.5 IJ66 8.2 1.10 6.0 L10 5.0 1. 2.80 5.0 150 I 1.10 c.o 1.37 7.0 0.80 * ... 1.00 .... Density (Air-- LOO) 00 4.49 3.04 77 4.00 55 3.10 4.73 13$ 3.04 1.5* ' a- 97 J .ii 145 145 41 9* ... 2.07 2.07 3.14 3.66 Bolting P o t r 13 300 90 17 343 375 X13 SU' 171 171 100-4& 155 147 252 244 I7S at 300-400 300405 300-400 212-331 207 300-4i n00 331 300 391 T his indicates - in complicated lank .or drrp lank* such as arc common alsurd ship litat the solvent will lend to arcumuiatr in low areas and that tile explosive limit nut) tie reached in pockets whereat the soltraf-- air cnnhitiatron in the tank generally vvmiM lie less than the limit. This point cannot I over emphasized when it is cnmtiinril with the fact tin t the solvent evaporation from any of these coatings ui governed hy time. Even though there might not be suf ficient. solvent left in the coating to create an explosive, condition in the entire tank, it is possible to build up a solvent concentra tion in a limited area in the bottom of the tank which could be hazardous. Note also th at this chart compares the flash point with the lower explosive limit for the solvent. In many cases the solvent criteria irrri*ctivr ut the temperature (and this would lave to 1 assumed in calculating the amount of ventilation required in any given tank) the solvent with the higher explosive limit would be preferable for use in coatings. .Ml of the information so far has shown fla t ventilation or dilution of the solvent vapor' from the coating ie the most foolproof method of .eliminating hazards. This is in dicated by the statement that if the lower explosive limit is never reached, there can lie no explosion. In order to maintain maximum safety, however, it is necessary to properly ventilate tanks since they are usually deep and complicated in structure. Often the practice is to place a blower in a tank opening and to blow air into the area where coating work is taking place. 29 1 f i: f. t i . 1964 Xalional l| /rfy Congress Generally this is an unsatisfactory procedure if the blower is located at the opening oi the tank without an extension trunk. The air is circulated only at the opening and does not move or dilute the air in other portions of the tank. If a trunk is extended from the blower into other portions o i the tank, it tends to create a turbulent condition which again does not remove the solvent from all areas of the tank. It has proven to be much better procedure to exhaust the air from the lowest portion of the tank, making certain that the openings '' ^ I in the top o i the tank are free so there is adequate access of air into the tank. Since the solvent vapors are heavier than air. the air coming in a t the top tcods to.wash down through the tank, carrying the solvents with h, and the maximum concentration of solvents is removed rapidly from the lowest point. Using the recommended ventilation sys tems. together with the rate of evaporation and the lower explosive limit of the combined solvents, the following table was made up ior various sizes of tanks in which the blower size and th number of air changes per minute are recommended : TABLE VI Recommended Ventilation for Varions Sized Tanks ,5.000 sal*. J0.000 gal. 23.000 (ala. 50,000 sala. 100,000 sal*. 2S0.000 calf. 400.000 sala. 13.500 bbla. 37.000 bbta. 50.000 bbla. 668 1.23$ 3.243 i(M 13L37S 33.430 53.500 75J00 151.600 280.000 6.7 13.4 33.4 64.1 133.6 334.2 535.0 7510 1516.0 2900.0 9C Si 30 6 .53 M0 6 1.30 HO 10 2.60 3.80 10 5.30 ' M0 10 13.00 0.77 .80 0.48 X 21.40 0.34 60 51.10 0.26 5ft 106.30 ai4 SO 3 1.000cts. ft. 6 2.000ca. ft. 8 2.000cu. ft. 16 3,000cu. ft. 31 5.000eu. ft. 40 30.000eu. ft. 10.000cu. ft. 35 25.000eu. ft. 35.000 c u .f l. 230 50.000cu. ft. tOafcooda coeds L.7 Balautra 22mlaate* 27 ailantoi Umlaut** 14 alaotcs 3.0 minutes flSmlauUa 5.6 minutes The second hazard found in the application of coatings in enclosed areas concerns damage to the applicator from inhalation of the various solvents in the Gratings. It is well known that solvents of all types in paints, varnishes, lacquers, and synthetic resins should not be breathed continuously for extended periods of time as possible harm to individuals can occur. The solvents used 30 in synthetic resin coatings however are no more toxic dr anesthetic than many o f those used in prints, varnishes, and enamels. This is demonstrated by the following list of solvents taken from Dangerous Properties pi Industrial Materials by K. 