Change 2, 30 December 1991
pipe for 12-inch (305 mm) size and larger. RTRP pipe and PVC pipe are also
acceptable. RTRP pipe and PVC pipe are available in 2 through 12-inch (51
through 305-mm) pipe sizes.
Thermal Expansion of Steel and Copper Pipe. Pipe expands with
temperature increases (such as between installation and operating
temperatures) as indicated in Table 12. Make provisions for the control of
expansion in any piping system where thermal expansion is a factor. Wherever
possible, provide for expansion of pipes by changes in direction of pipe runs.
Branch Lines. Where practicable, design branch line piping to
provide for expansion inside buildings. Expansion control of branch lines
should be designed so as to have no effect on mains.
Bends are to be factory fabricated except for RTRP
a) Loop Sections.
Loops may be furnished in sections to facilitate
delivery and handling.
b) Anchors. A reasonable distance between anchors for expansion
loops is 200 feet (61 mm) for 125 psig (861.3 kPa) steam system. Expansion is
usually kept at about 6 inches (150 mm) between anchors.
c) Cold Springing. Cold springing may be used in installations but
no design stress relief is allowed for it. For credit permitted in thrust and
moments, refer to ANSI B31.1.
Expansion Joints. Install expansion joints only where space
restrictions prevent the use of other means. When necessary to use, expansion
joints shall be in an accessible location and shall be one of the following
a) Mechanical Slip Joint. An externally guided joint designed for
expansion joints under 8 inches (203 mm).
b) Bellows Type Joint. Use these joints on steel pipe for thermal
expansion with stainless steel bellows, guided and installed according to
manufacturer's instructions. Make bellows or corrugations for absorbing
vibrations or mechanical movements at ambient temperatures of copper or other
materials suitable for the job conditions. A maximum travel of 4 inches (102
mm) is allowed for this type. RTRP expansion joints may be
polytetrafluoroethylene bellows type.
c) Flexible Ball Joints.
Install these joints according to