What is the determining factor on whether or not an expansion joint is needed
What is the determining factor on whether or not an expansion joint is needed
(OP)
I have a long length of chilled water pipe. 2-1/2" copper pipe drops down through a floor and runs in a tunnel for 300' with no elbows. Then the pipe turns 90 degrees and runs an additional 20' The pipe then turns back up through the floor. Nothing is rigidly locked above the floor on either end, so there is "wiggle room"
It is chilled water pipe that will be operating at 40 degrees F. Absolute worse case ambient during installation will be 100 deg F. I can calculate the the expansion easy enough; it is approximately 2" along the 300' run. My question is, how do I know when expansion compensation is necessary? How do I justify when to install expansion joints ---- and when not to. I need to be able to make the case either way.
It is chilled water pipe that will be operating at 40 degrees F. Absolute worse case ambient during installation will be 100 deg F. I can calculate the the expansion easy enough; it is approximately 2" along the 300' run. My question is, how do I know when expansion compensation is necessary? How do I justify when to install expansion joints ---- and when not to. I need to be able to make the case either way.





RE: What is the determining factor on whether or not an expansion joint is needed
- First try routing (with anchors and guides) for flexibility and clearance for expansion movement.
- Second try routing with Loops, anchors and guides to control expansion movement.
- Last choice accept the need for Expansion Joints.
Sometimes its possible to do all the right things and still get bad results
RE: What is the determining factor on whether or not an expansion joint is needed
RE: What is the determining factor on whether or not an expansion joint is needed
Your pipe is small diameter. The run is long, but temperatures are not excessive and you have 20' on the end in which to do some flexibility bending. The moment developed there should not be all that great. I doubt if you need an expansion joint. You could try using an anchor to force growth to the opposite direction, away from your floor penetration. Maybe try two anchors, one at each end of the 300' run and S-snake the pipe a little in the middle. Expn joints are generally reserved for placement nearby sensitive equipment where piping is extremely tight, with no room for any expansion loops or doglegs and expansion directional control by use of anchors was found to be ineffective.
RE: What is the determining factor on whether or not an expansion joint is needed
Without that it is difficult to exactly determine if you need an expansion joint or not, but from your description ( an isometric sketch would be useful) it looks like you have enough flexibility. The key is working out where it is in fact finally fixed ( it must be fixed to something somewhere) and what the likely forces are at that fixed point.
As this pipe will be in tension you don't really have too many issue with the pipe buckling or falling off simple supports, but you will need guides somewhere to limit movment.
I echo all my fellow posters - use expansion joint s only if nothing else works, e.g. a straight line between two fixed points.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: What is the determining factor on whether or not an expansion joint is needed
in my opinion the use of expansion joint can be useful when:
- you have high temperature and a piping routing with limited space..so you cannot introduce flexibility by working on the piping routing
- you have very low allowables at connection to be respected
But the starting point is that first of all I Always try to solve the problems by working on piping routing and supports....the last choice is the use of expansion joint and hangers
Lorenzo
RE: What is the determining factor on whether or not an expansion joint is needed
RE: What is the determining factor on whether or not an expansion joint is needed
RE: What is the determining factor on whether or not an expansion joint is needed
RE: What is the determining factor on whether or not an expansion joint is needed
Per your Post:
Installation Temp. = 100 degrees
Max Low Operating Temp.= 40 degrees
Delta = 60 degrees (but temperature wise in the opposite direction)
So, use the coefficient of expansion for Copper and calculate it as a negative (Shrinkage)and that should be close enough.
Sometimes its possible to do all the right things and still get bad results
RE: What is the determining factor on whether or not an expansion joint is needed
My concern would be at the elbow, if threaded, is not designed to take much transverse torsion.
I used to count sand. Now I don't count at all.