Most of our pipelines are large steam lines run cross country. We have problems with ground subsidence which causes displacements between pipe anchors.

How should we be managing and designing for this problem? Should we be adding some extra displacement to the thermal range Ignoring it and calling it cold forming (ie just let the pipe bend, which is what has been done for the last 50 years with no failures)

These ground strain's are non cyclic and causes self limiting stress.

We use B31.1 code for the design and the pipes are grade B carbon steel.