Thermal Expansion and Expansion Pieces 

A pipeline will expand when it is filled with hot steam as its temperature rises from ambient air to the steam temperature. This amount of expansion can be significant as shown in the following tables.

Pipe Expansions from Ambient

Temperature of 70 Degrees Fahrenheit

Operating Pressure(psig)	Operating Temperature(degrees F)	Expansion of Carbon steel Pipe (in/100ft)	Expansion of stainless steel Pipe (in/100ft)
30	274.0	1.60	2.31
60	307.3	1.89	2.71
90	331.1	2.10	2.99
120	350.1	2.26	3.20
150	365.9	2.40	3.39
180	379.5	2.53	3.56
200	387.8	2.60	3.66
300	421.7	2.90	4.06

Pipe Expansions from Ambient

Temperature of 21 Degrees Centigrade

Operating Pressure(barg)	Operating Temperature(degree Celsius)	Expansion of Carbon steel Pipe (cm/100m)	Expansion of Stainless steel Pipe (cm/100m)
2	133.5	13.23	19.10
4	151.8	15.64	22.35
6	165.0	17.38	24.68
8	175.4	18.64	26.47
10	184.1	19.83	27.99
12	191.6	20.93	29.43
14	198.0	21.71	30.53
21	217.2	24.25	33.95

Allowance for the increase in length must be made in the piping system. This is usually done by adding expansion pieces. These are usually required in addition to the pipe supports, guides and anchors, which only control the movement of the pipe. However, some piping systems can be designed so that expansion stresses are naturally dissipated by the piping arrangement. In these cases, no expansion joints may be necessary.