Questions cont'd - doe-hdbk-1101-20040029

DOE-HDBK-1101-2004

27.

A process normally contains no HHCs, but under upset conditions, the process

could generate an HHC in an amount in excess of the TQ. Is the process covered?

Processes are covered by the Rule only if, at any time under normal processing

circumstances, they contain an HHC in excess of its TQ. The ability to generate an HHC

during an upset condition does not invoke coverage by the PSM Rule. However, when

DOE contractors recognize situations with significant potential for safety and health

impacts, they should consider applying appropriate PSM practices to protect worker

health and safety.

28.

An Appendix A chemical is created within and then immediately consumed in a

process. Does the brief existence of this short-term intermediate chemical cause this

process to be covered by the Rule? If the inventory of this intermediate can only

exceed the TQ under upset conditions, is it a covered process?

A process is covered if, at any time in one location, it contains an HHC in excess of its

TQ. This process is covered as long as the intermediate existed under normal conditions

in the process. If the intermediate chemical could exist above the TQ only under upset

conditions, then the process is not covered. However, when DOE contractors recognize

situations with significant potential for safety and health impacts, they should consider

applying appropriate PSM practices to protect worker health and safety.

29.

Please clarify the exemptions for the following types of operations covered under the

workplace fuel criteria: hazardous waste incinerators, refinery fuel gas systems,

liquefied petroleum gas (LPG) storage for vehicle fueling, natural gas systems for

utility boilers, and natural gas systems used to sweep flare systems.

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 furnaces 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 interpretation.

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?