A fire protection engineer asked about a distribution center storing consumer aerosol products — shaving cream, hair spray, antiperspirant — in metal containers holding up to 33 ounces of product with flammable gas propellants (butane, isobutane, propane). The facility ships to retailers, is not itself a retail site or manufacturer, and complies with NFPA 30B and the International Fire Code. Does PSM apply once the aggregate propellant weight tops 10,000 pounds?
OSHA answered yes, walking through the logic: the propellants are highly hazardous chemicals under the standard; the quantities exceed the 10,000-pound threshold; the PSM definition of a process includes separate vessels located such that a highly hazardous chemical could be involved in a potential release, treated as a single process; individual can amounts must be aggregated when containers are co-located; fire scenarios show a reasonable potential for release; and engineering and administrative controls don't determine process boundaries. Critically, the retail exemption doesn't apply to distribution centers. Fire code compliance helps but doesn't decide PSM coverage — those codes function as recognized and generally accepted good engineering practices within a PSM program.
For the practical math, OSHA said to check product Safety Data Sheets or contact manufacturers for the propellant weight per can, then multiply by the number of co-located containers. If the threshold quantity is exceeded, a PSM-covered process exists. Fluctuating inventory doesn't eliminate coverage when the employer has not instituted control measures to keep the inventory below the threshold quantity.
OSHA also confirmed that its publication 3909-03, Process Safety Management for Storage Facilities, is guidance rather than a regulation — though it addresses mandatory requirements of the standard that apply to storage facilities.