Document 6wNYQZjp30pxYNz23qymmm6po

rder Form 1970 Congress Transactions Stock Vo!. 1-9 18 or 022.22-1 022.22-2 022.22-3 1 2 3 022.22-4 022.22-5 022.22-6 022.22-7 022.22-8 022.22-9 022.22-10 4 5 6 7 8 9 10 022.22-11 022.22-12 022.22-13 022.22-14 022.22-15 022.22-16 022.22-17 022.22-18 022.22-19 02222-20 022.22-21 022.22-22 022.22-23 022.22-24 022.22-25 022.22-26 022.22-27 022.22-28 022.11 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 General Sessions & Index to a!! Volumes $ .95 $ .75 Aerospace; Air Transport .95 .75 Automotive & Machine Shop: Power Press & Forging .95 .75 Cement, Quarry & Mineral Aggregates .55 .50 Chemical; Fertilizer; Research & Development .95 .75 Civic Leadership: Church. Women, Youth, Farm .95 .75 Coal Mining .95 .75 Construction; Public Employee 1.25 1.10 Electronic & Electrical Equipment .55 .50 Food & Beverage; Meat & Leether Industries; Trades & Services .95 .75 Glass & Ceramics; Rubber & Plastics .95 .75 Industrial Subject Sessions: Associations 1.25 1.10 Labor .95 .75 Marine .95 .75 Metals .55 .50 Mining .95 .75 Motor Transportation .95 .75 Occupational Health Nursing: Hospitals .55 .50 Petroleum .95 .75 Public Utilities .95 .75 Pulp & Paper: Printing & Publishing .95 .75 Railroad .55 .50 School 8 College 125 1.10 Traffic; Driver Improvement .95 .75 Wood Products; & Textile 25 .75 Early Morning Sessions .55 .50 Public Safety .95 .75 Home Safety .95 .75 COMPLETE SET OF 28 VOLUMES $14.50 Automatic 20% discount to NSC members; 10% to U. S. Federal Government Agencies. Payment must accompany all orders of $5.00 or less. SHIP TO: Organization,............................................................................................................ ,,..... ...... ..... ...... Address................................... ......................................................... .......... ..... _ City ____________ StateZip Code to Attention of.________________________________ _________________ ________________ BILL TO: Organization__________________________________________________________________ Address CityStateZip Code to Attention of Customer's Purchase Order Number MAIL TO: 47102 NATIONAL SAFETY COUNCIL 425 North Michigan Avenue Chicago, Illinois 60611 FSIR7EB IK U.S.A. 022.22--15 24 f'v r.TV VOLUME 15 OPY V NATIONAL SAFETY CONGRESS TRANSACTIONS METALS NATIONAL SAFETY COUNCIL 425 North Michigan Avenue Chicago, Illinois 606J 7 HAZARDS FROM USE OF RESINOUS BINDERS By HERBERT J. WEBER Director, Safety, Hygiene and Air Pollution Control, American Foundrymen's Society, Des Plaines, XU. The various resinous binders used in foundry processes can be used with complete safety if the necessary precautions are fol lowed. Therefore it is well to consider here the nature and characteristics of these mate rials if a regimen of good safety and hygiene practices is to be adopted. Shell process resins are two stage, where as baked resin core binders are single stage. The two-stage resin is formed by reaction with formaldehyde and an excess of phenol in the presence of an acid catalyst. The product, novolak, is thermoplastic and needs an added catalyst, usually hexamethylenete tramine, to make it thermoset. A single stage, resin is formed by reaction with phenol and an excess of formaldehyde in the presence of an alkaline catalyst The product is thermosetting without the need for an additional catalyst. Shell Process Hot-Coating Resms Shell process hot-coating resins are: 1. Lump novolak, consisting of: phenolformaldehyde polymer, free phenol, formal dehyde (trace), hexamethylenetetramine,1 and release agents.1-1 2. Water-borne resins consisting of: phenol-formaldehyde polymer, free phenol, formaldehyde (trace), ethyl alcohol (four to nine per cent), water (five to 2S per cent), hexamethylenetetramine,1 and release agents.1-2 Shell Process Cold-Coaling Resins Shell process cold-coating resins are: 1. Dry powder containing: ground lump novolak; hexamethylenetetramine, metallic stearates,1 denatured alcohol, and water.1 2. Varnish (alcoholic solution) contain ing: dissolved lump novolak, denatured al cohol (25-35 per cent), hexamethylenetetra mine,1 and release agents.1-1 1. Material added during coating process. 2. Release agents include metallic stearates, high melting point waxes, or silicone poly mer. Dry-Blend Shell Process The dry-blend process consists of mixing the sand grains with the dry powder pre viously described under cold-coating resins. Baked Resin Core Binders. The materials used in baked resin core binders are: 1. Liquid phenolics (single stage): low molecular weight phenol formaldehyde poly mer; free formaldehyde (three-five per cent) ; phenol (trace) ; water, and alkaline catalyst residue. 2. Powdered phenolics (single stage) : higher molecular weight phenol formalde hyde polymer; free formaldehyde; phenol; alkaline catalyst residue. 3. Liquid urea: free formaldehyde; urea (trace) ; water; and catalyst residue (inert). 4. Powdered urea: higher molecular weight urea formaldehyde polymer; free formaldehyde; and free urea. 5. Furfurylated urea formaldehyde resins: furfurylated urea formaldehyde polymer; free furfuryl alcohol; free formaldehyde; urea (trace) ; water; and catalyst residue. Hot Box Resins (Wet Resin Scmd) Hot box resins are; 1. Urea formaldehyde resins containing: furfurylated urea formaldehyde polymers; catalysts such as salts (range: neutral to very add) ; inorganic acids; and organic acids. 2. Modified phenol formaldehyde resins: phenol-formaldehyde polymer; urea formal dehyde polymer; free phenol; free formalde hyde; free urea; and catalyst (salts). Self Curing Resin-Binder Systems Self curing resin-binder systems are: 1. Furan binder containing: furfuryl al cohol formaldehyde polymer; free furfuryl aicohol; free formaldehyde; catalysts resi dues (inert) ; and strong acid catalysts. 2. Modified furan binder containing: same as furan binder; urea formaldehyde furfuryl aicohol polymers. 3 1970 National Safety Congress Toxicity Almost all of the materials and their decomposition products used in these proc esses are toxic, but organic impairment of the body is not likely to occur in the normal operation. The principal effect on man is dermatitis, and even dermatitis does not occur from completely polymerized resins but rather from the excess of free phenol, free formaldehyde, hexamethylenetetramine or alcohol. Formaldehyde has an irritating effect on the eyes, mucous membranes, and skin. It has a pungent and suffocating odor so that a toxic atmosphere is intolerable to man. However, numerous cases of dermatitis have been reported among workers handling it. The maximal allowable concentration in air (MAC) is five parts per million. The MAC for formaldehyde is not a level which if exceeded would result in poisoning; rather, it is a level which if exceeded will result in a nuisance and unpleasant environment. Phenol is a well known poison and is not only a skin irritant hut is a local anesthetic as well, so that hums may not be felt until serious damage has been done. It can lie absorbed through the unbroken skin and appear in the urine, to which it imparts a smoky color. Therefore, besides being capa ble of causing dermatitis, it can do organic damage to the body. The maximal allowable concentration in air is five parts per million. Hexamethylenetetramine is not known to cause organic poisoning. It is, however, a primary skin irritant, which can cause derma titis by direct action on the skin at the site of contact if permitted to act in sufficient concentration and for a long enough time. Furfuryl Alcohol. There have been no reports from industry of health hazards asso ciated with the use of furfuryl alcohol. Daily doses of one gram to dogs were with out effect, and a dose of ISO milligrams administered orally to man caused no dis turbance, However, as with other alcohols it will de-fat the skin and, therefore, con tact with it should he avoided as much as possible. Tt reacts with mineral acids (even dilute) and some strong organic acids with explosive violence. Therefore, great care should be taken to avoid accidental mixing with such acids. Ethyl Aleckof i. practically non-toxic and relatively non-irritating to the skin. How ever, continuous daily contact with it will produce cracking of the skin. Its vapors are highly irritant to the eyes. The MAC is 1,000 parts per million. Methyl Alcohol is sometimes used instead of ethyle alcohol. The former is poisonous. Systemic poisoning can occur from absorp tion through the unbroken skin or from prolonged inhalation. It has a particular effect on the optic nerve. The oxidation and removal of methyl alcohol from the. body requires a greater period of time than for ethyl alcohol. Consequently, there is not only a prolonged effect following a single over exposure to methyl alcohol vapor, but also a tendency for it to accumulate in the body. The systemic effects are due to the con version of methyl alcohol to the more toxic products of oxidation, formaldehyde and formic arid. It should be noted that methyl alcohol can generate vapor concentrations in air greater than twice those of ethyl alcohol. Because of this difference in their rates of evaporation, any given vapor concentration of methyl alcohol will lie generated mure quickly than the same vapor