High Pressure Expansion Joints Built for Polypropylene Process

In the piping required for one of the most often specified polypropylene processes, there is a need for very high pressure hinge, gimbal and tied expansion joints to reduce forces on gas compressor nozzles. These high pressure expansion joints are typically 18" to 48" pipe size. The design pressure ratings range from 350 psig to 700 psig.

The gimbal, hinge and tie rod hardware must be designed to withstand the full pressure thrust force of the expansion joint at the design condition as well as the hydrostatic test condition. The pressure thrust force can be 750,000 pounds at the design conditions, and over 1,000,000 pounds at the hydrostatic test condition.

All of these expansion joints are specified to be ply testable. The ply testable requirement for the polypropylene process expansion joints is complicated by the fact that there are two ply testable connections on each bellows and a measured flow must be established between the ply testable connections at the hydrostatic test condition in order to prove that the bellows are really ply testable. Experience is essential when designing for this difficult condition.

Many customers have chosen to install the Senior Flexonics Pathway “red top” leak indicator on the ply testable connections for these high pressure expansion joints to insure that there is a positive and recognizable indication of any leak which occurs. You can find out more about the “red top” by contacting Senior Flexonics Pathway.
Senior Flexonics Pathway has built many ship sets of high pressure expansion joints for polypropylene applications for customers including Bechtel, Union Carbide and Mitsubishi Heavy Industries and others, There is a learning curve associated with the design and testing of high pressure expansion joints. When high pressure expansion joints are required, remember that experiences does make a difference.
To inquire about high pressure expansion joints or “red top” leak indicators for any critical application, contact , Senior Flexonics Pathway, or visit our web site at www.myej.com.