In steam, air, and gas systems, the blowdown connections at all low
points may serve as drains and the branch connections off the top of
piping headers may serve as vents.
Vent and drain connections are not required when their function is filled
by system branch connections, equipment vents, and drains or instrument
Lined Pipe. Special considerations should be given to the design of piping
systems lined with materials such as rubber, cement, glass, or epoxy. The
following guidelines should be considered in the fabrication and erection of such
Maximum spool lengths of lined pipe vary among suppliers.
The method of joining may be flanged, mechanical joint, screwed, or
welded prior to lining. Welding after the lining is installed is generally not
When using butterfly valves, consider a potential interference between
the valve disk and lining material, which decreases the inside diameter of
Freeze Protection . In cold climates external piping should be provided with
freeze protection. Preventing piping systems from freezing can eliminate costly
repairs and system outages. Freeze protection typically consists of either steam
or electric heat tracing. Economic considerations dictate which method is
Avoid routing piping along the inside of exterior building walls or un-
insulated siding in cold climates. Where possible, route piping near
radiant heat sources to prevent freezing.