Return to the Plumbing Forum | Post a Follow-Up

fittings that don't fit

Posted by homebound (My Page) on
Thu, Nov 3, 11 at 20:26

I went to Big Orange and bought a length of L gauge 1/2" copper, a bag of Nibco 1/2 elbows and a bag of 1/2 couplings. As hard as I try, I cannot get the couplings to dry-fit onto the pipe, but the elbows are fine. All are acclimated to room temp, to rule that out. Is this a common problem and should I be buying from a plumbing supply instead? Thanks much.

Follow-Up Postings:

RE: fittings that don't fit

Did you oval the pipe when unrolling it?

You may need to get a flaring tool and use it to make the pipe round again.

Simply clamping it in the flaring tool usually rounds it out.

RE: fittings that don't fit

Are the couplings generic or name brand? It seems like the friendly neighborhood box-store sold you some inferior plumbing parts. No surprise here, I can't even find the necessary parts, at that place, to do ANY plumbing job!

I only buy plumbing parts from places that are organized and completely stocked. The HD should not even carry plumbing, IMO.

RE: fittings that don't fit

Per ASTM standards all outside diameter of Copper Pipe, both hard drawn (rigid) & Annealed (roll copper pipe) are made to the exact same size standards whether it is name brand or generic.

The outside diameter remains constant and the difference in wall thickness is made up on the inside diameter.

By example:
1/2" copper pipe both rigid & roll has an OD of 0.625".

type K ID is 0.527"
type L ID is 0.545"
type M ID is 0.569"

ASTM allows a slight tolerance on the ID (female opening) of fittings

by example:
for 1/2" fittings the ID of the fitting may be a maximum of 0.631" and a minimum of 0.627".

From my experience the couplings are usually the tightest and sometimes difficult to fit on the pipe, but they will fit however with only 0.002" difference they can be difficult unless the pipe is perfectly round and both the pipe & fittings have been properly deburred and cleaned prior to fitting.

Great care should be taken when handling copper pipe. Simply dropping a length of a concrete floor can be enough force to knock the end of the pipe out of round, making fitting a joint nearly impossible.

Copper pipe should only be cut with a good quality tubing cutter that is properly used. The tension should be increased as the cutter is rotated around the pipe. Simply placing the cutter on the pipe, cranking down the tension then rotating the cutter is enough to force the pipe wall out of round and seriously damage the cutter wheel on your cutter. (Those cheap little red mini cutters are at best useless)

Under no circumstances should a hack saw ever be used to cut copper unless you are tearing out old work and planning to dispose of the copper.

If you have a lot of fittings to clean here is a trick. Get on of the cheap wire fitting brushes with the simple wire loop handle and cut the handle off the shaft, then chuch the shaft of the brush in your cordless drill. You can then perfectly clean the ID of a fitting in a couple seconds.

RE: fittings that don't fit

Did the couplings say "Made in China" anywhere on the package?
I'd think Nibco to have tighter tolerance.
For soft solders to work properly, assuming the joint is clean and fluxed, the clearance need be at least .002" and less then about .007".
I haven't seen much quality pipe or fittings made in China.

RE: fittings that don't fit

Something was definitely wrong with that particular Nibco bag. Pipe was cleaned, deburred, round (I clip off an end from new pipe to avoid dings) etc. I bought some from a plumbing supply and also my local contractor supply and those were fine.

BTW, were you ever repairing a pipe, with phone ringing, dog barking, kid crying, etc. only to end up accidentally cutting the adjacent (perfectly fine) pipe right next to it? That about sums up my Friday afternoon. Grrr.

 o Post a Follow-Up

Please Note: Only registered members are able to post messages to this forum.

    If you are a member, please log in.

    If you aren't yet a member, join now!

Return to the Plumbing Forum

Information about Posting

  • You must be logged in to post a message. Once you are logged in, a posting window will appear at the bottom of the messages. If you are not a member, please register for an account.
  • Please review our Rules of Play before posting.
  • Posting is a two-step process. Once you have composed your message, you will be taken to the preview page. You will then have a chance to review your post, make changes and upload photos.
  • After posting your message, you may need to refresh the forum page in order to see it.
  • Before posting copyrighted material, please read about Copyright and Fair Use.
  • We have a strict no-advertising policy!
  • If you would like to practice posting or uploading photos, please visit our Test forum.
  • If you need assistance, please Contact Us and we will be happy to help.

Learn more about in-text links on this page here