Prepared with the help of the Safety and Fire Protection Committee of the Manufacturing Chemists' Association. Members are: Chaiman-J. S. Qwmn, Managn, Safety 6" Fire Protection, Du Pod; R. H. Albissn, Softy Manager, Chrmicnl D i e o n , Merck; H. A. E d , Director, Safety 6" Fire Prototcction, Mallinob.odt Chemical; A. H. Chistian, Cor@at# Safety Engineer, Amm'can Viscose; A. L. Cobb, Director o j Industrial Snfcy, Eartmn Kodak; C. U.D m M , M.D., Assistant Medicnl Director, Union Carbide; G. G. Flm'ng, Director of Safety and Plant Protection, CeImse; G. L. Gorbcll, Manager, Safety and Fire Protection, M m n t o Chemical; J . A. Hawthome, Chief Fire Protection &? Saf+ Engineer, NationaI Lad;A. L. King, Director of Loss Preumtion, Olin Malldrson; F. E. MacmJoy, Safety Director, W y d t t e Chemicals; S. M. Madhtchmn, Manager, Industrid Relotiar, D w , Chhical; S. F. Sporce, Director, Safety and Loss Pr&ion, Annn'can Cyanamid; N . G. Whitc, Manager, Industrial Hygim, &ll Chemical
This committee will meet in open Workshop Sessions in 1, and Los Angeles, October 2, 1962.
San Francisco, October
CHEMICAL SAFETY our own particular problem rn chemical satety has The Chemical Safety Workshops of the MCA were designed to help in such situations. MCA committee members are a panel with a wide and varied experience; in workshop sessions they share this background to solve problems posed from the floor. Several workshops have been held, many questions have been asked. A few questions are repeated at almost every meeting. Answers to these questions are the basic foundation on which to build a safe operation. T o answer them correctly the expert must often redefine the
Y probably never been described in a book.
I An ACS Council Committee on Chemical Sofety was ereafed Sepfember 10 by acfion of fhe Council Policy CommWh.. The new cornmiwee will be appointed by the presidenf of ACS to serve fhree years. If is charged fa rfudy ways of implementing recommendafions, by the Ad Hoc Committee creafed earlier for a preliminary rfudy of a posifive ACS program in chemical s&y, fhal: "The Society formally adopt a policy of responsibility and acfivity in fhe fleld of chemical safety and fhat if implement fhir policy by by fhe vigorous use of ifs publkafions and local Section focilifier by the formation of a
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INDUSTRIAL AND ENGlNEERlNG C H E M I S T R Y
problem, to pinpoint the true hazard. First, ask the right questicn-then you may find that the problem is really not unique. Here are some of these basic problems, common to most of the industry. We will have more next month. Answers to these shculd be a part of every technical man's thinking-hefore he asks the experts. Please discuss the merits of washing the oyer wifh new tralizing solutions, buffer solutions, normal sailm solution, or clew wafer. This question avoids the most important factor in washing the eyes-TIME. In many cases more can be accomplished with water in the first few minutes (or seconds if possible) that can be accomplished hy any other means 10 minutes later. Clean water should always be the first aid treatment. Flushing for 15 minutes with clear tap water may cause irritation, therefore normal saline is desirable. Buffer solutions and neutralizing solutions should be used only by or on standing orders of a physician. Can a s d e f y man accept wifh conftdence the published MAC values or ACGIH thnshold limits? The engineer can accept them with confidence-he can't use them blindly. These values are prepared hy competent professional people, working through responsible organizations. It is important to know that these figures are guides, and don't sharply differentiate safe from injurious atmospheres. They do not express the same thing-the threshold l i t value (TLV) of the American Conference of Government and Industrial
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a session with the experts A STAFF FEATURE
Hygienists (ACGIH) specifies a time-weighted average concentration, while the maximum allowable concentration (MAC) of the American Standards Association represents a ceiling value. The nature of the material will determine which is the more important. I n some cases, exceeding the limit results in discomfort; in other cases, death. The safety man will not handle these cases in the same way. We recommend reading the definitions given in the American Industrial Hygiene Association Journal (Vol. 23, No. 1, pages 45-7), and the discussion, pages 37 to 44 of the same issue. Do you flnd it necessary to analyze all raw materials added to a routine operation?
Yes and No. Certainly there is very little reason to analyze a chemical such as lime. But every item should be identified. Looking a t it may be enough. How serious i s static buildup in nonconducting liquid storage tanks? Can this charge be measured? When grounding tanks and pipe lines, i s it necessary to scrape the paint and expose bare metal?
Measuring static buildup is not the way to prevent static sparks. Static has caused a number of fires particularly in the handling of materials in petroleum base solvents. A static charge can be measured but this is difficult because the instruments available are not explosion-proof. A much better approach is to do everything possible to minimize the buildup of staticby humidifying the work area, grounding lines, elc.
