Application cont'd - hdbk11010026

DOE-HDBK-1101-96

atmospheric pressure, then the exemption can still apply. The means to ensure adherence to

this operating practice should be reliable and documented.

14.

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.

15.

Are warehouses that store HHCs considered covered processes if the total inventory

exceeds the TQ for Appendix A materials? For flammable materials? For explosives?

Warehouses are covered by the PSM Rule if the total quantity of an HHC stored in one loca-

tion 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.

16.

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 trans-

fer (to storage).

17.

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 release.

18.

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..

19.

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).