concentration of ethyl alcohol. Hence, because of its toxic nature and greater volatility, methyl alcohol is much more hazardous than ethyl alcohol and, therefore, much more effective, and extensive ventilation is required for methyl alcohol. It is also insidiously toxic, because of its virtual lack of warning properties as contrasted with those of ethyl alcohol. Therefore, in the case of methyl alcohol, ventilation suffi cient to maintain vapor concentrations below 200 parts per million (the maximal allowable concentration) is required; whereas in the case of ethyl, ventilation sufficient to elimi nate a fire hazard is all that is necessary. This will be described later. Obviously, any horseplay with poisonous materials should not be tolerated. Urea decomposes to carbon dioxide and ammonia. Ammonia has adequate warning properties and is intolerable in toxic con centrations. Silicones. The nonhydrolyaable types of silicones used as mold release agents are of a low order of toxicity. From a practical standpoint their hazards are minor. The hydrolyzable types, however, are highly cor rosive and can cause severe burns, hut they do not possess the physical properties re 4 Metals Section quired for shell operations and, therefore, are not likely to be used in the foundry. Carbon Monoxide is given off during pouring operations. The MAC for an eight hour exposure is SO parts per million. The atmospheric concentration of toxic dusts can be averaged for an eight hour day to arrive at the MAC. Thus, peak concentrations far in excess of the MAC can be cancelled out by those concentrations which are far below the MAC and no deleterious effects will result. This is not true for carbon monoxide. For example, an exposure to carbon monoxide of 400 parts per million for one hour is the maximum tolerable without noticeable effects even if the exposure for the rest of the day is zero. Tubich, et ah* found peak breathing zone concentrations of 600-700 parts per million during pouring of shell molds. The lethal effects of even short exposure, to high concentrations of carbon monoxide are well known. Smoke is an atmospheric contaminant re sulting from incomplete combustion, and consisting predominantly of small gas home particles of carbonaceous material. It is given off during baking and pouring of shell molds. Smoke, per se, from shell molds or cores is innocuous, and only in heavy con centrations is it a nuisance. Silica Dust from shell operations has the same effect on the lungs as that from any other foundry operation and is, therefore, capable of producing silicosis under certain conditions. However, in order to produce silicosis there must be sufficient exposure, in terms of time and concentration, to free crystalline silica dust of particle size below five microns. It usually requires two to 20 years (average 10), and then only when dust concentrations greatly exceed the maxi mal allowable, to produce a case of silicosis. The maximal allowable concentrations of silica-bearing dust are determined by the following formula: 250 --------------- = MAC % S,0, + 5 It may be stated that the silicosis risk from the shell process is no different than the risk in conventional foundry operations. 21Ap..M43.A4 . (MAracyhiv19e8s0).of Industrial Health, vol. Prei>ention and Precautions of Dermatitis Predisposing Causes These are the principal factors concerned with predisposition to dermatitis: 1. Nature of the skin. Persons with red hair or fair skin are more susceptible than those with dark complexions. Oily skins withstand solvents better than dry skins. Hairy skins are more apt to develop oil folliculitis than dry skins. 2. Age. Young workers are usually more susceptible than older workers. 3. Sex. There are less cases of dermatitis among women, probably because of cleaner habits and because they ask for treatment for the slightest skin irritation. 4. Season of the year. Dermatitis is more prevalent in warm weather than in cold. 5. Perspiration. One who perspires exces sively is more susceptible to dermatitis than one who does not. 6. Skin diseases. Workers with open skin lesions are more likely to be affected. 7. Allergy. Despite all precautions, derma titis will occur in those persons allergic to resin bonded sand. 8. Uneleanliness. This is probably the most important factor in predisposing to dermatitis. Prevention An unusually extensive dermatitis under conditions of proper cleanliness, subsiding on removal from exposure, and flaring up after return to use of resin, indicates that the person involved has become allergic. Further work with this material by this person is not recommended. The wearing of rubber or latex gloves over a pair of throw-away cotton glove has been found to give effective protection. Protective hand creams are of some bene fit, especially when used as an adjunct to other personal protective equipment. Ade quate facilities for washing, showering, and changing work clothing should he provided. A simple safety rule would be: "Avoid con tact as much as possible by any feasible means and observe strict personal cleanli ness." Treatment Treatment of dermatitis should be given by a physician, or a nurse acting under his orders. Treatment by nonmedical personnel should not be permitted. 5 1970 National Safety Congress Foundry Control Carbon Monoxide. In general, local ex haust systems generally used in mechanized pouring lines will be adequate for controlling carbon monoxide during the pour off. Silica Dust. Silica dust from shell opera tions usually occurs in significant quantities during shake out and dry mixing. However, because of the excellent casting peel from the shell and absence of burn-in, silica dust exposures in the cleaning room are far less than in other types of casting cleaning. Methods for control of foundry dusts are adequately described in the AFS Engineering Manual for Control of In-Plant Environ ment in Foundries. Adds and Acid Salts. Acid and acid salts should be handled in such a way as to avoid spattering or contact witli the body. Depend ing on the type of exposure for operations involving the use of these materials, con sideration should be given to the need for corrosion resistant devices such as hoods, face shields, sleeves, boots, aprons, leggings, spats, and protective creams. Alcohols. The alcohols are high!}' flam mable, and should never be used near open flames or other sources of ignition. Contamers should be periodically inspected for leaks. Clothing accidentally saturated with alcohol should be immediately removed and dried out. In one plant, a man was burned to death when he approached an open flame with alcohol saturated clothing. Explosion Hazards Blending the resins, sand and alcohol in a muller is dangerous unless the vapors rising from the muller are properly diluted with air. A safe dilution is three cfm/lh of sand capacity. This exhaust volume prevents escape of dust and vapor, and keeps the atmosphere inside the mixer below 25 per cent of the DEL (Lower Ex plosive Limit) for air-ethyl alcohol mixtures. These exhaust volumes are confirmed hy using this standard dilution formula. 388 x 100 -(% of EEL) QLEL =------------------------- Mol. Wt. of Liquid Where QLEL = Dilution air required per lb. ethyl alcohol evaporated. 388 -- cu. ft. vapor occupied by rad. wt. in ib. of any vapor. I.EL = 4F.c for ethyl alcohol (eth anol). Mol. Wt. = 46 for ethanol. Substituting: 388 x 100- (25% x 4.3) ------------------------------- = S4J cu. ft. 46 A 1,000 lb sarid batch in which three pounds ethanol are added and evaporated in 10 nun.: Air required for safety: 843 cu. ft. 3 lb. ethanol x-----------------2523 at. ft. lb. Air actually supplied: 3 cu. ft. 10 miss, x IfiOO lb. sand x-----------or lb. sand 30,000 cu. ft.Jib. As far as explosion hazard is concerned, this is enough air even for an open type mixer. It is also enough from a toxicity standpoint, as shown by the formula, for the maximal allowable concentration (MAC) of ethanol is 1,000 parts per million: 388xltOOOflOOxK 6MAC =---------------- ----------------- Mol. Wt. Liquid x MAC Where QMAC = cu. ft. dilution air required per lb. ethanol. K = An experience factor varying from 3 to 10. Substitution (using lowest K factor) : qmac = 338 x 1.000,000 x 3 -------------- ----------- = 25,300 cu. ft.ilb. 46x1000 Assume, as before, three pounds ethanol are evaporated in 10 minutes. Then: 3 lb. ethanol 25300 cu. ft. ---------------- x----------------- = 10 min. lb. 7390 cfm required Air actually supplied: 3 lb. ethanol 30,000 su. ft. ---------------- x---------------------9,000 cfm 10 min. lb. Sometimes methyl alcohol (methanol) is used instead of ethanol. In such event, 9,000 cfm would be sufficient to prevent explosion, but approximately five times more would be required from a toxicity standpoint. In either 6 Metals Section case the amount of dilution air is large, so that the use of a closed top muller exhausted to 25 per cent of the lower explosive limit is indicated. Resin dust is explosive also, as are other finely divided organic or metallic dusts such as hexa, magnesium, and the like. In one case, maintenance men working overhead disturbed a three-year accumulation of resinsand dust on the rafters. The dust cloud was ignited by the gas flame in the shell curing