Why does a pipe split?

[mrherb]

WITHOUT PREJUDICE

I think there was frost damage already, and the pipe was about to split. Not the installer's fault. A longitudinal tear is characteristic of frost damage, and it may have been stressed almost to failure at any time before.

He has already been kind enough to repair it for free, and it is not reasonable to expect him to repair other damage.

That is an interesting point - and just the kind of specific advice/experience I was after thank you!

WITHOUT PREJUDICE
He has already been kind enough to repair it for free, and it is not reasonable to expect him to repair other damage.

Some misunderstanding here - to clarify he specifically hasn't done anything for free - we paid him for all work done prior to the leak occurring but are just wondering whether he should be paid for repairs to the damaged pipe. We are paying for all other repairs/ will have to claim on our insurance (& take the resulting hit on our premiums).

 

[Onetap]

A longitudinal split is typical of frost damage. More specifically, it is typical of a failure due to over-pressurization because the hoop stress is double the axial stress in a thin cylinder under pressure. Look up thin cylinder theory if you fancy a bit of simple maths.

It could have been partially split at some point in the past when the building has been unoccupied, unheated and frozen, but you'd expect it to split at that time. Could it have split in the last cold winter if the water was off, but the pipes weren't drained? What could he have done to over-pressurize an existing pipe?

Pressure testing, possibly; it is easy to over-pressurize a hydraulic pressure test with a proper hand pump. Possibly soldering a sealed system, but I think that's unlikely since we're probably talking about 15 or 20 bar pressure. Maybe over-pressurization of the hot (?) water system due to no provision for expansion, but I'd expect the heater to split before the tubes. I'd check the safety devices, just to be safe.


Did he use a pressure test pump? Google for a picture of the common Rothenberger hand pump. Cowboys don't use them.

Alternatively, there may have been an existing unnoticed leak. I doubt that you'll be able to prove what happened and he is not liable unless you can. The only way you'd prove it was him is if there is similar bulging on a straight section of the new pipe he connected to the existing split pipe. I'd be inclined to think he's not guilty, at present.

 

[Agile]

Frost damage exerts considerable pressure radially because the longitudinal pressure is reduced by friction with the pipe in a longitudinal direction.

Having said that frost damage will usually push off a nearby compression fitting first before splitting the pipe.

A soldered joint is just as strong as the pipe itself.

Tony

 

[mysteryman]

This is is characteristic frost damage, quite possibility with small repeated straining of the pipe with successive freeze-ups. It always tears longitudinally because the radial stress is twice the endways stress, as stated above.

As a matter of interest, my first house had a mains cold water pressure of 11 bar or 165 psi and metric copper pipe was OK with that.

 

[gas_man_gaz]

Frost damage exerts considerable pressure radially because the longitudinal pressure is reduced by friction with the pipe in a longitudinal direction.

Having said that frost damage will usually push off a nearby compression fitting first before splitting the pipe.

A soldered joint is just as strong as the pipe itself.

Tony

never seen a correctly fitted compression fitting blown off pipe would split 1st

 

[kevinjc]

I go with previous frost damage and Plumber not to blame UNLESS you stated that when he does the work you Want ALL copper replaced with new.
For the many Bathrooms i have done i have never had a client ask for this,
Its very rare for me at least that a client will request something that will add to the cost of the job.
I generally replace just about all pipe work i can see anyway but am not committed to unless like i say they request it, and with most clients if they cant see it , it ain't there.
If you know what i mean.
generally, not Plumbers fault in my opinion.

 

[gasbanni]

Seen pipes split along their length with frost damage and also seen the same where it could not have possibily been due to frost !

In the hall of an apartment complex in the centre of the building which was mainly inhabited by wealthy old widows and was like the tropics.

Why not claim off of your buildings insurance ?