It is the force generated by the expansion joint due to the pressure inside. As shown in the picture, we have seen several incorrect ways to calculate the thrust force of an expansion joint. Per the EJMA Standards, as well as ASME Section VIII B&PV Codes, the Pressure thrust is calculated by multiplying the Bellows Effective Area, corresponding to the mean diameter of the convolutions of the Bellows by the Pressure of the line.Read More
|Fabric Expansion Joints can withstand up to 3 PSIG (pounds per square inch gauge) or 100″ of water (H₂O) column (In pressure). If the pressure exceeds this amount, it is best to use a metallic expansion joint.|
In an axial piping system, the expansion joint should be located as close as possible to a main anchor. The first pipe guide should be located at a distance of 4 pipe diameters away from the expansion joint. The second guide should be located a distance of 14 pipe diameters away from the first guide. During installation, the expansion joint should be either welded or flanged into the piping system.
Hydro-test pressure & holding times vary for different design codes. For example, the ASME SEC VIII Div.1 general hydro-test pressure will be 1.3 x design pressure (minor factors may vary for this equation as well) and for piping design codes, the hydro-test pressure will be ASME B31.4,B31.8 1.5 x design pressure.