ovens, causing an explosion. The prac tice of blowing down dust with compressed air may create explosive dust clouds. Settled dust should lie removed hy wet or vacuum methods. General The irritating atmospheric contaminants such as phenol, formaldehyde, ammonia and the like, arising from shell operations are a nuisance. The amount and type of exhaust ventilation required for good working con ditions will depend on the local situation. Experience to date shows that hazards in volved in making castings in shell are no more serious than those related to other foundry methods. SAFE USE OF ISOTOPES IN FABRICATION AND ERECTION By KARL A. KRASIN Radiation Officer, Chicago Bridge & Iron Co., Memphis, Tenn. In practically every phase of life we ac cept risks in return for certain gains. It is often said that the risk in dealing with radiation is particularly serious because radiation cannot be seen, felt, or heard by any of our normal senses. This is, perhaps, not a valid statement in comparison with other risks. It may be said that the risk inherent in driving a motorcar is controllable because the driver is at the wheel. But a head-on collison caused by someone driving on the wrong side of the road presents a completely uncontrollable risk situation on the part of innocent vic tims. Apparently, we willingly accept 50.000 traffic deaths per year plus 200,000 crippling accidents for the practical benefits derived from the use of motorcars. We do not abandon cars because of accidents or pro hibit bathing because some people drown. The solution is to teach everyone to swim and promote good driving. As far as radiation is concerned, on the one hand there is no doubt that exposure to certain amounts of it is detrimental to health. It can cause temporary or permanent dam age to the human body and it can be lethal. On the other hand, once we know what its dangers are and how to protect ourselves and others against them, there is much less need to fear it than many other risks we constantly encounter. '> cn can learn to take the necessary pre cautions and understand what you are doing without going too far into the details of radiation physics and mathematics. How ever, some basic knowledge of the nature and behavior of radiation as well as the properties of protective materials, shielding, and operating procedures for radioisotope equipment is essential. Broadly speaking, the term "radiation" means any emission of energy from a point of origin. Heat from the sun. light from a lamp, and radio waves from a transmitter are ail forms of radiation in this general sense. It is only when the radiation is capa ble of penetrating matter and causing ioniza tion along its path that it is called "ionizing radiation." Normally, the number of negatively charged electrons in the outer structure of an atom of matter exactly balances the num ber of positively charged protons in its nucleus. In ionization, sufficient energy is im parted to an atom to upset this electrical equilibrium. The atom loses an electron from its outer "shell" and becomes a positive ion. The displaced electron often transfers to a neighboring atom, making it a negative ion. Thus each ionization event usually results in the formation of an opposite pair of ions. Ionization leaves the affected atoms in an excited state. Chemical and/or physical .7 1970 National Safety Congress changes may then take place as equilibrium is regained. For example, there may be a regrouping of some of the atoms into altered molecular combinations. These changes that take place produce several different forms of ionizing radiation, such as x-rays, gamma rays, alpha and beta particles, and neutrons. For the purpose of this discussion we will concentrate mainly cm gamma radiation, which is produced bv Cobalt 60 and Iridium 192. ' Cobalt 60 ha3 the energy level of approxi mately a million volt x-ray machine, a half life of 554 years, and one curie will produce 14.5 roentgens per hour at a distance of one foot Iridium 192 has the energy level of ap proximately a 400 kilovolt x-ray machine, a half-life of 75 days, and one curie will produce 5.9 roentgens per hour at a distance of one foot. Half-life is defined as the length of time that it takes a radioactive material to lose one-half of its original intensity. A roentgen is the term used for express ing radiation intensity. A milliroentgen has a value of 11 IKK) roentgen. When used with cobalt and iridium it is also used to express the dosage received by the human body. Ionizing radiation is a natural phenemenou as well as something that is produced arti ficially. Man has always lived in its presence. Our natural radiation background results from the following factors: Cosmic radiation @ sea level SO mrem/year Cosmic radiation @ 7.5 miles 500 mrem/year Radionuclides in earth's crust 50 mrem/year Framehouse 50 mrads/year Granite house 300 mrads/year Watches 8 mrem/year Internal body burden 30 mrem/year 188 mrem/year Chest x-rays .5 to 5rem/exposure Dental x-rays .3 to3rem/exposure Routine Gastro-Intestinal x-ray 1r/exposure Average/year 28-300 mrem/year Shoe fitting machines 7,00044,000 mrem/20 sec exposure TV .5 mrem/hr @ 2 inches front receiver There are other isotopes in use. such as Cesium 137 and Thulium 170. however the major portion of industrial work use cobalt and iridium. The variables which influence the affect that radiation has on an individual are: the amount of the body exposed; the part of the body exposed; the time span over which the dose is administered; the age of the indi vidual exposed; and the biological difference among individuals. For instance, the allowa ble dosage for the area of the body exposed varies as follows: Whole body, lens of the eye, gonads, blood forming areas 1 J/-t Rem/Qtr Hands & forearms, feet & ankle 18-34 Rem/Qrt Skin of the whole body 754 Rem/Qtr The Atomic Energy Commission standard operating limit is based on whole body ex posure of no more than 154 rems/qtr year. In addition, the AEC limits the total ex posure received at work at no more than 5R times the number of years since the person was 18 years old (i.e., MPD^S (n-18) where is the age of the individual). No one under 18 years of age is to be employed in radiography work. Thus, for a 35 year old man the permissible accumulative ex posure would be 5 (35-18) or 85 Rem. For a 40 year old man the mpd would be 5(40-18) or 110R, etc. The maximum permissible dose can be used in excess of five rem/year up to 12 rem/year until the man has used up his accumulated permissible dose, then he must drop back to the limit of five rem/year. The cells of the body that are most sensi tive to radiation are: white blood cells; im mature red blood cells; cells lining the gastro-intestinal canal; cells of the reproduc tive organs; skin cells; cells of the blood vessels; and cells of the tissue, bone, muscle and nerves. Persons exposed to radiation cannot spread radiation damage to others. The only haz ard can be caused by contamination; that is, by dust or loose particles, or breathing, swal lowing, or breaks in the skin. Overexposure to radiation can cause physical damage such as: injuries to super ficial skin tissues in the form of burns and ulcerating non-healing wounds; malignant tumors; general effects on the body, par ticularly on the blood and blood-forming organs in the form of anemia and leukemia; other effects such as loss of hair, cataracts, impaired fertility, and reduction of life span. Overexposure can also cause genetic or hereditary effects on offspring which may 8 Metals Section not show for several generations. Some damage will be temporary and some will be permanent, and as already mentioned, a large enough dose will be lethal. The hazard is increased as more of the body is included in radiation exposure. It is greatest when a large part or the whole body is irradiated. If a finger or hand receives 400-500 r of x- or gamma radiation in one day, it will certainly result in local reaction but in very little systemic reaction. But if the whole body is exposed to such a dose, the results would be fatal. Since in many cases it is difficult to determine the width of the radiation beam or the amount of scatter generated, it should always be as sumed that exposure to radiation is a "whole body" exposure. The tables below show some of the effects that can be expected for various radiation doses. Symptoms of Exposure to Whole-Body Penetrating Radiation Exposure (REM) Probable Biological Effects 0-25 25400 No significant effect nor delayed reaction, Exposed individual may have head ache, dizziness, odd taste in mouth, or smell in nostrils. May have slight blood change. Usually able to return to work without any de layed effects. 100-200 'Results in nausea, fatigue, vomit ing, Delayed effects may shorten life expectancy as much as one per cent. 200-300 Results in nausea, vomiting in first 24 hours. Two weeks later, loss of hair, loss of appetite, genera! weak ness and fever, sore throat. Re covery in about three months 300-600 Nausea, vomiting and diarrhea within hours of exposure. (400 REM is fatal to 50 per cent.) 600 or more Symptoms as above, followed by possible eventual death of all individuals exposed. When you study medical and industrial regulations, you may well ask why more emphasis is placed on safety precautions in the handling of radioisotopes in industry than there appears to he for the use of x-ray equipment. Industrial applications in general present somewhat greater hazards than medical ap plications for the following reasons: 1. Workloads can be very much higher; automatic installations often operate con tinuously. 