Waste pipe couping

[Bratman91]

A kitchen sink 40mm waste pipe has cracked close to the point at which is disappears behind the cabinet rear wall. I have repaired this by cutting the pipe and joining the two ends with a compression fit coupler, However, the end that disappears behind the cabinet is close to a junction and will only insert into the coupling a short way.

It seems to be holding but I am concerned that it could too easily be pulled out from the coupler. Is it possible to buy coupling pipe slightly smaller in diameter than the existing pipe so that a short length could be pushed into both ends and fixed with solvent? Thus, the two ends would be bridged by a short section of slightly smaller pipe.

 

[moggridgeplumbing]

A bodge job you mean! No replace the pipe and sleep soundly.

 

[Bratman91]

Why would it be any more a bodge job compared with joining the two ends with a solvent-fixed coupling that fitted round the two ends rather than inside them? Replacing the pipe sounds simple but it is joined with a solvent-fixed coupling to a pipe that disappears behind the sink cabinet. To remove the pipe would be very difficult.

 

[Charnwood]

Why would it be any more a bodge job compared with joining the two ends with a solvent-fixed coupling that fitted round the two ends rather than inside them?

You'd need a pipe with an OD of roughly 37mm. Where would you get that?
Instead of using a compression joint, if as you say there's enough pipe near the junction to make a joint, use 2 solvent couplers and a short piece of pipe. A 'shallow' connection would be more secure in solvent weld than compression.

This is only feasible if it is a solvent weld system already fitted. You can't use solvent cement on push-fit pipe.

 

[Bratman91]

Why would it be any more a bodge job compared with joining the two ends with a solvent-fixed coupling that fitted round the two ends rather than inside them?

You'd need a pipe with an OD of roughly 37mm. Where would you get that?
Instead of using a compression joint, if as you say there's enough pipe near the junction to make a joint, use 2 solvent couplers and a short piece of pipe. A 'shallow' connection would be more secure in solvent weld than compression.

This is only feasible if it is a solvent weld system already fitted. You can't use solvent cement on push-fit pipe.

I hoped that couplings of 37mm would be a a standard item. Must talk to Dragons' Den about this gap in the market!

So, a solvent coupler seems to be the best bet but I don't understand why it should be two and a short piece of pipe. What I have now is two ends of the pipe with a gap of about half and inch between them. Don't these two ends simply push into each end of a single coupler? Sorry if this is a daft question but I want to understand the issue properly.

The pipe is actually part of a trap that has a push-fit connector at one end. However, it is fixed at the other end into a junction that is definitely not a push-fit and, as far as I can see, is solvent fixed. Does this mean that the use of a solvent connector is prevented?

 

[Charnwood]

you didn't say how big the crack was. You might just get away with the coupler.

Can you post a picture or two? Might help.

 

[Bratman91]

you didn't say how big the crack was. You might just get away with the coupler.

Can you post a picture or two? Might help.

The sink is in a tenants house that I can't get at easily but here's a sketch of the pipework showing the crack and, underneath, how I have at least temporarily stopped the leak by cutting through the pipe so that I can get a compression coupling around it.

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• Bratman91
• 8 Feb 2012
• 1

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[TicklyT]

An internal sleeve will reduce the bore of the waste, form a small dam holding a puddle of stagnant waste water and leave a shoulder as an ideal starting point for blockages to form.

Have you addressed the reason why the original pipe cracked? Just repairing the crack without establishing why it failed may just leave a pipe ready for a repeat performance.

 

[Bratman91]

An internal sleeve will reduce the bore of the waste, form a small dam holding a puddle of stagnant waste water and leave a shoulder as an ideal starting point for blockages to form.

Have you addressed the reason why the original pipe cracked? Just repairing the crack without establishing why it failed may just leave a pipe ready for a repeat performance.

That's a good point - I can see how the shoulder could act as a starting point for blockage.

I think the pipe cracked because it was being forced away from its natural resting point by washing machine and dishwasher hoses and by too many loose items being stored in its vicinity. I couldn't find any other reason for the crack occurring. I loosened off all the compression connections and then re-tightened them gradually one at a time while ensuring that none of the pipework was being stressed.