'Irving Sax, 1937, showing the maximum allowable concentratson (MAC) of the various coating solvents based on an eight-hour day exposure. r Marine Section TABLE Vil day after day which is the criterion of Substance Acetone Benzol n-Butanol n-3utyl Acetate Butyl Cellosoive Cellosoive Maximum Allowable Concentration -1 0 0 0 33 100 200 200 200 chronic effect." In addition the ketone solvents, the pri mary Orths in synthetic resin coatings,.are rated a "warning" solvents. There is a characteristic odor from these solvents, and before a dangerous concentration is reached there is mild irritation of the eyes and mucous membrane, warning the workmen to get away from the area before the Cellosoive Acetate 100 solvent concentration becomes too high. Ethyl Acetate Ethyl Aleohol Ethyl Ether Gasoline Isopropyl Alcohol Methyl Ethyl Ketone Methyl Isofautyl Ketotic Naphtha (Coat Tar) Naphtha- (Petroleum) Stoddard Solvent Turpentine Toluol Trichloroethylene 400 The answer to this second safety prohtem 1000 is proper individual ventilation apparatus 400 for each workman applying the coating. 300 There are generally compressed air masks 400 and there are numerous types which supply 200 a continuous volume of dean uncontaminated to o air to the man applying the coating in the 200 lank. By proper use of such equipment a 300 . man may work for several hours in an en 300 closed area without the inhalation of any of 100 200 the solvent fumes. 200 Tlie third problem which may arise in the Xylol 200 application of coatings to ships tanks is that of resins which may cause irritation or While the maximum allowable concentra tion of aromatic hydrocarbons and turpenes such as toluol, xylol, and turpentine is in the same range ot maximum allowable concen tration as the ketones, they present greater dermatitis to the skin, particularly when resins come in direct contact with i t This is possible with such products as epoxy coatings, coal tar cutbacks, and phenolic or phenolic epoxy coatings. When such ma difficulty from a physiological standpoint terials are applied, light protective clothing For example, on Page 245 under "Spray Painting" in the a f Industrial Hy giene, 1944, it is stated that, "The toxicity of the solvents varies from the very toxic benzene to the relatively nontoxic acetone" which is the lowest of the ketones. Also, in Arthur E . Doolittle's The Tcchnohgy of should be used in order to avoid (Greet con tact of the skin with these irritating ma terials. ` The irritation .may be aggravated when combined with the solvents necessary to form the coating. A few simple mtes have been developed which must be reserved in the handling of Solvents and Plasticizers. 1934, it states that. " Ketones arid aldehydes are largely devoid of chronic toxicity . . In the same scr- synthetic resin coatings in enclosed areas. These rules are good practice for the applica tion of any coating in enclosed arcus where ' lion the toxicity of various solvent* is sum inflammable solvents arc a factor. marized in this way: "In summary, chronic toxicity may be expected of benzene and to a lesser extent of other aromatic hydro carbons, of satumted chlorinated hydrocar bons, many nitrogen compounds, glycol de- 1. The. first and most, important point is ventilation. It must be stressed that adequate ventilation wherever advents are found is the key to their safe use. This is true whether they are aliphatic hydrocarbons with low tox rivates, and carhon disulfide. Other solvents, icity or aromatic hydrocarbons with more with, perhaps isolated exceptions, injure dangerous physiological properties. It cannot during industrial-, exposures almost exclu he over-emphasized that adequate ventilation, sively as the result of the amount absorbed from either a fire, explosion or health haz during one day. There may be some ac ard standpoint,, is the key to good coating cumulation in the blood due to slow dhnina- practice wherever these materials are used tion. but there is not the piling up of injury in enclosed areas. 