Atmosphere within tanks must be kept outside of explosion limits. Grounding connection should be clean and metal to metal. A discussion of electrostatic ignition will be found in the March 1962 issue of Chemical Section Newsletter of the National Safety Council. When dry materials are poured from a plastic-lined shipping container into a flammable liquid, a static charge may cause a spark. Can you recommend a grounding device for the plastic-lined container?
No. Plastic manufacturers have been trying to develop a suitable container liner that will minimize static charge. Until these are in general use, the material should be removed with a metal scoop or dumped on a grounded metal chute, preferably at least 8 feet from a ventilated manhole on the vessel containing the solvents. Are case histories of chemical plant accidents available? Can w e arrange a clearinghouse of causes of major explosions and disasters?
The MCA has just produced a case history book that is probably the best available clearinghouse for chemical accidents. The NFPA is a valuable source where fire or explosion is involved. The National Safety Council’s industrial chemical section issues, in its monthly news letter, investigation reports of some disabling chemical injuries. MCA, NFPA, and insurance companies report such incidents to the chemical industry and the Association of Fire Chiefs. (Continued on next page) VOL. 5 4
NO. 1 0 OCTOBER 1 9 6 2
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Where do you store organic peroxides?
No safety device is more effective than the human brainif it is used
This information is well covered in the July 1962 issue of the h’ational Fire Protection Association Quartet&. The article “Organic-Peroxides-Storage and Handling” can be found on page 51. Can you suggest a design for housing pyrophoric materials, such as small cylinders of alkyls?
A suitable design would not be too different from that recommended for organic peroxides. The type of pyrophoric material must be considered, however. What precautions are taken to prevent buildup of explosive atmosphere in a plant sewer system?
Several recent accidents have occurred in truck transport of chemicals. When a fire occurs (perhaps through unrelated causes) the truck cargo may become very dangerous. Can the panel comment on prevention of such accidents and on protecting the public from the results?
Although truck transport fires involving chemicals arc serious, they occur infrequently considering the large amount of material that is trucked. Minimizing them is a very difficult problem. It will require much study, but some suggestions are : Limitation of quantities on each lodd --Very careful storage -Entire handling by special11 trained “ch-emical-transport dri\-ers” -Hazard identification hy NFPA symbol -For more hazardous materials, detailed emergency procedures should be prepared -Careful maintenance of tanks and accessory valves, manifolds etc. -Transport routes should be laid out carefully to avoid areas of heavy population and traffic congestion. Can the panel comment specifically on methods of storing, handling, and transporting organic peroxides?
This is all in the literature-some peroxides are quite safe while others are unstable. Some must be kept under refrigeration. Organic peroxides preferably should be kept segregated from other materials when stored, handled, or transported. The best single reference is the NBFU Research Report N o . 11, “Fire and Explosion Hazards of Organic Peroxides.” This excellent brochure covers the hazards, and the proper precautions in storing, handling, and transporting these materials. Mre would add oce comment-even small laboratory samples of some of these materials should be handled with caution. For example, benzoyl peroxide has been known to detonate when stored in a warm spot on a shelf. The standzrd precautions-isolation from areas of habitation and from combustibles and reactive materials, protection from physical shock and from sources of ignition, and protection from temperatures approaching the thermal decomposition point-should always be observed religiously. 32
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
The best precaution-don’t dump flammables in the sewer. Provide separate or safet) sewers for all departments processing flammable liquids. In addition, the sewer should be constantly flushed with a large amount of water and should be monitored b)- a multiple point sampling gas-vapor detector. This analyzer should provide an audible alarm ar. some predctcrmined concentration well below the 1oiLer euplosi1.e limit. In some plant?, large ventilating fans are set in operation b) the analyzer, to clear the semer. Proiisions should be made fcr shutting down the offending part of the plant Many chemical plants store large quantities of potentially dangerous materials. Do you work with the local fire departments to plan protection for the community in the event of a disaster? If police and fire departments were called in to help, how would you explain to them toxicity of materials and best firefighting methods?
Such cooperation is imperative if a plant is to ha\e a complete emergency program. Arrangements should be set up in advance. Chemical plants should invite the local fire chief to visit the plant periodically and become acquainted u ith potential fire hazards and the precautions which his men should take in an emergency. .41ro set up a mutual assistance arrangement with other planti in the community for handling major accidents. We zxplain to the chief of the fire department the hazards which may be encountered and the precautions recommended. M’e recommend use of the NFPA Hazard Identification Symbol. Command should lie set up in advance. In some plantr, the company fire chief is in command if the city should be called i n , In others, a trained technical employee is assigned to advise the city fire chief. Of what value are protective hand creams?
Protective creams are not a substitute for gloves. They should not be relied upon when handling corrosive or highly hazardous material. The?- provide considerable protection against solvents. I s there an accepted color code to identify contents of pipes? Are small containers color coded?
