The existing PSM standard (1910.119) applies in part to processes involving a flammable liquid or gas on site in one location in a quantity of 10,000 pounds or more. However, the existing PSM standard contains an exemption for “[f]lammable liquids stored in atmospheric tanks or transferred which are kept below their normal boiling point without benefit of chilling or refrigeration.” 29 CFR § 1910.119 (a)(1)(ii)(B). OSHA is considering clarifying this exemption in response to a decision by an Administrative Law Judge of the Occupational Safety and Health Review Commission. In Secretary of Labor v. Meer Corporation, No. 95-0341 (OSHRC 1997), an administrative law judge ruled that PSM coverage does not extend to flammables stored in atmospheric tanks, even if the tanks are connected to a process. As a result, employers can exclude the amount of flammable liquid contained in an atmospheric storage tank, or in transfer to or from storage, from the quantity contained in the process when determining whether a process meets the 10,000-pound threshold quantity.
OSHA is considering:
Changing the language in § 1910.119(a)(1)(ii)(B) to make clear that it applies only to processes in NAICS 4247 Petroleum and Petroleum Products Merchant Wholesalers.
Because of the particular conditions under which the potential rule amendment would have an impact, and the lack of information about the specific processes that might be used, the estimates of the additional entities and processes that would be covered by the proposed change are approximate. OSHA estimates that 656 entities would be added, along with 38,504 employees.
On May 12, 1997, OSHA issued a Regional Administrator’s memorandum acknowledging this decision (OSHA, 1997). The Meer decision was contrary to OSHA’s earlier interpretation of subsection (a)(1)(ii)(B), which was that the standard covered all stored flammables when connected to or located in close proximity to a process. The Meer decision was relevant in the Motiva refinery explosion and fire in Delaware City, DE, in 2001, and in an explosion at National Vinegar Company in Houston, TX in 1997. In the Motiva incident, sparks from repair work on an atmospheric storage tank ignited flammable vapors emitting from sulfuric acid stored in a tank. The quantity of flammable material in the tank was not ascertained. The potential applicability of PSM was based on the presence of flammable constituents within the tank liquid, which was primarily sulfuric acid. Even though the acid storage tanks were interconnected with the alkylation process, which was covered by the PSM standard, Motiva believed that the tanks were exempt from PSM coverage under theatmospheric storage tank exemption. Nevertheless, some flammable constituents in the liquid produced flammable vapors which ignited, resulting in one death and eight injuries (CSB,
2002a). As a result of this incident, the CSB recommended that OSHA:
[e]nsure coverage under the Process Safety Management Standard (29 CFR 1910.119) of atmospheric storage tanks that could be involved in a potential catastrophic release as a result of being interconnected to a covered process with 10,000 pounds of a flammable substance.
In the National Vinegar accident, fumes from an ethanol storage tank leaked and came in contact with live wires from a metering device, resulting in an explosion that caused one death and one injury. In this case, the company was cited for both lockout/tagout and for unsafe practices regarding a flammable material (OSHA, 2013a). Arguably, had the storage tank not been covered by the atmospheric storage tank exemption, the greater procedural development and process-hazard analysis under PSM might have prevented the incident.
The atmospheric storage tank exemption was originally intended to exclude processes that involved flammable liquid storage only, such as those at a fuel depot or fuel terminal (OSHA, 1997). However, this intention is not clear in the language of the standard, and a legal precedent has been set that also exempts atmospheric storage tanks that are connected to more complex operations that include processing.
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