What the... ? Corroding copper pipes - pinholes.

[blondini]

... very slow weeps from apparently uncorroded sections of pipe, like this:

pipe1

• jlacd
• 18 Nov 2008
• 1

Cheer me up, someone!

Nocando. I think you need to replace.

Have seen exactly the same thing in my own home. A few years ago I was replacing the kitchen ceiling and discovered a damp area that had been hidden. Thought it was from poor sealing around a shower but there was this tiny bead of water that just kept appearing on a copper pipe that I'd wiped dry several times. It was a pinhole and at the time I put it down as a one off.

More recently I was doing some work in the bathroom and I was easing the copper cold feed for the loft tank away from the wall when it sprung a leak or three straight out of the wall of the pipe! I cut out and renewed the section, a temporary bodge with plastic and pushfit, but the copper just started leaking somewhere else. I found that it was literally rotting from the inside and had become ridiculously brittle. Also there was green stuff inside the pipe...

Both pipes that failed were cold main feeds probably installed mid seventies. There were no soldered joints in the pipework, it was all compression so no flux. Heating pipes of similar age show no degradation.

My theory is that something in the water has slowly eroded the copper over several decades. I'm replacing with plastic.

 

[kirkgas]

i remember having a lot of trouble with this years ago in Glasgow, when we turned off the water to fix a bit then turned on the water again it seems that the initial turning back on of the water washed all the cr@p of the inside of the pipe causing it to leak somewhere else, we had to bite the buttet and renew from top to bottom, as it is the only way to be sure you don't have a flood

 

[TicklyT]

Late '60s..... Hmmm..... Wasn't there a copper shortage about then?
Maybe the stuff was paper-thin in the first place, and maybe not the best grade of copper ever produced. So it might just be 40 odd years of fair wear and tear are beginning to show.

I would consider replacement rather than repair, as there's a fair chance the rest of the pipe run is in about the same state.

 

[jlacd]

As has been mentioned, its either electrolytic corrosion, or residue of flux, is the pipe a cold main??? are there one or two pipes side by side??? or does there seem to be any indication that another pipe was running along side??

Yep, pipe's a cold main. HW runs alongside it - 10cm gap between the two throughout the length of the run. No indication of anything else. My bet's on a DIY solder job, and pipe full of flux.

> using rubber-solution glue, glue a bandage of bicycle inner-tube round affected area
> apply a jubliee-clip over the rubber, ensuring it does not cut into rubber, nor touch copper pipe (so no electrolysis set up)

Well that's one way of DIYing it... or you could just replace the small section of pipe, with peace of mind it won't leak (if done correctly).

As I said - it's not a small section - it's 10 or 12 of these over approx 4m run. There would be more joins than pipe, if I went down that road.

 

[jlacd]

Cheers for all the replies guys. More info - house is a late 60's home-build (bodge), on the Costa del Clyde. Looks like I'll need to replace. Seems only to be on the horizontal runs - verticals look OK (although, to be fair, the leeks wouldn't pool, so would be harder to spot).

FKFKFKFKFKFKFK.

I'm never buying "new" again... this place is a minefield. Gimme stone, slate, lath 'n' plaster any day. If I ever have to see a double electric socket put into a punched-out drywall hole held in place with silicone again, I'll fkin jump off the Erskine Bridge.

 

[Softus]

have found copper pipes with pinhole leaks.

That's commonplace with copper.

What I'd like to know is....

1> Why has this happened?

Copper doesn't last forever. It either corrodes, or erodes, and then it leaks.

2> What can I do?

Cut out and discard all old pipework. Replace it with new copper tube or new plastic pipe.

I thought I could do this:
> turn off water to relieve pressure, and drain down
> *GENTLY* wire-wool affected spots, and clean with meths
> using rubber-solution glue, glue a bandage of bicycle inner-tube round affected area
> apply a jubliee-clip over the rubber, ensuring it does not cut into rubber, nor touch copper pipe (so no electrolysis set up)

You could do, but you'll regret it when it p*sses water everywhere while you're away on holiday.

Would this work?

Er, no.

Any other solutions.

Yes - replace it.

I'd *REALLY* rather not get into replacing it.

Oh. OK. In that case, no - there are no workable solutions at all.

If I don't - what's the long-term prognosis - is it just going to get worse and worse, so I end up with a soggy ceiling again!?!?

Yes.

I am SOOOOO sick of this place - everything I look at turns out to be a botched job or just plain ****.

Welcome to the joys of property ownership.