2. Industrial workers are usually not fa miliar with the biological effects of radiation and they are, therefore, less likely to be safety conscious in this respect. 3. There are greater differences in technic, since the radiographic objects may vary from a small component to a huge tank or casting. 4. Medical radiography is largely confined to specially designed rooms with radiog raphers shielded from radiation by a control cubicle. In industry, on the other hand, the radiation source is often taken to the '`ves sel" in open areas without any fixed skidd ing to protect the operator or other per sonnel. Secondly, there are additional hazards in radiography with radioisotopes: a radioiso tope is radiating all the time, while an x-ray unit gives off radiation for a pre determined exposure time only. X-ray appa ratus "fails sate"; radioisotope source con tainers generally do not On the other hand, the advantages of gamma ray projectors, such as portability, reliability, and ease of operation, ansi independence of power and water supply should always be considered. They outweigh by for the .slight extra risks that may be involved by using properly trained personnel. _ It's obvious that the primary beam of cither an x-ray or an isotope unit will be of higher intensity and hence more danger ous than scatter or background radiation. However, since scatter radiation is far more difficult to measure, it can present a more difficult shielding or protection problem. By definition, scatter radiation is radiation of varying intensity which bounces off the weldment, walls, or other objects in a ran dom manner. Scatter radiation can read: places where direct radiation does not--be hind the thick wall, for example. The prob lem of scatter radiation is complex and can be calculated only with difficulty under the various conditions encountered in radiogra phy. Even though scatter radiation may hr 9 1970 National Safety Congress of much lower intensity than the primary beam, its effect can be just, as hazardous over a long period of time and should be accurately measured with a calibrated survey meter in good working order. Exposure to radiation can be limited in three ways: time: distance; and shielding. If you work near radiation, the simplest way to limit your exposure is to stay in the vicinity as short a time as possible. If there's a tune limit on your job, observe it. A second method is to maintain a safe distance between you and the source of radi ation. What distance is safe? In general, the effect of radiation falls off sharply as you increase your distance from the source. Double the distance and your exposure is cut to one quarter. As an example of the inverse square law, take an x-ray beam directed against a steel tank. At a distance of four feet, the radiation intensity will be 1/ 16th what it is at the focus point of the beam on the tank. At right feet, the inten sity will be J4 what it was at four feet, or 1/64 that at the focus point If the radiation at the right-foot distance is less than the maximum permissible exposure as estab lished by local, state, or federal regulations, then any other print eight feet away from the source of the radiation should be a safe area. The third method is shielding by placing some material between tire source of radia tion and area to be controlled. The amount of radiation that can get through any mate rial depends upon the nature of the material and its atomic structure, and its thickness. The absorption of radiation in or transmis sion by the ionizing radiation is exponential in character, and this value can conveniently he expressed by means of a term called "half-value" layer, or half-value thickness. The half-value layer is the thickness of material required to reduce the radiation intensity to one-half its original intensity. Thus, it can he shown that if you place .49 inches of lead into a radiation beam from a cobalt 60 source, only half the radiation will get through. The radiation from an iridium 192 beam will be reduced to half its intensity by .19 inches of lead. Similarly, the thickness of material which will reduce the intensity of the radiation to one-tenth is called the tenth value layer. Every method of effectively combatting radiation depends on first bring able to measure the level that must be protected against. This leads to a need for surveillance and constant monitoring of potentially haz ardous environments. The following rules are suggested for individuals engaged in either radioisotopic or x-ray inspection of weldments: 1. Respect radiation as one would an elec tric fence--keep as far away as possible. 2. Exposure times should be known and carefully controlled. 3. AH employees entering radiation areas should have a film badge, a pocket dosimeter, and a survey meter to assess radiation levels. 4. Establish safety measures--and rigidly enforce them. How are radiation hazards legislated? Since 1954, the Atomic Energy Commission has been granting licenses to industry for the use of nuclear materials. Since those forms of nuclear energy which are trader AEC license are only part of the radioactive source*, which can be harmful, many states have passed legislation controlling radiation from x-rays, accelerators, radium, etc. Al most half of the states require the registra tion of radiation sources. Seven states have comprehensive radiation protection codes. The Atomic Energy Commission recom mends the creation of a "supervised" area for nh radiography or NDT inspection projects involving x-ray or isotopic equip ment. This supervised zone is an area within which the exposure that one can receive exceeds 0.5 rem per year, which is one-tenth the total permissible exposure for operators. The zone should be marked off by walls, shielding, or obstacles, or by signs placed three feet above floor level -- dancer -- radiation -- every 15 feet.. At the time of the first eiqs.sisre, the zone should be calculated and then com pletely checked out. It can be done as fol lows: calculate the restricted 2mr/hr limit, and locate the ropes, signs, and flashing lights. Then during the. exposure an assistant is posted at the radiation equipment to cut off the current or withdraw the isotopic source on signal, while a complete survey is made of the periphery of the radiation zone with an appropriate radiation survey meter. Any point on the edge of the zone should not indicate a radiation exposure of more 10 Metals Section than two rar in any one hour, or if the individual's continuous presence in the area could result in his receiving a dose in excess of lOQmr in any consecutive days. In the case of the intermittent use of the radiation-producing equipment, such as onand-off radiography of welds, calculations should be made as to the percentage of time radiation is being produced. Thus, if the equipment is in use 50 per cent of the time, the exposure permissible could be doubled, etc. For maximum protection, it would be a good idea to check the limits of the radiation zone daily at the time of the first exposure. Currently, federal licenses are required for the use of one to 250 microcuries of radioactive isotopes--the number of micro curies depending upon the specific isotope. Below these individuals level, no license is required. There are 22 so-called "agreement" states which have licensing agreements with the AEC and which provide control over radia tion-producing sources within their state: Alabama, Arizona, Arkansas, California. Colorado, Florida. Georgia, Idaho, Kansas, Kentucky, Louisiana, Mississippi, Nebraska, New Hampshire, New York. North Caro lina, North Dakota, Oregon. South Carolina. Tennessee, Texas, and Washington. A typical section of an agreement state's regulations for control of radiation includes a specific reference on radiation survey in struments: "The licensee or registrant shall maintain, sufficient calibrated and operable radiation survey instruments to make physi cal radiation surveys as required. Each radi ation survey instrument shall be calibrated at intervals not to exceed three (3) months and after each instrument servicing, and a record maintained of dates of calibrations. Instrumentation required by this section shall have a range such that two milliroentstens per hour through one roentgen per hour can be measured." Recalibration of the survey instruments is relatively simple and is most often performed by field service representa tives of the instrument's manufacturer. Some instruments are sent to the National Bureau of Standards. Although there are a variety of scanning and monitoring devices which can be easily used by the person who works with radia tion. it's recommended that a trained health physicist be used if necessary to insure the use of suitable instruments in the proper way, to interpret the readings obtained, and to make necessary recommendations for re ducing hazards. The main reason it takes a somewhat skilled person