A pipe stress analysis (thermal flexibility analysis) predicts stresses in piping and loads on equipment resulting from thermal gradients, thermal transients, weights, pressure, and bolt-up strain. This study is typically required for piping that experiences high temperature fluctuations, or for long pipe runs such as hot piping to coolers or headers. Cases where equipment is sensitive to external loads may also require a pipe stress analysis.

The study methodology becomes more complicated for piping systems in vibratory service. As discussed below, the design must address conflicting requirements between the pipe stress analysis (where flexibility is desired) versus the mechanical vibration analysis (which requires stiff supports). Methods are available to manage this conflict and create an optimal piping design.