Oversize 1/2" copper piping?


Old 02-03-10, 07:30 AM
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Oversize 1/2" copper piping?

I am replacing a bathroom sink in a two-story house built in the 1930s. The sink had compression fittings between the hot/cold pipes and the sink (no cutoffs).

It appeared be copper pipe, so I cut it off using a pipe cutter, so I could add the needed cutoffs. Since I could not finish the job that day, I went to Home Depot and got 1/2" shark bite caps (so I could turn the water on to the rest of the house). However, they don't fit. It's definitely NOT 3/4" pipe--it's just a bit larger than regular 1/2" copper pipe.

I had some other 1/2" copper fittings, and they won't fit over the cut pipe either (but some other 1/2" copper pipe I had DID fit into the Shark Bite attachments, so I'm sure it's not the Shark Bite stuff). Judging by the color of the cut metal I'm pretty confident it is copper piping.

Is there some sort of oversize copper pipe that used to be used? Will a big box store like Lowes/Home Depot carry what I need? I have done soldering in the past.

Any help is appreciated. The wife is giving me the stink eye because she can't take a shower....

Last edited by TODDMANQA; 02-03-10 at 07:34 AM. Reason: details
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Old 02-03-10, 11:17 AM
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Iím no plumber and a definite newbie. But Iím pretty sure copper pipe sizing is such that the OD is 1/8 inch larger than the stated pipe size. Like so:

3/8 pipe has OD 1/2
1/2 pipe has OD 5/8
5/8 pipe has OD 3/4
3/4 pipe has OD 7/8

The ID varies because the wall thickness will vary with the type of pipe (type L, K, etc.). But the OD is always the same. So a 1/2 copper pipe will always have an OD of 5/8. So I think what happens is when you buy a 1/2 inch fitting for copper it will have an ID of 5/8 and that will always fit over the 5/8 OD of the 1/2 inch pipe.

Iím pretty sure thatís all correct! Confused me to no end. Hope thatís correct and Iím not giving you hogwash! So you should be able to measure the OD to get your pipe size. But if itís iron pipe I think thatís a different matter.

for iron pipe 1/2 inch pipe has 0.840 OD
and 3/4 inch pipe has 1.050 OD etc.

Like I said Iím a newbie and you are probably correct that your pipe is copper. I donít even know if itís possible to use compression fittings on iron pipe. But if it is Ė then maybe your pipe is iron (or galvanized steel). Iím pretty sure you can test by using a magnet. It wonít stick to copper. But I guess if it was iron(steel) you would have had a more difficult time cutting it?

Hope the proís jump in!

Good luck!
Old 02-03-10, 12:08 PM
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Could it be the flexible pipe sold in coils? Or possibly a repair was done using A/C and refrigeration copper?

If the compression fittings were relatively modern...I would think you could just use compression valves. Time to get the micrometer for an exact measurement.

copper pipe

You know the longer this takes..the stinkier that eye is gonna get.
Old 02-03-10, 05:36 PM
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I might be able to shed some light on the tubing size confusion.
The problem with copper piping sizes occurs because it is frequently sold as a pipe size rather than a tubing size.

Steel pipe is sold in a measurement of the internal diameter of standard wall pipe which I believe is schedule 40.
Internal size varies with the wall thickness but the outside diameter is always the same and can use the same size fitting no matter the wall thickness.

The plumbing trade uses this same system when they refer to rigid copper tubing sizes but use the outside diameter when they refer to soft roll copper tubing.
The refrigeration trade uses the outside diameter for all types of copper tubing.

It's all the same tubing, just messed up sizing by the plumbers!

The 1/2" (5/8"od) ferrule doesn't fit because either the 5/8" tubing has possibly frozen at one time and expanded or it is actually 3/4" tubing size copper.

(Hmm, smilies seem to be messed up!)
Old 02-03-10, 06:49 PM
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I had a similar problem. Went to replace a WH and in order to stop the pipe from leaking and allow the customer to have water, I was going to use a couple of sharkbite caps. I had a heck of a time getting them on. It was Type N copper, which I feel may have been drawn a little large. Not sure if it was the type or what. Glad you confirmed my same experience.
Old 02-03-10, 06:59 PM
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Maybe it is the outside of a fitting, like a 90.
Old 02-04-14, 11:45 AM
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oversized 1/2 copper tubing

I am having the same issue. Soft Copper tubing has an Inside diameter of 1/2" - making the outside slightly larger. Shark Bites will not work. I already contacted sharkbite direct. He recommended using some type of compression fitting to reduce it to the normal 1/2" outside diameter copper pipe. Pipe and soft tubing are two different animals - to put it simply.

For now, the local plumbing store gave me a heavy wall plastic tube and some clamps. It's holding- but not forever. My search still goes on.

They did tell me that worst case: I will need to follow the tubing to its original starting point and replace it all with 1/2" copper pipe.

Good Luck.

Old 02-04-14, 04:22 PM
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You may be confused.
All copper pipe/tubing is made to a standard outside dimension........the inside measurement changes with the wall thickness.
It is explained in post #4.

The reference for a common size of copper piping is 1/2".
This common piping size is actually 5/8" outside diameter.
The confusion is that if copper is referred to as tubing you would call this size 5/8".

The piping size and tubing size are different numbers but both refer to exactly the same size of pipe and use exactly the same fittings.

This will all be thrown out the window if your pipes/tubing have frozen and expanded!

Last edited by GregH; 02-04-14 at 06:44 PM. Reason: Typo
Old 02-06-14, 03:07 PM
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Hi, Maybe you could solder a piece of 3/4 pipe ( not a fitting) over the 1/2 pipe that is too big then solder a 1/2 X 3/4 reducer on the end of the 3/4 pipe to bring back the standard size 1/2 Pipe.
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