Stainless Bellows Expansion Joints in a Process Air Line
Stainless Bellows Expansion Joints in a Process Air Line
(OP)
Here is my situation, My company has installed about 40 or more of these Stainless Bellows expansion joints in a process air line. The diameters of pipe are ranging from 16" down to 2". The operating pressure of the system is about 9 psi. @ 200 degrees. The expansion joints were shipped minus the "Shipping Bars" that usually hold the joint to a specific "over all length". Each joint is designed to consume 2" of contration and expansion - total 4" movement. Using a tempature delta of 150 deg. and the longest run of pipe involved between expansion joints, I total approx. 1/4" of movement. Now on to the problem...durring installation, some of the EJ's were installed at "plus or minus 1/2" of the original overall length. The manufacture of the joints has given me a letter confirming that this in no way will damage or hinder the operation of the EJ in the system that it is being required to operate within. However, I am looking for any documentation that could show that these joints also have a manufacturing tolerance or an installation tolerance. I need to show that there is no concern for the operation of this system and that I provided a joint with more movement than ever could be required by this system therefore allowing myself some movement within the range of the EJ for installation purposes. Thank You for any help in this matter Chad Rowe Project Superintendent





RE: Stainless Bellows Expansion Joints in a Process Air Line
I actually had one bellows joint that was installed with an initial radial deflection of about 3/4", when it was only designed for a maximum of 1/4". After checking with the manufacturer, we pulled the joint, re-aligned the piping in question, pressure-tested the expansion joint to make sure we hadn't cracked any welds, and put it back in service with the proper misalignment. It's been in service now for about 5 years with no problems.
RE: Stainless Bellows Expansion Joints in a Process Air Line
Although, for future reference, it is very bad practice to use EJ's to make up piping misalignment like that. One of the main reasons joints are shipped with shipping bars is to keep construction guys from going exactly what they did to you. I'm really surprised a vendor would ship joints w/o bars.
I must confess, I've also never heard of using expansion joints in air piping. Wonders never cease
Edward L. Klein
Pipe Stress Engineer
Houston, Texas
"All the world is a Spring"
All opinions expressed here are my own and not my company's.
RE: Stainless Bellows Expansion Joints in a Process Air Line
RE: Stainless Bellows Expansion Joints in a Process Air Line
All well and good,but I suspect whatever documentation you need is going to have to come from the joint mfg.
Good luck
RE: Stainless Bellows Expansion Joints in a Process Air Line
Actually I hate using expansion joints unless absolutely necessary just for your reason - if you get a bad fitter or designer they take one look at that joint, which is usually just to compensate for thermal expansion in a single direction, and consider the joint a fudge-factor for putting the system together. "We're out half an inch? Don't worry about it, we'll just pull the expansion joint to fit, no need to waste 10 minutes adjusting pipe supports to eliminate the misalignment properly" The part that always bothers me is that the guys installing the joints rarely, if ever, even know how much deflection the joint was designed for.