to accurately measure radia tion is that radiation hazards arise from a wide variety of sources and the monitoring methods must vary accordingly. This is particularly true in situations involving a mixture of two or more types of radiation. Organizations or individuals who utilize radioisotopes must comply with AEC regu lations Title 10 Part 34. which requires the use of a radiation survey' meter capable of reading 2mr/hr. to 1 r/hr.; a pocket dosim eter or pocket chamber (0-200mr) ; a film badge; and a Geiger counter instrument capable of measuring 0.005 microcuries of removable contamination from the source container. AH industries, whether in an agreement state or not, are controlled by these regulations. Other radiation sources are not controlled by individual state regula tions. The above listed instrumentation is also appropriate a basic survey protection, equipment for most other radiation-produc ing equipment, x-ray units, electron beam welders, etc. Over the past 40 years, manufacturers of surveying and measuring equipment have introduced many devices designed to better protect the worker who must be near radia tion. These devices include the pocket dosim eter, the "beeper" or "chipper" worn on belt or in the pocket, the Geiger counter (the Geiger-Mudler tube) , the ion chamber, and scintillation counters. Usually it takes a combination of these instruments to effec tively warn of the dangerous levels of radia tion. Basically, this is true because radiation consists of different energies of rays or particles and many different intensity levels --not all measurable with one instrument. The design theory behind all radiation exposure measuring devices is that the de tector should respond to radiation in the same manner as human tissue would--where the main effects of radiation occur. Modem radiographic source-manipulating devices or "projectors" are so designed that it is no longer necessary to handle unshielded radioactive sources directly. When not in use, the source is normally contained in an adequately shielded storage safe or storage n 1970 National Safety Congress container and is moved out of its safe by means of remote control for radiographic exposures. In one design of a safe remote handling arrangement, the radioactive source itself is sealed in a stainless steel capsule securely fastened to the end of a steel cable. By means of a remote control, the cable propels the source from the safe to the end or snout of a source guide tube which has been positioned for radiography on a tripod stand or other holder. At the end of each exposure, the cable, cranked in the opposite direction, pulls the source lack into the safe. Signal lights or an odometer indicate wheth er the source is in the safe, in the snout, or in between. In some models the indicating light system can he used to operate addi tional audible and visual warning systems or other safety devices such as door locks. The AEC regulations require that source holders be equipped with a lock to prevent operation or tampering by unauthorized personnel. The guide tube can be connected to a beam-shaping device or collimator so that the radiation beam may he confined to the shape of a cone by means of a lead shield as opposed to an unshielded or free source which emits radiation in all directions A collimator permits the use of the beam for radiography while reducing the protection required in other directions. The collimator may be mounted on a portable adjustable stand so that it can he positioned for ra diography. By means of interchanging lead shields in the collimator, a variety of beam angles and shapes can he obtained. Confining the radiation beam to the necessary minimum not only blocks the unwanted primary radia tion but also greatly reduce , scattered ra diation from surrounding walls, floors, and possibly other objects. This reduces the radiation area or shielding material required and therefore helps to minimize work inter ruptions for plant employees not directly concerned with the radiographic procedure. Since collimated beams also reduce the amount of scattered radiation reaching the film, they will increase radiographic quality by increasing contrast and, therefore, in crease visibility of detail. In some cases, the source is shielded by the object to he radiographed such as a pressure vessel or tube radiographed from the inside out. but where this is not the case, collimators should he used as much as possible. Control cable operated units also greatly facilitate the safe replacing of spent sources by means of connecting the source guide tube to a source changer. A source changer is a shielded storage container into which a spent source can be deposited and from which a new source can be extracted in very much the same way a radiographic exposure is made. The radiographic set-up and positioning of the source should be completed before the source is moved from the storage con tainer at the end of each exposure. Even though indicators and warning lights may show that the source is in the "safe" or "stored" position, the best way to make ab solutely sure of this is to use a radiation survey meter. Since there is always some slight leakage from loaded storage contain ers, the source must he in the container when the highest radiation intensity is at the container. In operating gamma radiation projectors, care must be used in directing the beam away from areas where other people are working. The area around the source should be surveyed with a radiation meter for pri mary, scattered and transmitted radiation and the area should be posted with radiation signs in accordance with current AEC or other applicable regulations. I" ideographic rooms or areas must he pro vided where radiography may he safely performed. For in-plant radiography, the most suitable facility is, of course, a special room which can be permanently protected and to which access can he controlled. Wall thickness and layout of the room should be such that the radiation outside the room is reduced to levels which comply with current AEC and other applicable regulations. A radiation warning sign should be posted at the entrance to the room. Tn planning a radiographic room, advan tage should be taken of the section of the plant that can best be used from the radia tion safety point of view. While it would he desirable to have wall thicknesses such that the radiation beam can be pointed in any direction, this may not be possible nor is it necessary in many cases. Proper plan ning of the location of the radiographic setup within the room will help to keep radiation levels in occupied areas outside the 12 Metals Section room to a minimum. The center of a room may not always be the best location for a setup; better protection can sometimes he obtained by placing it in a comer of the room or next to a wall bordering an un occupied area. Careful attention should be given to the possibility of secondary radiation from the roof or other objects over the room or site, which may reach individuals outside the radiographic area. Though the intensity of scattered radiation may not exceed a frac tion of one per cent to a few per cent of that of the primary radiation, the exact amount is difficult to predetermine since it will depend upon several factors. The only reliable way to be certain that a potential hazard from scattered radiation does or does not exist is to make measurements with a radiation survey meter. Where radiography must be performed in an open plant area, the area must be roped off and posted with warning signs or other wise barricaded for the appropriate radiation levels in accordance with current AEC or other applicable regulations to prevent un authorized personnel from entering the area. Sometimes a good solution is to perform radiography at night or other times when few or no other persons are around in that part of the plant Similar measures must be taken m field applications such as the radiog raphy of welds on pipelines, pressure tanks, refineries, and other construction projects. Considering the time required for radiation surveys, roping and posting the perimeters of: radiation areas, it would seem that a permanent or even semi-permanent radio graphic room is probably the more econom ical and most certainly the safest solution in spite of the initial expense. Any radiographic room or site to which access is restricted should be under direct surveillance by the person in charge to make certain that unauthorized workers, bystand ers, or curiosity-seekers do not enter. The radiographer in charge must he thoroughly trained in radiation safety and he is respon sible for maintaining adequate precautionary measures to prevent unnecessary exposures to anyone. The site should also be equipped with a control device to cause the level of radiation to be reduced to a safe level, or sound an alarm (either visible or audible) so that the individual and the radiographer in charge are made aware of the entry. To keep radiation levels outside the radio graphic field in open areas to a minimum, good use can sometimes be made of tempo rary shielding material such as concrete or cement blocks or specially designed mobile shields. A reliable and suitable radiation survey meter should always be available at