The First step in the selection of an expansion joint is to compute the exact change in the linear dimensions of the piping system; the next is to consider a safety factor.  The actual expansion of a 100-foot length of pipe has been computed at different temperatures for various materials commonly used in piping.

Given:
150-foot-long, 6" diameter steel steam line
Maximum steam temperature in service........................380ºF.
Minimum winter temperature to be encountered..........  15ºF.

Calculated Traverse:
From The Table Below, the expansion of carbon steel pipe at:

380ºF...............................3.060 in. per 100 ft. of pipe
  15ºF...............................  .111in. per 100 ft. of pipe
Difference.........................2.949 in. per 100 ft. of pipe

For 150 feet of pipe the expansion is proportionately larger.

Thus, Calculated traverse = 150/100 X 2.949" = 4.42"