Does the exemption for flammable liquids in atmospheric storage tanks apply if
connected to a process or process vessel?
No, it only applies to atmospheric tanks, containers, and pipes used only for storage and
transfer (to storage).
Are atmospheric storage tanks containing flammable liquids exempt even if they are
located adjacent to a covered process?
Atmospheric storage tanks containing flammable liquids are not exempt if they are
located close enough to a covered process that they could be involved in a catastrophic
For the purposes of the PSM Rule, does OSHA consider Department of
Transportation (DOT) approved containers to be atmospheric tanks?
Containers such as 55 gallon drums are considered to be atmospheric tanks. Therefore,
storage of flammable liquids in such containers, even if the quantity exceeds 10,000
pounds, would not be covered by the PSM Rule. However, such storage would have to
meet the requirements contained in the 1910.106, Flammable and Combustible Liquids.
What explosive substances are covered by the PSM Rule?
In 1910.109(a)(3), an explosive is defined as any chemical compound, mixture, or device,
the primary or common purpose of which is to function by explosion (i.e., with
substantially instantaneous release of gas and heat).
What is meant by the manufacture of explosives?
synthesizing, assembling, disassembling, and other activities involved in the making of a
product or device which is intended to explode.
Are flammable liquid and gas separation vessels associated with oil and gas well
drilling and servicing operations exempt?
Yes; however, these operations are often closely associated with a variety of vessels used
to separate and treat the flammable liquids and gases produced by the wells. Some oil and
gas production vessels may be excluded from coverage under the Rule by the
atmospheric storage and transfer exemption. However, other vessels associated with oil
and gas are covered if the flammable materials are stored above atmospheric pressure and
meet the 10,000-lb TQ requirement.
Please clarify the definition for the exemption of a normally unoccupied remote
facility? What does normally unoccupied mean? How remote is remote?
Normally unoccupied means that employees are not permanently stationed at the remote
location. This includes those sites where employees make periodic, scheduled visits (e.g.,
for preventive maintenance, sample collection, equipment calibration, or inspections).
Facilities meeting this definition are not contiguous with and must be geographically
remote from all other buildings, processes, or persons. There is no minimum distance