each installation or site. Radiation surveys at the site for the purpose of establishing working times within the area should be a routine procedure. A survey also gives the radiog rapher a quick means of measuring dose rates around the site to determine where restrictive barriers should be placed. Although the allowable radiation leakages from storage containers is low, it still is too high for anyone to be in close proximity to the container for an extended period of time. Storage containers, when not in use, must therefore be stored in locations inac cessible to unauthorized personnel. All such storage facilities, including moveable con tainers, must be posted with the appropriate warning signs and equipped with locks. Moreover, storage facilities must, of course, be such that no one outside the storage room could receive more than the allowable exposure. Transportation of radioactive sources must be done in accordance with the regulations pertaining to the carrier and the method of transportation involved. Sources carried by rail or commercial motor vehicles are subject to the Interstate Commerce Commission (ICC) regulations. These regulations are enforced by the Bureau of Explosives and the Association ol American Railroads. Ship ment by air is controlled by Civil Air Regu lations, whereas, transportation by water comes under the jurisdiction of the United States Coast Guard. The United States Post Office Department has regulations covering shipment of radioactive materials by the postal services. The latest information con cerning transportation of sources should be obtained from the appropriate agency for the carriers involved. Over-exposures to radioactive materials do occur, and each such incident is investi gated, when the personnel acknowledge the incident. Periodically some of the incidents are reported to holders of isotope licenses in order to alert and explain the necessity of using the proper care in following pro cedures when using these materials. These 13 1970 National Safety Congress reports show that in almost ail cases of overexposures the radiographer did not use a survey meter, the meter was not in op erable condition, or it was not used properly. Even though the exposure device may be equipped with lights or warning devices, the only sate way to make sure the source is safely stored is to use the survey meter. In order to determine whether your survey meter i?. working properly, many license holders mark a spot on the camera and check the meter at the same location each lime the meter is to be used. This serves two purposes, (1) it checks the meter for accuracy and (2) proves the source is in the camera. However, in checking the ac curacy of the meter the decay curve for the isotope must be taken into consideration. This operation does not substitute for hav ing the meter calibrated every three months ns required by the AEC or state license. 14 Metals Section EXPLOSION POTENTIAL OF FINES GENERATED IN GRINDING, POLISHING, AND CUTTING OF ALUMINUM ALLOYS By F. H. ILLIG Manager of Safety, Aluminum Company of America, Pittsburgh, Pa. The explosion potential of aluminum pow der is widely recognized, but the fact that aluminum fines produced during normal op erating procedures may well have, to some degree, the same explosion possibilities is not well appreciated. Because most fabricators do not know of this problem and its inherent danger, we felt it necessary to make this presentation. We will describe for you a few of the more serious accidents that have oc curred in this field over the last several dec ades. Following these accident descriptions, we will outline in some detail the type of dust collecting equipment that can be used in these processes and the safety precautions required in their use. A very serious explosion of this kind oc curred in the mid KMO's at Bridgeport, Con necticut. The explosion took place in the finishing room of an aluminum foundry where they were snag grinding castings. Six people were fatally injured. A small fire was observed in the grinding hood and, as an employee was going to apply G1 powder, it is believed that a spark from the fire was carried into the exhaust system, which set off a minor explosion when it reached an explosive mixture of dust and air. This first explosion triggered a second major blast that destroyed the equipment and caused the multiple deaths. Another major explosion occurred in W64 in the trim room of a sand foundry. It was somewhat similar to the first one described. In this instance, two men were working ad jacent to each other on swing frame abrasive cut off saws. The saws were being used to trim oft" exec s metal such as headers and risers from sand castings. There were floor level collecting hoods positioned to collect the aluminum fines from the saws and a swung frame abrasive grinder. These collector hoods were connected to a 20-inch duct which led to a cyclone-type collector bin on the roof of the building. This was a dry collection system. The two swing frame saw operators were both experienced men. At the time of the explosion, one operator was cutting a section with a steel chill tube in it from a large crank case casting- In doing so, he cut into the steel chill tube and threw sparks into the collecting hood. These sparks set off a minor explosion which in turn, stirred up dust in the system which triggered a major explo sion. This explosion blew back through the system and burned both operators so seri ously that they later died. The explosion destroyed the collecting system, and blew out windows in the trim room. The saw operators had been warned re peatedly not to ait into steel chill rods. Evi dence proved that this operator had been doing so for over two minutes, when the explosion took place. A third incident occurred just three years ago when a dust collecting unit exploded and burned two men so seriously that they had to be hospitalized. This unit was bring used to collect dust from hoods enclosing four wire brush wheels used to remove oxidation from aluminum tape This dust was com posed of aluminum, aluminum oxide, and steel. The dust was conducted from the hoods into a collecting drum having a cover mounted filter and exhaust fan assembly. Air was drawn from the drum through the filter bag, into a two stage fan combination, and exhausted around the motors to the atmos phere. The drum was approximately !& full of water with a layer of dust on top of it. This explosion was not a dust explosionKather, it resulted from an accumulation of hydrogen, generated by the reaction of alu minum fines and water. The motors and switches were not explosion proof. A fourth and extremely serious explosion of aluminum fines occurred in Cleveland just a few years ago. At this comparatively small foundry, the castings were smoothed up in the finishing room, using belt grinders and wheels. Over the years, a considerable amount of aluminum fines had accumulated on the IS 1970 National Safety Congress building steel, window ledges, and on top of equipment. A serious fire broke out and all plant and office personnel were safely evac uated. Firemen moved into the building with hose equipment. The high pressure hose kicked a cloud of aluminum dust into the air and caused an explosion which in turn trig gered several more explosions. These explo sions destroyed the building and caused the death of five firemen. We would like to em phasise at this point that if the dust and fines can be carried to adjacent building structures by air currents, then you well may have the potential for an explosion. Now, let us discuss how we can minimize the possibility of accidents such as we have just described. Much of the information that we will pass on is available in N.F.P.A. Code No. 65, "Dust Explosion Prevention Aluminum Processing 1970," and we should have a N.S.C. data sheet on this subject in the near future. Machines which produce aluminum fines with explosive potential shall be provided with suitable hoods or enclosures connected to a collector with ducts that lave sufficient suction to collect and transport all dust. The hoods and enclosures shall be maintained so that the fine particles will either fall or be projected into them in the direction of the air flow. Individual dust collection units shall be located as dose as possible to the dust source so that the connecting duct will 1m short. If more than one machine is to he served by a single dust collector, the ma chines should be arranged close to the col lector so that all connecting ducts shall be as short and straight as possible. Short, straight ducts reduce tire explosion hazard and accumulations of tallow, wax, grease, or oil with metallic fines can be readily seen on inspection and removed. Ducts shall be of metal construction and fabricated with a smooth interior and with internal lap joints pointing in the direction of air travel and without unused capped side outlets or other dead end spaces in which dust could accu mulate. The dust systems, collectors, and machines shall be grounded electrically in accordance with recommendations of the N.F.P.A. Code No. 77M, "Static Electricity." The system shall be installed in accordance with N.F.P.A. Code No. 91, "Blower and Exhaust Systems for Dust Stock and Vapor Removal," Wet Type Dust Collectors. Wet type dust collectors convert dust into sludge. This sludge must be covered by a blanket of water since wet aluminum fines are highly com bustible, particularly in the presence of hy drogen. Hydrogen has a very low explosive limit and requires a very low energy level to initiate an explosion. A minor hydrogen ex plosion could serve as a fuse or primer for a major sludge explosion. The dust collector shall be arranged to prevent contact of dusts in the dry state with high speed moving parts. The exhaust fan for drawing the dust-laden air into the col lector shall always be located on the clean air side of the collector. Sludge shall be removed from the collector at least daily and more often if conditions warrant Sludge shall not be allowed to ac cumulate to a depth of more than 2{4 inches, and sludge must always be covered with water. Wet collectors shall have positive ventila tion of the sump at ail times, and the scrub ber exhaust fan control must be interlocked so that: 1. The exhaust fan will operate for at least three minutes to purge the system, of hydrogen before the process can be started. 