Analysis of FCC Expansion Joints Movement Test

The Turboexpander is an equipment that works under very critical conditions requiring very low allowable nozzle forces and moments. A solution to minimize the piping loads transmitted to the equipment is the use of expansion joints. A usual piping stress analysis normally is not enough to guarantee the turboexpander reliability. This paper shows the results obtained in a movement test realized on metallic bellows expansion joints (EJ) used in a turboexpander piping system. The EJ were designed according to the expansion joints manufacturer association code (EJMA), the diameters range from 457 to 2,898 mm, the material of the bellows is Inconel 625 LCF and the shell materials are “killed” carbon steel, for refractory lined EJ or stainless steel 304H. A special test device was developed to apply the design movements on the EJ at the factory. A digital dynamometer was used for data acquisition and the tests were performed on 16 expansion joints of two distinct types: hinged and gimbal. The EJ were pressurized with water during the test. The reactions and corresponding displacements for each step of the test were recorded during loading and unloading.