Obviously, the larger the pipe diameter and consistency of the process fluids will vary this effect tremendously. If the piping is properly supported, the influences can be eliminated completely. There are piping manufacturer recommendations as to the proper location and distance between hangers.
As a rule of thumb when cast iron is used for pressure the distance between hangers should not exceed 12 feet. When cast iron is used for soil pipe, the recommendation is 10 foot maximum spacing. According to ITP’s Pipe Trades Manual, hanger locations for steel pipe systems varies based on size. This range is from 7 feet apart for 1 ¼” diameter piping to as far 33 feet apart for 24” diameter piping.
Regardless of the size, it is a good practice to walk your piping systems to locate potential influences caused by broken, loose, missing or incorrectly spaced pipe hangers.