Change 2, 30 December 1991
Steam Supply and Condensate Return. Piping shall conform to ASME
B31.1, except for underground prefabricated or pre-engineered type systems, in
which case the entire system shall conform to NFGS-02694.
a) If a separate pump condensate return system is used, it shall
conform to NFGS-02697.
b) For condensate provided as a part of an underground
prefabricated, pre-engineered system, include Mil. Spec MIL-P-28584 plastic
condensate piping in the specification as a Contractor's option for sites
classified B, C, or D. Plastic piping is optional but encouraged for sites
classified A. The Contracting Officer shall give specific approval for
plastic condensate piping in Class A systems. Take particular care that the
failure of high pressure steam drip traps shall not discharge high
temperatures and pressures into the plastic condensate piping.
High Temperature Water, Medium Temperature Water, and Low
Temperature Hot Water. Piping specifications and codes are as follows, except
for underground prefabricated or pre-engineered types, in which case the
entire system shall conform to NFGS-02694.
a) Piping. HTW metallic piping (450 degrees F maximum) (232
degrees C) and medium temperature water metallic piping shall conform to ASME
b) Joints. Welded joints are preferred. Threaded joints are not
permitted. Hold flanged joints to a minimum and use ferrous alloy gaskets in
such joints. Avoid the use of copper and brass pipe.
c) Valves. All valves shall have cast steel bodies with stainless
steel trim (no bronze trim). All valves shall be capable of being repacked
under operational pressures. Use gate valves only as shutoff or isolation
Natural Gas and Compressed Air. Piping shall conform to ASME B31.1
and B31.8 including guidance for abandoning existing gas lines. Note that
ASME B31.8 requires that abandoned gas lines be physically disconnected from
gas sources and purged prior to sealing. Shutoff valves are not an acceptable
means of disconnect. Cathodic protection systems on lines to be abandoned
should be evaluated for modifications required to ensure continuity of the
systems after abandoned lines are disconnected or removed. Provide excess-
flow (earthquake) shutoff valves in gas supply piping outside of each building
served in earthquake zones 3 and 4. In addition, provide flexible
connections. Gas piping and appurtenances from point of connection with
existing system to a point approximately 5 feet (1.53 m) from the building
shall conform to NFGS-02685.
Chilled and Condenser Water. Use Schedule 40 steel pipe in 10-inch
(254 mm) size and smaller, and use 1/2-inch (12.5 mm) wall thickness steel