Expansion Loops

Like all building materials, pipe materials expand and contract, and engineers must calculate for this; Corzan Piping Systems will expand about 1 inch per 50 feet of length when subjected to a 50-degree Fahrenheit temperature increase. Linear expansion does not vary with pipe size. Expansion is mainly a concern on hot water lines; it could be a concern on a cold water line installed in Southeast and Southwest parts of the country where summer temperatures can get very hot. And keep in mind that pipe is forgiving but fittings are not.

Expansion loop requirements for CPVC are not much different than those of copper. Generally, the effects of expansion can be controlled with changes in direction; an offset or loop may be required on a long straight run. One properly sized expansion loop is all that is required in any single straight run, but two or more smaller expansion loops, properly sized, can be utilized in a single straight run of pipe. Be sure to hang pipe with smooth straps that will not restrict movement, and remember that the pipe must be free to move for the expansion loops to work.

Per IAPMO IS 20, expansion loops are not required in vertical risers, provided the temperature change does not exceed 120 degrees Fahrenheit. Vertical piping must be supported at each floor as specified by the design engineer to allow for expansion/contraction, and piping should have a mid-story guide. Specify only hangers and straps that do not distort, cut or abrade the piping.

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