Water Pipe Expansion Joint?


  #1  
Old 12-29-06, 08:31 PM
G
Member
Thread Starter
Join Date: Jul 2005
Posts: 38
Upvotes: 0
Received 0 Upvotes on 0 Posts
Water Pipe Expansion Joint?

When I was helping a friend repair the 1 1/2" PVC water main to his house we found something neither of us had seen before. His house is in a rural mountain town on the side of a canyon. His main water pipe was leaking from a glued connection where two pipe lengths were connected under his cement driveway. (The driveway had been cemented after the pipe was laid) On either side of the driveway were two pipe unions with a sleeve that slid in and out. We removed one and took it apart. The sleeve was sealed with two O-rings that move with the sleeve as it slides back and forth. It looked similar to an expansion joint for PVC electrical conduit, but I have never seen or heard of such a thing being used with water pipes. I couldn't find any reference to it in my DIY plumbing books. We replaced the one we pulled with a regular 1 1/2" PVC pipe union. (neither of the unions was leaking, but we had to pull one side out to replace the broken joint, and decided to use all new pipe and fittings for the section that we replaced). I am puzzling over why this type of union was used, and am curious if they work well or tend to leak over time. I would guess that the original installer was trying to allow for expansion or contraction from the driveway (the pipe was only buried about 8" deep at that point), or possibly for shifting of the earth on the hillside. However my friend tells me that this same section of pipe broke about 5 years ago (in a slightly different spot just beyond the driveway), so I am thinking that the expansion joints didn't work the way they were intended. We needed to repair the water main quickly for the holidays, so we pretty much just replaced the broken section, but I am wondering if there is anything we should do to improve the design.
 
  #2  
Old 12-30-06, 04:23 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Join Date: Dec 2005
Location: USA
Posts: 36,607
Upvotes: 0
Received 11 Upvotes on 10 Posts
The coupling you are referring to is a close proximity coupling. It allows you to make repairs to pipes that are close together by sliding the entire sleeve up on one pipe and then aligning it with the second pipe and sliding it halfway over it, then tightening the nuts. Like you, I don't trust them, but they work amazingly well. They also allow for movement underground and reduce vibration in the piping.
 
  #3  
Old 12-30-06, 05:01 PM
G
Member
Thread Starter
Join Date: Jul 2005
Posts: 38
Upvotes: 0
Received 0 Upvotes on 0 Posts
Thanks, Larry. It's nice to know what they are called. The one we left in seems to be doing just fine even though I expected to start leaking since it had been sitting in the same position (probably) for many years before we moved it.

Greg
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: