Pipe nipple too long

Reply

  #1  
Old 02-12-19, 10:39 AM
Member
Thread Starter
Join Date: Feb 2014
Location: USA
Posts: 70
Received 0 Votes on 0 Posts
Pipe nipple too long

Hi all and thanks in advance for your advice.

Last year a sloppy contractor installed a new bathroom at my place. Among the long list of regrettable mistakes, the shower supply pipe nipple is too long (photo 1) which causes the supply hub to sit approximately 3/8" out from the wall (photo 2). A generic piece of black rubber was used to try to mask the situation. The exact nipple length that I need is not a standard length, so my thought is to create a custom-length nipple using some spare half-inch copper pipe and two Copper C x MPT Adapter fittings (photo 3).

My question to you is: will a soldered custom-length nipple like the one I'm describing withstand the torque that I'll need to apply in order to connect the nipple to the female end of the pipe in the wall and to connect the water supply hub to the nipple?
 
Attached Images    
Sponsored Links
  #2  
Old 02-12-19, 10:45 AM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 23,115
Received 190 Votes on 179 Posts
Unscrew the pipe nipple and buy one that's 1/2" shorter. you should be able to find one somewhere.

If you want to make a custom fitting, that would probably work.
 
  #3  
Old 02-12-19, 11:44 AM
Member
Join Date: Nov 2002
Location: Northern Virginia
Posts: 709
Received 2 Votes on 2 Posts
XSleeper's idea to buy one that 1/2" shorter is the simplest and most direct answer. Another option that you may not be aware of: Home Depot can cut threads into a pipe like that one. You'll need to measure closely for the length you need, and they'll customize a slightly shorter version of the original nipple. This may be more robust than a soldered copper pipe.

At the HD near me the pipe threader is that oily trainwreck looking thing in the plumbing aisle.

Good luck with it, let us know how it goes!
Dave
 
  #4  
Old 02-12-19, 12:44 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
I'd suggest a hardware store not Home Depot. The one time I had HD custom cut a nipple it took me twenty minutes to show the plumbing associate how to do it.
 
  #5  
Old 02-12-19, 01:44 PM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 7,294
Received 60 Votes on 57 Posts
Not all HD have the pipe fitter or threader. Do what XSPLR says.
 
  #6  
Old 02-12-19, 04:03 PM
Member
Thread Starter
Join Date: Feb 2014
Location: USA
Posts: 70
Received 0 Votes on 0 Posts
Thanks for your replies! I originally did try to get the Home Depot plumbing guy to cut threads into a nipple that would've been exactly the correct length. The problem there was that the thread cutting machine has a minimum length requirement; I don't remember the exact number, but they can't cut anything shorter than 3 inches (or thereabouts). The nipple that's shown in the photo below is not the actual nipple that's being used; it was just a random pipe that we used as a placeholder.

I just measured the distance between the back of the hub and the wall with a digital caliper, and it turns out it's *exactly* 3/8". The problem that I fear with using a nipple that's 1/2" shorter than what's in there right now is not getting enough turns on the supply hub before i have to stop turning it (i.e. when the back of it is flush against the wall and the spout is pointing straight down)... I'm afraid of a leak inside my wall. Do you guys think I'm being unreasonable on that point? Is a good measure of plumbers tape or pipe dope enough to make up for a connection that's a turn or two short?
 
  #7  
Old 02-12-19, 04:09 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 17,799
Received 10 Votes on 8 Posts
youll be fine 1/2"shorter.I build it up a bit with tape..Id be using brass anyway.As thats what the elbow in the wall probably is.

Dis similar metals you know.......
 
  #8  
Old 02-12-19, 08:06 PM
Member
Thread Starter
Join Date: Feb 2014
Location: USA
Posts: 70
Received 0 Votes on 0 Posts
youll be fine 1/2"shorter.I build it up a bit with tape..Id be using brass anyway.As thats what the elbow in the wall probably is.

Dis similar metals you know.......
Lawrosa - would you mind educating me on the distinction that you're alluding to? The elbow is indeed brass (sharkbite to MPT)... I take it from your reply that using a nipple of any other metal would be a bad idea...?
 
  #9  
Old 02-13-19, 03:56 AM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 7,294
Received 60 Votes on 57 Posts
It's called a galling effect. Thread galling is a common, yet seldom understood problem with threaded fasteners. Galling, often referred to as a cold-welding process. In essence two different metals will tend to meld into one. I currently have what looks like an aluminum female hose attached to a brass male fitting. I cannot get them apart. I've used two pipe wrenched with extended pipe on both and still cannot remove them. I'm going to use a saw to cut it.
 
  #10  
Old 02-13-19, 04:56 AM
Member
Join Date: Nov 2002
Location: Northern Virginia
Posts: 709
Received 2 Votes on 2 Posts
Had to look it up to remember the name: galvanic corrosion can occur between dis-similar metals in the presence of an electrolyte. (Fresh water is a weak electrolyte.)
 
  #11  
Old 02-13-19, 08:20 AM
Member
Thread Starter
Join Date: Feb 2014
Location: USA
Posts: 70
Received 0 Votes on 0 Posts
Wow. Interesting stuff! My original question was whether soldered copper can be expected to withstand torque... But maybe torque isn't the biggest concern here. Based on the most recent replies re galling, my biggest fear now is that the copper nipple and the brass fitting become inseparable...!! Does the risk of galling go away if i use a sufficient amount of tape around the thread?? I assume the answer is no...
Seems the best bet for my particular situation is what lawrosa suggested, to get a brass nipple 1/2" shorter and use a bunch of tape on both ends to address the "too few turns" issue that i previously articulated.
 
  #12  
Old 02-13-19, 08:24 AM
XSleeper's Avatar
Group Moderator
Join Date: Dec 2004
Location: USA
Posts: 23,115
Received 190 Votes on 179 Posts
You don't have to worry about mixing copper and brass fittings at all. They are not reactive.
 
  #13  
Old 02-16-19, 08:04 AM
Norm201's Avatar
Member
Join Date: Sep 2013
Location: United States
Posts: 7,294
Received 60 Votes on 57 Posts
Thought I'd revive this thread for those who might be interested about dissimilar metals.

A customer brought this in the other day and asked if we could separate the nozzle from the hose. Refer to my post #9.This shows the galvanic effect of dissimilar metals.

This is a brass high pressure hose nozzle attached to a one of those ZERO-G hoses with an aluminum connection.

Brass is very reactive with aluminum, and brass screws will cause substantial corrosion of an aluminum base metal in a wet environment. As you can see from the pics the threaded portion has “welded” themselves together. The cross section with hose attached still cannot be separated.











 
  #14  
Old 02-16-19, 04:25 PM
lawrosa's Avatar
Super Moderator
Join Date: Dec 2010
Location: Galivants Ferry SC USA
Posts: 17,799
Received 10 Votes on 8 Posts
brass to brass is best. Brass to steel not so good. Galvanic corrosion.

Copper to brass also OK.

But you will twist the copper if you try what you say with the copper adapters. Or a high chance of it anyway.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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