There is an exemption for atmospheric storage and transfer of flammable liquids.
Are all atmospheric vessels excluded from coverage?
This exemption deals with storage and transfer of flammable liquids only. Atmospheric
storage and transfer of HHCs listed in Appendix A are not exempt. Further, atmospheric
storage tanks of flammable liquids may be covered if they are interconnected or in close
proximity to a covered process. Contractors should evaluate each situation based on local
site-specific considerations and document the technical basis for invoking this
Are activities such as atmospheric mixing, and blending of flammable liquids
covered under the Rule?
The requirements of the PSM Rule apply to such operations. The exemption for
atmospheric storage and transfer of flammable liquids does not apply to mixing and
blending operations, because such operations may generate static charges capable of
Are flammable liquids covered by the Rule when stored at atmospheric pressure in
tanks designed for pressure-service?
The Rule exempts storage of flammable liquids in atmospheric storage tanks in certain
instances. If a DOE contractor can reasonably show that the tank cannot be operated
above atmospheric pressure, then the exemption can still apply. The means to ensure
adherence to this operating practice should be reliable and documented.
Are flammable liquid storage tanks that are gas-blanketed for vapor control,
covered by the PSM Rule?
Under the PSM Rule, an atmospheric storage tank means a tank which is designed to
operate at pressures from atmosphere through 0.5 p.s.i.g. Therefore, flammable liquid
storage in tanks in which gas blanketing is maintained at or below 0.5 p.s.i.g. is exempt if
it is not connected to a covered process. Tanks containing 10,000 pounds or more of a
flammable liquid are covered by the PSM Rule if they are gas blanketed at a pressure
greater than 0.5 p.s.i.g.
Are warehouses that store HHCs considered covered processes if the total inventory
exceeds the TQ for Appendix A materials? For flammable materials? For
Warehouses are covered by the PSM Rule if the total quantity of an HHC stored in one
location exceeds the TQ for the particular HHC. If a warehouse is used to store
containers of Appendix A HHCs and, either individually or collectively, they exceed
their TQs, then the warehouse is covered under the PSM Rule. However, atmospheric
storage of flammable liquids is covered under other OSHA regulations (e.g., 29 CFR
1910.106) and is not covered under this Rule. Further, explosives manufacturing is
covered under the PSM Rule. However, storage and use of explosives outside the
manufacturing process are covered under 29 CFR 1910.109, Explosives and Blasting
Agents; not under the PSM Rule.