Cheer me up, someone!

Um, in 34 days the days will start getting longer, which means we're en route to summer!

 

[roguetrader]

do you have a dart board nearby?? stray darts could be the cause of your problems.

 

[Kes]

As I said - it's not a small section - it's 10 or 12 of these over approx 4m run. There would be more joins than pipe, if I went down that road.

Not really. Two compression couplers and one length of pipe. If you can't manage with 3 mt (as that's the common length) then go to a proper plumbers' merchants and cut 4 mt, or whatever you want, from a 6 mt length. Keep the spare 2 mt as a souvenir.

 

[ChrisR]

I've noticed bad lengths in the middle of CH systems where others are OK, so I think it stems from poor pipe. Your soft Glasgow water wouldn't help. It wouldn't be flux causeing a problem on the INside of a mains pipe - it gets flushed out!
I've also noticed it in linear patterns, which makes me think it's manufacture-originated too.

Impurities in the pipe set up mini electrolytinc cells which lead to pitting corrosion, which leads to pinholes.

 

[Softus]

Copper pipe is likely to be fine after 100 years.

And yet, as we all know, it won't.

 

[blondini]

Causes of corrosion in plumbing systems - http://www.fwr.org/copper.pdf

 

[jlacd]

Thanks for all your help guys - will replace, and add it to the 4-figure roof repair bill, Wifey's 40th, Christmas, and twins 5th b'day all happening in the next 8 weeks.

You'll find me walking the streets touting for trade down by Greenock docks next week. Do the "Eye Need" ads in Private Eye work?

 

[shambolic]

Have came accross this loads of times in glasgow it was due to poor quality copper pipe during the copper shortages. Wait till you get some truewell extruded stuff!!! Nothing for it but to change it. Had one a few years back and it was pitted al along it's length every few inches with wee black holes weeping water.

 

[jlacd]

Have came accross this loads of times in glasgow it was due to poor quality copper pipe during the copper shortages. Wait till you get some truewell extruded stuff!!! Nothing for it but to change it. Had one a few years back and it was pitted al along it's length every few inches with wee black holes weeping water.

Yep, that's the fella - want to see some more, for nostalgia sake?

 

[Peet]

Whilst reading up about Stainless steel in plumbing I came across this which mentions pinholing in copper in a wider study:
http://www.bssa.org.uk/cms/File/BSSA PLUMBING P.1-4.pdf

I'll copy the document's pertinent text below in case the original moves or disappears.....

USE IN SCOTTISH HOSPITALS
Stainless steel has been used for plumbing installations across the U.K., but has been of particular importance in Scottish hospitals. The following quotations from the Scottish Hospital Technical Note 2 Version 1 (SHTN) explain some of the reasons for the growing popularity of stainless steel
installations:
This SHTN addresses the problems experienced by the NHS in Scotland in consequence of the corrosion of copper pipework systems. Despite extensive research, the absolute cause of the corrosion is not yet understood, but enough is understood to allow the conclusion to be reached that copper pipework in Domestic Hot and Cold Water (DHCW) services in hospitals in many areas of Scotland, where the water is soft, and contains high levels of sediment, has a high propensity to failure¹.
The Technical Note elaborates this basic conclusion in more detail:
• Since 1983 it has become evident that corrosion of copper piping within DHCW services in many Scottish hospitals and other Healthcare Premises (HPs) is a serious problem.
• This corrosion, which takes the form of localised pitting or ‘pinhole’ attack to the wall of the piping, may be unique to institutional buildings, and with slight variations, has been found to be predominant in soft water regions throughout Scotland. Other countries in mainland Europe have experienced similar problem, with Northern Ireland and Wales recently identifying corrosion within HPs.
• Although this form of attack has not as yet resulted in a catastrophic form of failure, it does lead nevertheless to a severe shortening of a system’s useful life, with a noticeably growing incidence of repair work and disruption to the operation of a hospital as the extent of pipe failure and water leakage increases.
• Several Scottish hospitals which have suffered serious pipework corrosion have now been re-piped using alternative materials for the pipework system.
• The approved alternative materials are, at this time, the austenitic stainless steels, the polyvinyl-chloride (PVC) plastics, polybutylene and crosslinked polyethylene (PEX)².


Sources in the above document:
¹ Domestic hot and cold water systems for Scottish Healthcare Premises Scottish Hospital Technical Note 2, (Version 1), NHS Scotland, Property and Environment Forum, December 1999, p.7.
² ibid, pp.8 & 9