Torsion refers to twisting one end of the bellows with respect to the other end, about the bellows centerline. Pipe expansion joints are not normally expected to accept torsional deflection since the bellows are essentially inflexible in this direction. The piping designer should carefully provide the system with restraints so that the pipe expansion joint is not expected to accept TORSIONAL DEFLECTION. This catalog contains the calculated torsional spring rate for each pipe expansion joint so that piping designers and analysts can provide the proper inputs for piping flexibility computer programs. If it is not possible or economically practical to relieve the pipe expansion joint of excessive torsional loading, then PT&P’s designers can provide anti-torsion features to the pipe expansion joints which prevent these loads from damaging the bellows elements.