Flammable hazardous chemicals

Stanley M. Englund/ M S / Ch E / Fellow American Institute of Chemical Engineers Process Consultant, The Dow Chemical Company (retired). (Section Editor, Section 16 Introduction Hazard Analysis Storage and Handling of Hazardous Materials Reactive Chemicals Combustion and Flammability Hazards Hazards of Vacuum Hazards oflnei t Gases)... 

Process Hazard Analysis (PHA) (Dowell, 1994, pp. 30-34.) The OSHA rule for Process Safety Management (PSM) of Highly Toxic Hazardous Chemicals, 29 CFR 1910.119, part (e), reqmres an initial PHA and an update every five years for processes that handle listed chemicals or contain over 10,000 lb (4356 kg) of flammable material. The PHA must be done by a team, must include employees such as operators and mechanics, and must have at least one person skilled in the methodology employed. Suggested methodologies from Process Safety Management are listed in Table 26-1. 

Highly Hazardous Chemical - Toxic, reactive, flammable, or explosive substances, as defined in Appendix A of 29 CFR 1910.119, "Process Safety Management of Highly Hazardous Chemicals."... 

Hazardous chemicals is a broad categoiy that includes chemicals that may be toxic, flammable, corrosive, explosive, or luirmful to tlie environment. A toxic chemical is one type of a hazardous chemical. Toxic chemicals cause adverse health effects, such as severe illness or deatli, when ingested, inltaled, or absorbed by a lii ing organism. 

Two main hazards associated with chemicals are toxicity and flammability. Toxicity measurements in model species and their interpretation are largely the province of life scientists. Chemical engineers can provide assistance in helping life scientists extrapolate their resrrlts in the assessment of chemical hazards. Chemical engineers have the theoretical tools to make important contributions to modehng the transport and transformation of chemical species in the body—from the entry of species into the body to their action at the rrltimate site where they exert their toxic effect. Chemical engineers are also more likely than life scientists to appreciate... 

Flashing of vapour containing entrained mist may occur on venting equipment or vessels containing volatile liquids. This may create a toxic or flammable hazard depending on the chemical with steam the risk is of scalding. Rupture of equipment can produce a similar effect. 

Many hazardous chemicals are handled safely on a daily basis within chemical plants. To achieve this operating success, all potential hazards must be identified and controlled. When toxic and/or flammable chemicals are handled, the potentially hazardous conditions may be numerous — in large plants there may be thousands. To be safe under these conditions requires discipline, skill, concern, and attention to detail. 

The Finnish legislation (Pyotsia, 1994) classifies the flammability of chemical substances on the basis of their flash and boiling points. This is similar to the European Union Directives concerning hazardous substances. Also the Dow Fire and Explosion Index (1987) and Edwards Lawrence (1993) have been used similar approaches. 

Daniel A. Crowl, Ph.D. Professor of Chemical Engineering, Michigan Technological University Fellow, American Institute of Chemical Engineers (Section Editor, Process Safety Introduction, Combustion and Flammability Hazards, Gas Explosions, Vapor Cloud Explosions, Boiling-Liquid Expanding-Vapor Explosions)... 

Pyrophoric and other spontaneously combustible substances will generally be identified as such on their product literature, material safety data sheets (MSDSs), or International Chemical Safety Cards (ICSCs). If transported, these substances should be identified as DOT/UN Hazard Class 4.2 materials for shipping purposes and labeled as spontaneously combustible. For pyrophoric substances, the NFPA 704 diamond for container or vessel labeling has a red (top) quadrant with a rating of 4, indicating the highest severity of flammability hazard (NFPA 704, 2001). Note that pyrophoric materials often exhibit one or more other reactivity hazards as well, such as water reactivity. 

Injuries and fatalities from asphyxiation are often associated with personnel entry into inerted equipment or enclosures. Guidance on safe procedures for confined space access are provided by OSHA (OSHA, 29 CFR 1910.146, Confined Space Entry Standard, 2000), the American National Standards Institute (ANSI, Z117.1, Safety Requirements for Confined Spaces, 2003), Hodson (Hodson, Safe Entry into Confined Spaces, Handbook of Chemical Health and Safety, American Chemical Society, 2001), and BP (BP, Hazards of Nitrogen and Catalyst Handling, 2003). OSHA has established 19.5 vol % as the minimum safe oxygen concentration for confined space entry without supplemental oxygen supply (see Table 23-18). Note that OSHA imposes a safe upper limit on 02 concentration of 23.5 vol % to protect against the enhanced flammability hazards associated with 02-enriched atmospheres. 

Recommended Practice for Handling Releases of Flammable and Combustible Liquids and Gases Hazardous Chemical Code... 

Health and safety were absent from the list of priorities in the early decades of the synthetic dyes industry. Practical experience in the primitive working conditions of the time [64] no doubt made workers aware of the more obvious dangers, such as corrosive acids, flammable solvents and potentially explosive nitro compounds. Accidents must have occurred frequently, reminding victims and supervisors alike of the penalties suffered if hazardous chemicals were handled carelessly. 

CSB found significant gaps in OSHA process safety regulations designed to protect workers from highly hazardous chemicals, including reactive hazards. OSHA standards cover the hazards of some classes of substances, such as flammable and combustible liquids however, no OSHA standard specifically addresses reactive hazards. 

Steere, N. V. Storage requirements for flammable and hazardous chemicals. 

The toxic properties of chemicals can be found in a reference such as Hazardous Chemicals Desk Reference (Sax and Lewis 1987), which lists a number of chemicals alphabetically by name. For instance, n-butane is classified (by the Department of Transportation) as a flammable gas, is moderately toxic via inhalation, causes drowsiness, is an asphyxiant, poses very dangerous fire hazard when exposed to heat, flame, or oxidizers, and is highly explosive when exposed to flame. Information about safety and environment is also provided and updated by websites maintained by government agencies, such as the U.S. EPA, the National Institute of Occupational Safety and Health, and the National Safety Data Sheet. 

An obvious method for increasing the inherent safety of a production process is to substitute safer chemicals for more hazardous chemicals wherever possible. For example, flammable chemicals might be replaced by nonflammable chemicals explosive chemicals might be replaced by less reactive chemicals and highly toxic chemicals might be replaced by less toxic chemicals. 

Calcium carbide is classed as a hazardous chemical under Department of Transportation regulations. Domestic shipments are mainly in steel tote bins varying in capacity from 2.5—4.5 t. A small amount continues to be shipped in industrial wide mouth sted drums of 270 kg capacity. Containers must be marked "Flammable solid, dangerous when wet" and have the United Nations designation UN 1402. 

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