The ASA has a color code for identifying certain pipe lines but colors have a tendency to change, particularly in chemical operations. Labeling pipe lines and containers is a more satisfactory method.
Are there any advantages in storing compressed gas cylinders in the vertical rather than horizontal position? I s outdoor storage adequate, or what shelter i s required?
Recently, there were reports that it was hazardous to allow acetylene compressed gas cylinders to be positioned on their side. According to the Compressed Gas Association, these reports are untrue. But acetylene cylinders should be vertical in use to prevent leakage of acetone. We prefer to have all cylinders stored vertically, to avoid mistakes in using acetylene. Similarly, if hydrogen cylinders are present, we ground all cylinders. Some cylinders such as ammonia have to be emptied while in a horizontal position. It is preferable to store compressed gas cylinders where there is protection from the direct sun rays to prevent failure of the heat-actuated safety relief on some cylinders.
What progress has been made in standardizing reducing valves and gages for compressed gas cylinders?
The regulators themselves don't need to be standardized, The fittings should be in accordance with the ASA standard. Unfortunately many cylinder valves have not yet been standardized. Many believe that the present standard is inadequate and should be revised. Can standard commercial (ICC 3A) cylinders (regardless of age) be subjected to dry ice-acetone temperatures ( - 70" C.)? What happens to the metal if this i s done?
Contact the Compressed Gas Association before using compressed gas cylinders as part of your experimental equipment. The manufacturer of the cylinder or the supplier of the gas may be able to give you more information. Are floor drains safe in a chemical plant using flammable solvents? Should they terminate in dry wells, or city sewers?
Floor drains are necessary. They may not be totally safe but can be made as safe-as possible. Minimize amount of material spilled, and- use large quantities of water to flush. The drain should be trapped and should lead to a trap tank designed to keep solvents out of the sewer. Theoretically the solvent should float and be trapped in the tank which will pass only water to the sewer. UrLfortunately the system is not fool proof, but it can be be quite effective when properly maintained.
How far do you go in determining parameters of reaction safety? To twice expected pressure, for example?
Reaction safety begins with a sound knowledge of the chemistry involved in the reaction process. All possibilities of other reactions should be explored. Will material react with itself under certain conditions? What other materials may be present with which reaction will take place? After the potential reactions are identified, environmental circumstances which result in an uncontrolled reaction (temperatures, pressures, and catalyzing materials) are determined. We do not have a rule of thumb or pet method by which we determine parameters. Additional safety factors, of course, are inherent
in the ASME Pressure Vessel Code and the ASA Code for Pressure Piping. Based on tensile strength, or failure by rupture, about a 4 to 1 safety factor is provided. The safety record of the nuclear industry is notable. In handling fissile materials, they assume that a combination of two consecutive operating errors can occur.
Extreme conditions is a term with a rapidly changing meaning. How would you define it today from the safety viewpoint? What are the maximum temperature (high and low) and pressure conditions in use in chemical industry? What extra precautions are taken in such operations?
From a safety viewpoint, we should like the definition of extreme conditions to imply that equipment and procedures for such services require special and careful consideration. It logically follows then that the extreme conditions begin when equipment and procedures customarily used will not result in a safe plant. This depends primarily on the extent to which an over-all industry is accustomed to certain equipment and procedures. In the chemical industry, temperature levels above 1200" and below -100' F. require these special considerations. Operation a t pressure levels above 3000 p.s.i.g. cannot be considered as customary practice. For large vessels, even 500 p.s.i.g. needs special precautions. Many details of design require special attention to protect personnel and plant against the effects of failure of such equipment. A few examples are: -Provision of barriers around high pressure equipment or physical separation of the equipment -Minimize congestion around such equipment -Utilize a high degree of automatic control to ensure critical temperatures and pressures are at safe levels -Supplement this equipment with automatic shutdown and interlock systems -Provide a system of monitoring critical variables to detect malfunction or failure and to sound alarm -Provide final protection devices such as safety valves, rupture disks, or remote-operated drop-out valves. -Avoid inadvertent leakage or flow of material from the high pressure system to equipment rated at a lower pressure, such as back flow through a pump or leakage through check valves. Special attention should be given to positive shutoff of such lines and to adequate protection of lower pressure equipment -In high temperature service, protect equipment from thermal shock and subsequent failure. Particular attention is required for fire protection systems -Protection for blocked in-lines and equipment against hydrostatic pressures is extremely important in low temperature applications -Additional emphasis on 'basic safety considerations such as specially trained personnel, properly designed equipment, adequate safety devices, and proper attention to plant layout -There are many precautions but above all, don't tamper with the design ! The design of closures for high pressure vessels is an extremely difficult engineering job. Attempts to field-design such a closure may result in a serious accident. VOL. 5 4
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