2. The process cannot operate unless the exhaust is operating, 3. The process cannot operate unless there is sufficient water in the scrubber. 4. The process cannot operate it there is a failure of water pressure servicing the -.crabber. 5. The scrubber exhaust fan shall continue to operate for a minimum of two hours after the process is shut down. Dry Tvi Dust Collectors. Air duet veloci ties shall not be less than 3,500 feet per minute and shall be monitored at regular intervals, to make certain they are not drop ping below safe levels. Dry dust concentra tions must be less than five ounces per thou sand cubic feet of air. Where dry dust collection equipment is used, the collection point shall he located outside the building. Special care shall be exercised to guaran tee the internal cleanliness of dry systems at all times, to avoid accumulations of ma terial at locations other than in the collectors themselves, and to prevent the creation of an explosive dust cloud under any rirenm- 16 Metals Section stances. Dust shall be removed from dry collectors at least daily or more often, if conditions warrant. Dry dust collectors and other equipment where dust explosion hazards exist should be provided with adequate explosion vents. The guide for explosion venting, N.F.P.A. Code No. 68, contains information on methods of providing adequate explosion vents. Extreme care shall be taken to prevent the introduction of water either directly or by condensation into a dry collector system since hydrogen is generated when aluminum fines are in contact with water. Sludge and Dust Removal and Disposal. Sludge shall be placed in non-combustible containers, preferably of not over 50 pounds capacity each, and removed from the build ing promptly. Dust shall be removed from the collectors at least daily, or more often if conditions warrant Sludge and dust disposal shall be by one of the following methods: 1. It can be mixed with a large volume of sand and discarded in a dump. 2 It can be dumped in an open pit. The pit shall be fenced or guarded from public access. 3. It can be spread over the ground in an isolated area where it will oxidize. An area of this sort shall be fenced or guarded from public access. Equipment Selection. Electrical equipment within five feet of the dust producing source which in normal operation can be expected to produce an occasional spark shall be ap proved for Class II, Group E locations un der Article 500 of the National Electrical N.F.P.A. Code No. 70. Examples of such equipment are pushbuttons and toggle switches. All other electrical equipment shall he enclosed in dust-resistant enclosures of NEMA 5 or NEMA 12 construction. All motors and pulleys should be equipped with conductive drive belts and the belts should be tested at least once each six months for loss of conductivity. Elimination of Ignition Sources. No open flames or lights, smoking, electric, or gas cutting or welding equipment shall be per mitted in the section of the building where aluminum dust is produced or handled. If it becomes absolutely necessary to use cutting or welding equipment for making repairs, all machinery in the section where the work is to be done shall be shut down, the ducts cleaned, the collectors emptied and cleaned, and all accumulations of aluminum dust shall be thoroughly cleaned up and removed from the area. The area must also be free of sol vents and solvent vapors. A well-administered permit system for welding and cutting is strongly recommended. Grinding wheels should not he dressed where the hot material thrown off by the dressing tool, can ignite deposits of aluminum dust in the hood, ductwork, or around the framework of the equipment If it is not feasible to remove wheels to a safer location for dressing, hoods should be thoroughly cleaned or removed entirely before wheel dressing operations are started. All deposits of dust on and around the wheel should be removed before, during, and after dressing. Housekeeping. Good housekeeping shall be practiced in the entire work area. The floors, exposed structural members, piping, conduit, and ducts shall be kept free of dust Duct work shall be inspected on the inside for accumulations of dust as frequently as ex ploratory experience dictates and cleaned thoroughly if necessary. Geaning shall be done with a soft brush or squeegee, non-sparking scoop, and con tainers. Do not use a brush with plastic bristles. Foreign objects, especially combus tibles such as paper, cigarette butts, etc., shall never be introduced into a dry collector system. Solvents shall not be stored near areas where aluminum dusts or fines may be gen erated. Tests by the Underwriters' Lal>ora teries indicate that aluminum dust in contact witli methyl chloride, carbon tetrachloride, or carbon tetrachloride-chloroform is capable of explosion, and the methyl chloride may form a spontaneously combustible aluminum methyl compound. Fire Extinguishing Equipment. Only dry powder shall be used on fires in which there are aluminum fines or aluminum dust. The use of fine dry sand (preferably that screened through a 20-mesh sieve) or approved pow der is an effective method of isolating in cipient fires of aluminum fines. An ample supply of sand or powder should be kept in covered bins or covered receptacles. These receptacles should be placed in operating 57 1970 National Safety Congress areas where they can be easily readied at all times. A long-handled shovel shall be provided at each receptacle to afford a ready means of laying the sand or powder around the perimeter of the fire. The implements shall be made of aluminum or other nonferrous material. Nearly all vaporizing liquid fire-fighting agents react violently with burning alu minum, and they shall not be used where aluminum dust fires may occur. Water streams or liquid sprays of various kinds that vaporize quidcly are highly dan gerous ; they cause dust to he thrown into the air, and the ignited particles instantly cause a violent explosion. For the same rea son, any mechanical agitation or disturbance of the burning dust must be avoided. For these reasons, control of the activities of an outside fire-fighting department is impor tant since this hazard in fighting aluminum dust fires may not be recognized. Recommended Clothing. Outer clothing of a porous or loose weave shall not be worn since dust will easily accumulate on and even in this type of cloth. The material should be closely woven, trousers shall not have cuffs, and aprons or jackets shall not have pockets. Qothing with frayed edges should be avoided. Chemically treated clothing that will not sup port combustion is recommended. This type of clothing may require retreatment after a number of washings. Further Precautions. Finally, if you believe that your manufacturing procedure is devel oping fines with explosion potential, you will want to make a positive determination of the degree of your hazard. We suggest that you contact the U. S. Bureau of Mines and, although they do not do this type of testing anymore, they have had a broad experience in "the past. They can tell your laboratory personnel how to run such an analysis or refer you to a facility that can make the proper tests. An important factor that must not be for gotten is that a change in the mechanics of your processes, such as speeds, fineness of the abrasive medium, lubricating material, or a change in the type of alloy being processed may well create a sufficient difference in the particle size of the fines to develop a hazard potential that did not previously exist. Any change of the type described or change that could result in fines of a smaller size being generated should precipitate immediate re analysis of the fines. 18 OFFICERS OF THE METALS SECTION NATIONAL SAFETY COUNCIL 1970-71 General Chairman--Steve Collins, Gen. Supervisor Safety, Training & Comm. Rel., Mid west Steel Div., National Steel Carp., Portage, Ind. First Vice Chairman--J. E. Sfbowls, Safety Manager, Caterpillar Tractor Co., Peoria, III. Second Vice Chairman--J. B. Anderson, Sen. Safety Engr., Republic Steel G:>rp., Cleve land, Ohio Third T'ice Chairman--G. H. Reilly, Safety Engr. Admin., United States Steel Corp,,, Pitts burgh, Pa. Secretary--B. Brown, Supvr. of Safety, Youngstown Sheet & Tube Co., East Chicago, Ind. Staff Representative--E. E. Koch, National Safety Council, 425 N. Michigan Ave, Chicago, 111. 