Application cont'd - hdbk11010029

DOE-HDBK-1101-96

If the incinerator is used to destroy either a flammable material or another HHC that is listed in

Appendix A, and the process contains a TQ of an HHC, the incinerator is covered. Generally,

fuel gas or natural gas systems are exempt if they are operated only for fueling process fur-

naces or utility boilers that are also not covered. However, if fuel gas or natural gas is used to

fuel a covered process, then the fuel gas or natural gas systems associated with the process are

covered. LPG storage and handling systems used exclusively to fuel vehicles are not covered.

A natural gas supply used to "sweep" a flare system is not covered unless the flare system is

covered for other reasons.

30.

Must the boundary of a covered process containing many interconnected vessels always

extend in all directions to the process unit's battery limits?

No. In many cases, DOE contractors may wish to define the physical limits of coverage based

on an evaluation of the threat of a catastrophic release of an HHC. Contractors are encouraged

to document the technical basis of their coverage decision for those cases subject to interpreta-

tion.

31.

A continuous process uses an HHC, but the HHC inventory exceeds the TQ in only one

vessel. Upstream of this vessel, except for the HHC supply system, there are no HHCs.

Because the HHC is consumed almost entirely in the vessel, normally only trace amounts

of the HHC exist downstream of this vessel. Is this process covered, and if so, how far

upstream and downstream do the covered process boundaries extend?

This process is covered. DOE contractors may wish to adopt the following approach. Extend

the boundary upstream and downstream to the point at which there is no reasonable potential

for a catastrophic release. At least the equipment immediately upstream and downstream from

the vessel containing the TQ of the HHC should be included in the boundaries of the process.

32.

A batch process uses an HHC, above its TQ, in one of its many processing steps. Is this

step, and its associated equipment, a covered process?

Yes. In addition, the same strategy discussed in Questions 30 and 31 may apply to the equip-

ment used in a batch process. A DOE contractor may apply a similar approach in setting the

boundaries around the processing steps that are covered under the Rule.

33.

Must the inventory of HHCs contained in offsite interconnecting pipelines be included in

the inventory calculation? If so, can reliable isolation devices at the fence line be used to

limit the inventory used in the coverage calculation?

DOE contractors should consider the amount of material that could reasonably be released if a

loss of containment occurred onsite. If this amount represents a catastrophic release to the

workplace (i.e., it exceeds the TQ for an HHC), then the process is covered. OSHA has not yet

recognized the use of isolation devices as adequate mechanisms to limit inventories for pur-

poses of determining coverage under the PSM Rule. However, if isolation devices are consid-

ered as preventative or mitigative control measures against catastrophic releases, then docu-

mentation should be provided as to their effectiveness and reliability.