Piping Systems Practices

DOE-STD-1030-96

complete, and that they are removed before reenergizing the system.

4.2.3.3 Piping Systems Practices

Systems, portions of systems, and components that operate at

temperatures or pressures above ambient should be vented and, if

necessary for the performance of work, drained or cooled. Whenever

possible, an atmospheric drain and/or vent between the component to be

worked and sources of pressure to the component should be tagged in

the open position to depressurize the equipment and to accommodate

thermal expansion or contraction.

Systems that operate at high temperatures (e.g., greater than 200 F for a

water system) or high pressures (e.g., greater than 500 psig), should be

isolated from the work area by two closed valves in series, and a telltale

vent or drain valve between the isolation valves should be opened.

Systems containing hazardous materials should be isolated by two valves

in series and the isolated section should be purged. When any of these

conditions exists and two-valve isolation cannot be provided, specific

management approval should be obtained before performing work.

Exceptions to the two-valve isolation should be documented in the

lockout/tagout record and in the work package, and the workers should

be informed.

Verifying depressurization by breaking flanged connections, loosening

valve bonnets, removing instrument tubing, or other similar actions

should be avoided unless no other means for verifying depressurization

exists. Strict supervisory control and advance planning are required if

these methods are used.

4.2.3.4 Valve Practices

Pneumatically operated valves and solenoid-operated valves may be used

as isolation points if the following conditions are met:

A pneumatically or solenoid-operated valve that fails open is NOT

considered closed for lockout/tagout purposes, unless its power

(air) supply is isolated and the valve is forcibly closed with an