31 1964 Xatiimal Safety Congrcts Ordinarily, no fire hazard will' exist if the solvent vapor concentration in a ir is kept below 1%. This figure is rather empirical however--there is only one solvent in the above list which is below l % by volume. This is turpentine. The amount o f ventila tion required in various sizes of tanks to keep the concentration below th is'lim it is shown in Table V. . 2. Since the solvent vapors are heavier than air, they have a tendency to concen trate in the lower portions of a tank or closed structure. Therefore, the suction blowers should he operated m such a way as to prevent pockets o f solvent vapor being concentrated in the lower portions of enclosed spaces. This can ordinarily be ac complished by sucking the air from the bot tom of the tank so that the circulation is from the top manholes or openings down through the tank and up through the blowers. In this way the solvents are swept down and immediately sucked away from the bot tom portion of the tank, eliminating any pockets of solvent vapor which might be above the explosion limit. 3. Maintain ventilation in the coated tank until the coating is sufficiently dry so that any remaining solvents cannot build up to the explosive limb. See Table IV. 4. The fourth precaution to be observed is the use o f spark proof and explosion proof equipment. Electrical equipment and lights should be explosion proof; tools and shoes shall be spark proof. The use of such equipment has been common practice in the application of synthetic coatings for a num ber of years. 5. Ail smoking, matches, (ire, flanw*. or torches shall be prohibited within 50 feet of the area where coatings are being applied. 6. AH men working in encioxd areas should wear compressed air type masks to supply them with a Sow of clean air at all limes. 7. Where epoxies, Jspoxy coal tar, coal tar or phenolic resins are applied, protective clothing should be wom to eliminate con tact with the liquid coating. If these simple rules are followed during the application of any coating to enclosed spaces, the hazard from fire, inhalation of fumes o r contact with the liquid should be maintained at a level which will provide maximum safety to the individual workman. REFERENCES VINYL CHLORIDE POLYMER AND CO POLYMER PLASTICS Technical Data on Pintle*. Ray. UU P intle R attristi Manufacturai Association. Ina MANUAL OF INDUSTRIAL HTGIENE. ISM Division or Industrial Hygiene National Inatltute of Health U. & Public Health Same MODERN PLASTICS ENCYCLOPEDIA. 190 DANGEROUS PROPERTIES OP TRIAL MATERIALS. 1957 By K. Irving Sax Reiubold Publishing Corporation INDUS THE T ECHNOLOGY OF SOLVENTS AND PLASTICIZERS. 195 By Arthur X. Doolittle Jobs Wiley It Sons, Inc. ACUTE RESPONSE OF GUINEA PIGS AND RATS TO INHALATION OF VAPORS OF ISOPHORONE r Henry F. Smith. Jr., and Jane Seaton ellon Inatltute, Pittsburgh, Pennsylvania Journal of Industrial Hygiene and Toxi cology Volume 9 . No. 10, Paget <77-4X3. December IMO A STUDY OF CONDITIONS FOR THE SAFE APPLICATION OF AKERCOAT COATINGS By E. N. Hieatand and R. E. Hclka Baitelle Memorial Institute September 1. 1953 VENTILATION FOR HEALTH HAZARDS CONTROL IN THE CONSTRUCTION AND REPAIR OF SHIPS By G. S. REICHENBACH Industrial Health Engineer, Bethlehem Steel Company, Sparrows Point, Maryland Shipyard ventilation prior to W orld W ar I t was usually limited to locations where the heat stress upon men due to the high'ambient 32 temperatures and additional radiant heat could interfere with their productivity. During and subsequent to the war, however.