Will silicone sealant make a good seal on PVCu soil pipe?

[GRC]

Current project had me swapping position of WC & bidet around, and fabricating new section of soil pipe to accommodate them.

As the existing pipe was solidly solvent welded with no free play, I took the hacksaw to it to remove a section, and in went (from drain end to vent end); 32mm boss for the bidet, solvent welded onto a stub of pipe, connected to ; 45 degree branch for the WC, then a section of straight pipe, connecting to another stub of pipe. As there was no free play, I connected the 2 pipes together with a coupler, cut lengthwise so's I could wrap it around the pipes, since I couldn't move the pipes to insert them lengthwise into the coupler.

It seems I didn't apply enough solvent cement to the coupler, as it was weeping a little when tested. I've thrown more solvent cement around the join, and will test again tomorrow once it's cured, but (to get to the question)

Any thoughts on how suitable silicone sealant would have been to treat the situation? I've put a wee dab of the stuff on a non-jointed section of the pipe, and I'll see if it's taken tomorrow, but has anyone out there used silicone on PVCu as an emergency measure or otherwise?

Regards, Graham

 

[ArtfulBodger]

I seen it done but I've never seen it work! mind you I have never seen a failed solvent weld before

 

[dmikem]

silicone will not fix a leak on plastic pipework!

 

[ChrisR]

What you should be using is a SLIP COUPLING, with rubber seals so things can move.
If you buy a standard solvent coupler for example. you knock out the centre stop an add the rubber seals. Lube well with silicone grease or spray, slide completely onto pipe then back half coupling's length. You can put the rubber seal on just one end of a fitting if you want.
Pipe clips go on the fitting, not the pipe, so the movement is at the top of the pipe length inside the fitting. You'll often see it done wrongly.
A vertical slip coupling won't support anything for long, but if the upper section is solvent and supported from above and the s-c is suppported, the pipe's botttom end can move

 

[GRC]

Slip coupling sounds as though one section of pipe would need to be swung fully to the side to allow the coupling to be put on the other; but there wasn't enough free play in either side to move them this far.

Got any web links to slip coupling illustrations etc? My local merchant had plenty of the pipe and solid fittings but claimed not to be able to supply any flexible fittings for the stuff. Didn't have time to tour all the merchants in the area.....

Regards, Graham

 

[GRC]

There must be something out there that can be wrapped around the solid coupler that I've used which will provide a seal..... some kind of mastic, amalgamating tape, etc..... suggestions?

The only appliance that's upstream of this join is the washbasin; the WC bidet and bath are all downstream.

Regards, Graham

 

[doitall]

if there's no movement either way you simple cut a length of pipe out push a slip coupling on both end fit pipe back in middle and slide both sockets over the joints

 

[kevplumb]

jeez
havent had a slip coupling for years
must be my age