Single expansion joints come equipped with bellow elements and end connections like pipe ends, flanges, weld necks and other optional features such as collars, liners, and covers. The bellows will deflect in any direction or any plane depend on the pipe movement. It is a cost effective design option but requires that the piping be controlled to the direction of the movements of the bellows unit. The pipe expansion joint should not be expected to control the movement of the pipe. If the piping analysis shows that the pipe expansion joint must accept axial compression, then the piping must be guided and constrained so that only that movement will occur.

Single Pipe Expansion Joint

Single expansion joints are least expensive elements and this expansion joint will not resist any deflections with any force other than the resistance of the bellows, which is a function of the spring rate times the deflection amount. Single Expansion joints do not  resist the pressure thrust along its axis, which is the product of the pressure times the effective, or cross sectional, area of the bellows.

This expansion joint will not resist any deflections with any force other than the resistance of the bellows, which is a function of the spring rate times the deflection amount. It is incapable of resisting the pressure thrust along its axis, which is the product of the pressure times the effective, or cross sectional, area of the bellows. Large diameter units, even with low pressures, can generate very large axial pressure thrust forces, which must be reacted by main and directional anchors. Otherwise the expansion joint will extend with disastrous results.