Type M Cu For Hot/Cold Water Lines Question

[Robert11]

Hello,

Live in a 35 year old house outside of Boston.

Had a leak in a Copper water pipe that the plumber finally found.

Unfortunately, I forgot to ask him if it was in a hot or cold line, as this might, perhaps, be meaningful ?

Anyway, what surprised me was that it was pinhole leak in the middle of a run.
Not at a joint or fitting, etc. Right in the middle of a line.

Apparently they used the thinnest Copper they could find when they built the place.

I used a caliper on it, and found it to be 0.028, which I guess is a grade M. (outside diameter of 5/8 inch)

But, it still should take the household pressure without any problem, I would think. True ?

The plumber replaced it with heavier wall stuff of approx. 0.038, which is probablyType L

Questions:

a. 35 years ago, was this (Type M) a "very common" Copper gage they used for household hot and cold water lines ?

b. Is it still allowed, or the Codes prohibits it now all over ?

c. What might make a pinhole leake in the middle of a clear run ?
I guess the pinhole can be considered as a corrosion type of breakthrough.

d. How common is something like this is the thinwall Type M tubing ? What causes ?

Any thoughts on this would be most appreciated.

Thanks,
Bob.

[nhmaster]

IPC and UPC both allow it's use but many states have adopeted an ammendment making illegal except for heating pipes. Most of us use type L.

[hj]

I have not used type "L" copper in a residence, EVER. "M" has always been the standard.

[jimbo]

You might want to investigate your water chemistry. Also water velocity and flow, like on a pumped recirc line, or a small line feeding a large demand, can cause erosion.

[Gary Swart]

I believe type M is still the standard. There may be some local codes or issues that specify type L.

[jadnashua]

The OD on copper like this is the same so any fitting will work (same with pex)...it is only the ID that changes with the wall thickness.

[AcidWater]

My ~40 year old pipes are failing from pinholes. I just finished struggling with fixing a second pinhole that was caused by yanking the pipes around in the process of putting in a coupling to fix the first pinhole. What a PIA.

I'm going to replace the whole system with PEX, except for the couple of risers are inside walls.

Pinholes are usually not found in the hot lines for some reason.

[Redwood]

Multiple pinholes are a case of aggressive water conditions.

The handle you are using hints at something...
Have you checked the PH of your water?
If so what is it?