Threshold quantity

For chemical faciUties in the United States, hazard analysis is not an option if inventories of hazardous chemicals are maintained in amounts greater than the threshold quantities specified by the Occupational Safety and Health Administration (OSHA) regulation 1910.119. Many faciUties are finding that hazard analysis has many benefits. The process or procedure often works better, the quaUty of the product is improved, the process experiences less down time, and the employees feel more comfortable in the work environment after a hazard analysis has been completed. 

The Nevada Chemical Catastrophe Prevention Act (NCCPA) was developed in response to the two incidents in the late 1980s which occurred in Nevada. This act and its program regulations, enacted in 1991, became effective in 1992 (29,30). The legislation appHes to faciUties handling any of the 128 listed chemicals in quantities above a threshold quantity. 

This recommended practice is intended to apply to faciUties that (/) handle or store flammable or explosive substances in such a manner that a release of ca 5 t of gas or vapor could occur in a few minutes and (2) handle toxic substances. The threshold quantity for the toxic materials would be determined using engineering judgment and dispersion modeling, based on a potential for serious danger as a result of exposures of <1 h. 

The regulation Hsts 137 toxic and reactive substances and a threshold quantity for each. The regulation also appHes to flammable Hquids and gases in quantities of 10,000 lb or more (>4.5 metric tons), except hydrocarbon fuels and Hquids stored in unpressuri2ed, ambient temperature tanks, as weU as to the manufacture of any quantities of explosives (see Exlosives and propellants) and pyrotechnics (qv). 

Explosibility and Fire Control. As in the case of many other reactive chemicals, the fire and explosion hazards of ethylene oxide are system-dependent. Each system should be evaluated for its particular hazards including start-up, shut-down, and failure modes. Storage of more than a threshold quantity of 5000 lb (- 2300 kg) of the material makes ethylene oxide subject to the provisions of OSHA 29 CER 1910 for "Highly Hazardous Chemicals." Table 15 summarizes relevant fire and explosion data for ethylene oxide, which are at standard temperature and pressure (STP) conditions except where otherwise noted. 

If a U.S.-based toll project requires threshold quantities of feedstock, intermediate or finished product that are considered ... 

Section 313 reporting Is required If threshold quantities are exceeded. The thresholds vary depending upon the year for which the report Is submitted and separate thresholds apply to the amount of the chemical that is manufactured, processed, or otherwise used. 

In the example below, it is assumed that the threshold quantities for manufacture, process, or otherwise use (25,000 pounds, 25,000 pounds, and 10,000 pounds, respectively, for 1989) have been exceeded and the reporting of listed chemicals is therefore required. 

Reportable Threshold Quantity Ptannlng Quantity Notes (pounds) (pounds)... 

Aggregate Threshold Quantity - The total amount of a hazardous chemical contained in interconnected or nearby vessels that may be adversely affect an accident. 

Threshold Quantity - As defined in 29 CFR 1910.119, the minimum amount of a toxic, reactive, or flammable chemical judged by OSHA as being capable of causing a catastrophic event. The threshold quantity triggers application of the rule s requirements, tonnes - A metric ton, i.e., 2,200 lb. 

Most or the incidents described were the result or not rollowing good engineering practice. Some violated the law, and many more would if they occurred today. In the United States, they would violate OSHA 1910.147 (1990) on The Control of Hazardous Energy (Lock Out/Tag Out) and the Process Safety Management (PSM) Law (OSHA 1910.119, in force since 1992). which applies to listed chemicals above a threshold quantity. The PSM Law requires companies to follow good engineering practice, codes, industry consensus standards, and even the company s owm standards. OSHA could view failure to follow any of these as violations. 

The Occupational Safety and Health Administration s regulation 29CFR1910.119 provides a regulatory framework for process safety management. This regulation applies to facilities handling a spedfied list of chemicals above indicated threshold quantities. 

Threshold quantity for accidental release prevention 10,000 pounds EPA 1998e (40 CFR 68.130)... 

Toxic and reactive highly hazardous chemical which presents a potential for a catastrophic event at or above the threshold quantity 1,500 pounds OSHA 1998a (29 CFR 1910.119 Appendix A)... 

The strength and extensibility of a noncrystallizable elastomer depend on its viscoelastic properties (28,29), even when the stress remains in equilibrium with the strain until macroscopic fracture occurs. In theory, such elastomers have a time- or rate-independent strength and ultimate elongation, but such threshold quantities apparently have not been measured, though rough estimates have been made (28,30). 

An unplanned event or sequence of events that has an undesirable consequence. Aggregate Threshold Quantity... 

Determine (a) whether the following chemicals are covered under the PSM regulation (29 CFR 1910.119) and (b) their threshold quantities acrolein, hydrogen chloride, phosgene, propane, ethylene oxide, and methanol. 

Determine whether the following chemicals (a) are covered under the RMP and (b) are listed as toxic or flammable. If they are listed, (c) what are their threshold quantities The chemicals are ammonia (anhydrous), hydrogen selenide, formaldehyde, methane, and ethanol. 

In reviewing the results of Problems 3-1 to 3-4, describe why the threshold quantities are lower for the PSM-regulated chemicals than for the RMP-regulated chemicals. 

Some of the parameters that affect VCE behavior25 are quantity of material released, fraction of material vaporized, probability of ignition of the cloud, distance traveled by the cloud before ignition, time delay before ignition of cloud, probability of explosion rather than fire, existence of a threshold quantity of material, efficiency of explosion, and location of ignition source with respect to release. 

In Europe, the Seveso II Directive [96/082/EEC] applies to facilities handling threshold quantities or greater of listed "dangerous substances," including a number of chemicals classified as reactive. Prevention program... 

The OSHA PSM Standard lists 131 distinct chemicals with toxic or reactive properties.40 It includes 25 chemicals with an NFPA rating of 3 and 13 chemicals with an NFPA rating of 4. PSM applies to processes that involve listed chemicals at or above threshold quantities and to processes with flammable liquids or gases onsite in one location, in quantities of 10,000 pounds or more. Companies that manufacture explosives and pyrotechnics are also required to comply with the standard. 

EPA promulgated the Accidental Release Prevention Requirements (40 CFR 68), which contain the list of regulated chemicals and requirements for facilities possessing more than a threshold quantity of a listed chemical in an individual process. Covered facilities are required to implement a risk management program and submit a risk management plan to EPA. 

The criteria include any fire or explosion causing more than 25,000 in property damage an episodic loss of containment incident of a chemical in excess of the threshold quantities listed in 40 CFR 355.40, Appendix A an episodic loss of containment incident involving more than 5,000 pounds of a flammable substance or any fire, explosion, or chemical release that involves one or more fatalities or serious injuries. 

Processes having a reactive hazard with a heat of reaction of 100 calories per gram will be regulated under the NJ TCPA when the quantity of reactive hazard contained in the process equals or exceeds the threshold quantity calculated to result in a 2.3 psi overpressure wave endpoint at a distance of 100 meters or a lesser distance to the source boundary. 

---