Wall thickness reduction due to expansion

[lhwingking]

Pipe expands when it is operated.

When it expands, will its wall thickness reduce?

If wall thickness will not reduce, how is it practically possible that wall thickness will not reduce when pipe expands? Material volume cannot increase out of nowhere.

If wall thickness will reduce, how is this reduction in wall thickness taken care in the design? Wall thickness is selected for a particular design pressure.

Please throw some light on this.

 

[racookpe1978]

Calculate that difference in wall thickness. 3600 psig, 12 inch pipe, 1050 deg F.

Now, tell me what matters.

 

[tbuelna]

If the "expansion" of the metal pipe is entirely due to increased temperature, then its volume will normally change. This property is described by coefficient of thermal expansion (CTE). As racookpe1978 points out, the tiny change in wall thickness of a pressurized pipe is usually not a concern in terms of flow. But changes in the pipe shape due to both pressure and temperature can be a concern in terms of how the pipe is constrained.

 

[prex]

And it is not true that volume cannot change under stress only at constant temperature. Poisson's ratio gives a measure of this: with ν=0.5 (elastomers) there is no change in volume due to elastic strain.

prex
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