60611 Congress Program Committee--R. F. Schroeher (Chairman), Mgr., Indus. Prog., Joseph T. Ryerson & Son. Chicago, 111.; William M. Smith, Mgr., Health Services, National Steel Corp., Weirton, W. Va.; H. W. Gilberg, Works Safety Admin., Jones & Laughlin Steel Corp,, Aliquippa, Pa.; E. V. Grotto, Division Manager, Safety & Prct. Service. Kaiser Aluminum & Chemical Corp., Oakland, Calif. Newsletter Editor--Wm. Faison, Gen, Supvr. Safety, United States Steel Corp., Chicago, 111. Ofi-the-jssb Committee--T,, T. Finder (Chairman), Safety Dir., Keimecott Copper Corp,, Utah Copper Div., Salt Lake City, Utah; D. E. Gleohgrn, Safety Mgr., Motor Wheel Corp., Lansing, Mich.; A. H. Goelsehleuchter. Wks. Saf. & Prot Serv. Supvr., Kaiser Alum. & Chemical Corp., Ravenswood, W. Va. Special Activity Sr Publicity Committee--H. W. Gilbekg (Chairman), Works Safety Ad min,, Jones & Laughlin Steel Corp., Aliquippa, Penn.; R. R. Hoffman, Mgr. of Safety, 'Caterpillar Tractor Co., Peoria, III. Foundry Industry Committee--W. H. Decker (Chairman), Safety Dir., Central Foundry ! Div., Danville Plant, General Motors Corp,, Danville, III.; Thomas L. Hewitt, Vice President Indust. Rel. and Pers, Vulcan Mold & Iron Co., Latrobe, Penn,; Gary Robin son, Safety Dir., Pontiac Motor Div., Pontiac, Mich.; Frank W. Nunan, Safety Supvr., Caterpillar Tractor Co., Mapleton, 111,; John P. Hopkins, Dir. of Pers, Admin., Lakey Foundry Corp., Muskegan, Mich.; D. E. Gleghorn, Safety Mgr., Motor Wheel Corp., Lansing, Mich. Steel Service Center Committee--P. M. Walter (Chairman), Vice President National Steel Service Center, Inc., Evanston, 111.; Edward R. Patterson, President, Patterson Steel Co., Tulsa, Okla.; Marvin P. Schramm, Vice President A. M, Castle & Co., Franklin Park, III.; A. D. Reese, II, Manager of Labor Rel., United States Steel Supply Div., Chicago, 111. Industrial Hygiene Committee--John A. Janoos (Chairman), Dir.-Indust. Hith. & Saf. Serv., American Iron and Steel Institute, Washington, D. C.; D. L. Webster, Industrial Health Eng., Bethlehem Steel Corp., Bethlehem, Penn; William M. Smith. Mgr. Health Services, National Steel Corp., Weirton, W. Va.; W. E. Sebesta, Chief Industrial Hygienist, Republic Steel Corp, Research Center, Independence, Ohio 19 Technical Publications Committee--R. D. Tranter (Chairman), Steel Group Safety Engr., Middletown, Ohio; Howard L. Seimetz, Supervisor of Safety, Central Alloy District, Republic Steel Corp., Canton, Ohio; John A. Janous, Dir.-lndust. Hlth. & Saf. Serv., American Iron & Steel Institute, Washington, D. C.; Alex Guzowsky, Safety Engineer, C. F. & I. Steel Corp., Pueblo, Colo.; H. A. Polk, Supt. Safety, Kaiser Steel Corp., Fon tana, Cal.; G. F. Grace, Sales Manager, Columbus McKinnon Chain Corp., Tonawanda, N. Y.; Richard L. Keeling, Safety Eng., Bethlehem Steel Corp, Bethlehem, Penn. Research and Advisory Committee--`J. Patlyek (Chariman), Mgr. Indust. Rel, East Chi cago Works, Blaw-Kncx Company, East Chicago, Ind.; *C. P. Vorhes, Mgr. of Safety, Jones & Laughlin Steel Corp, Pittsburgh, Penn.: *B. D. Kent, Safety & Security Supvr, Aluminum Company of America, Davenport, Iowa; *W. T. McLean, Gen. Safety Engr, Gary Works, United States Steel Corp, Gary, Ind.; *G. Lundie, Director, Safety & Plant Prot, Inland Steel Co, East Chicago, Ind.; `Charles E. Wilson, Asst, to Mgr. of Safety and Wkmn's. Comp, Bethlehem Steel Corp, Bethlehem, Penn.; *J. W. Tysse, Manager of Safety, Republic Steel Corp, Cleveland, Ohio; `James G. Cullen, Div. Safety Eng., Ford Motor Co, Engine & Foundry Div, Dearborn, Mich.; *G. J. Eicenbrod, Safety Dir., McLouth Steel Corp, Trenton, Mich. Training and Audio Visuals Comm.--Dean A. Dexter (Chairman), Safety Supvr, Chicago Bridge & Iron Co, Oak Brook, III.; *W. T. McLean, Gen. Safety Engr, Gary Works, United States Steel Corp, Gary. Indiana; D. L. Johnson. Vice President, Penn. Mfg. Assn. Insurance Co, Chestnut East Building, Philadelphia, Penn.; R. M. Cowdrick, Supvr. of Safety, Bethlehem Steel Corp, Bethlehem, Penn.; Richard L. Kesling, Safety Engineer, Bethlehem Steel Corp, Bethlehem, Penn. Am-Ferrous Industry Committee--E. O. Petrie (Chairman), Safety Coordinator, Hunting ton Alloy Products Div, International Nickel Co, Huntington, W. Va.; John A. Turk, Mgr,, Safety & Env. Health, U. S. Metals Refining Co, Carteret, N. J.; J. E. Nichols, Dir. of Safety, Reynolds Metals Co, Reynolds Metals Bldg, Richmond, Va.; James J. Ryan, Gen. Safety Eng,, American Smelting & Refining Co, Denver, Colo.; Ray A. Pfohl, Safety & Security' Supvr, Ormet Corp, Hannibal, Ohio; J. E. Rous, Pit. Safety Engr, Kennecott Refining Corp, Baltimore, Md.; J. T. Mortimer, Safety Dir, Kenneeott Copper Corp, Ray Mines Division, Hayden, Arte.; R. D. Woodyard, Loss Prev. Supt, Olm Aluminum Co, Sheet & Plate Operations, Hannibal, Ohio.; R. H. Watson, Mgr. of Safety, Aluminum Co. of America, Pittsburgh Penn. Nominations Committee--*]. Patlyek (Chairman), Manager, Industrial Relations, East Chicago Works, Blaw-Knox Company, East Chicago, Ini.; *C. P. Vorhes, Manager of Safety, Jones & Laughlin Steel Corp, Pittsburgh, Penn.; *B,, D. Kent, Safety & Security Supervisor, Aluminum Company of America, Davenport, Iowa. Membership Committee--W. J. Schwabs* (Chairman), Supvr. oi Safety, The Youngstown Sheet & Tube Co, Youngstown, Ohio. Associations Committee--R. R, Hoffman (Chairman), Manager of Safety, Caterpillar Trac tor Co., Peoria, 111.; E. A. Bratton, Executive Dir, Steei Plate Fabr. Assoc, Hinsdale, 111.; John A. Janus, Dir.-Health & Safety Services, American Iron and Steel Institute, Washington. D. C. Steel Industry Committee--L. Wozny, Jr. (Chairman), Plant Safety Eng, Bethlehem Steel Corp" Sparrows Point, Md.; Clifton W. Fellows, Supvr. Indus. Safety Sect, Steel Division, Ford Motor Co, Dearborn, Mich.; Wm. Faison, Gen, Supvr, Safety, United States Steel Corp, Chicago, III.; W. R. Roblin, Manager of Safety, Allegheny Ludlum Steel Corp, Pittsburgh, Pa.; J. deforest, Industrial Relations Director, Inter national Steel Co, Evansville, Ind. Fabricating Industry Committee--A. R. Schuster (Chairman), Corp. Safety Dir, Allied Structural Steel, Industrial Construction Div, Minneapolis, Minn.; E. A. Bratton, Executive Dir, Steei Plate Fabr. Assoc, Hinsdale, III.; R. Citzort, Safety Dir, Frontier Steel, Muskogee, Okia. 20 Contest and Awards Committee--D. J. Wenzel (Chairman), Assistant Dir, Safety and Plant Prot, Inland Steel Company, East Chicago, Ind.; R. G. Ditimah, Corp. Safety Mgr, Interlake Steel Corp, Chicago, 111. West Coast Committee--R. C. Beckstead (Coordinator), Dir. Safety & Tech. Empl, Ameri can Smelting & Refining Co, Salt Lake City, Utah; J. W. Armstrong, Div. Mgr. Safety & Prot. Serv, Kaiser Aluminum & Chemical Corp, Oakland, Cal.; R. S. Jamar. Supvr. of Safety, Bethlehem Steel Corp, Seattle, Wash.; H. K. I-ambie, Dir. of Safety & Prot. Serv, Kaiser Aluminum & Chemical Corp, Oakland, Cal.; P P. Pelton, Jr, Safety Engr, Bethlehem Steel Corp, Pinole Point Works, Richmond, Cal.; T. T. Pindee, Safety Dir, Kennecott Copper Corp, Utah Copper Div, Salt Lake City, Utah; Harry Schwartz, President, Washington Pipe & Steel Co, Seattle, Wash.; Robert J. Wayne, Dir. of Labor Rel. and Safety, Kaiser Steel Corp, Oakland, Cal.; Edwin S. Wynkoof, Bethlehem Steei Corp, Pacific Div, Los Angeles, Cal. `Past General Chairman 21 PLAN NOW TO ATTEND THE 1971 NATIONAL SAFETY CONGRESS OCTOBER 25-28, 1971 / CONRAD HILTON HOTEL, CHICAGO 1972 The Congress is always a big week, a worthwhile week for the 13,000 safety people who attend. At the '71 Congress you can meet other safety people, with thesame problems and responsibilitiesasyourself. 1973 You can exchange views and ideas on accident preven tion, health, hygiene, and fire prevention ... on safety in industry, traffic, school, at home and on the farm. You can see the largest of all safety equipment exhibits at the Congress... an opportunity for you to make well- 1974 informed buying decisions for your company. This four-day educational program, planned and pre sented by the National Safety Council, can be your most thought-provoking, most worthwhile safety expe rience in 1971. Make plans early to attend the 1971 Congress and bring the other people in your organization who have safety responsibilities. FUTURE CONGRESS DATES 1971 1972 1973 1974 October 25-28 Oct. 30 - Nov. 2 Oct. 29 - Nov. 1 Sept. 30 - Oct. 3 N ATI <3 N AL SAFETY COUNCIL 425 NORTH MICHIGAN AVENUE . CHICAGO, ILLINOIS 60611. $**$**$$& >2 I v->- ^a o2 s-pi.. a q sr > i 3 .j -- O $ > 3 --P < t; -j n 5.n'y-mK & K' v r# \ fS * *o ; *- --' * ^ 't > t t o 33 S Z a s o Q N ational S afety Council 25, 27,28. N ational Safety C ouncil, Chicago, IL. Z> Ho a5O=)- w--o Hn8r doz Sc o 3 ati V3 s p *-* N3 B VD I> otn 3 o oo OoS3 ILI0--s)S3co e* ? oo O on > O dozCO Cl Cocto3 o g v-4o o 3. O e5g" < L O r o2 cwo TooJ '-K cn Oi-tj '* *i*4 NUJJ tn .5 O>-*5 or S o Z oc Ea oo po E cp/s ccCOr CD2-- B* Ooc CCOO O-t- 5o & (V o Z trr CO "aCO o pp PCPL osr rooo > 2 CO 3O' U o iQ 3ft) 3 (OD Q5' f3at) TJ o 3o <5Q' I CO