Solvent weld joints for waste pipe

[Roger Mills]

I shall shortly need to re-do the waste pipe from a bathroom (bath and basin - not toilet) and some of the joints are going to end up in a space which will become inaccessible thereafter. I therefore need to use solvent weld joints in this location because I can't risk push-fit joints leaking or coming apart.

Having not used solvent weld very much - the last time was over 30 years ago! - I can't remember how long it takes for a joint to become unmoveable. If I assemble a joint, and need to (say) rotate an elbow for alignment purposes, how long have I got before it becomes impossible?

If I use push-fit for all the accessible bits, what's the trick for joining push-fit and solvent weld pipes - because, AIUI, the pipe diameters are likely to be slightly different?

[Jim]

No time at all, basically. Best plan is to assemble it all dry, then mark the joint alignments with a pen or something before gluing it.

[Jim K]

use compression if push fit won't take the pipe?

Cheers Jim K

[Tim Watts]

First check if you are jointing ABS (most likely) or (m)uPVC (less likely with smaller pipes but possible). If in doubt, get a dual ABS/uPVC cement which is what I use (I was jointing 110 uPVC as well as

40/50mm ABS).

About 5-10 seconds! Full strength in a few hours.

Dry fit, then mark a line across both bits of every joint. When it's right, go back and cement them. Wipe the surfaces with meths/IPA/other solvent before applying cement. Sandpaper the old pipe first as that will be excessively cruddy compared to new stuff. Ensure any paint is removed.

The official way would be to use a universal compression fitting - but as that has some risk of coming apart (bugger all in reality, but as you are too worried to use pushfit...) you could slaver it up with Fernox LS-X (plumbers silicone) for extra confidence. However, if the pipes in question are a reasonable (not sloppy) fit in the solvent weld adaptor, weld them regardless provided the plastics are weldable (I *think* most pushfit is also ABS??).

I have had solvent fit from different manufactures either be tight or quite loose but in both cases, they welded OK (apply generous cement to both parts if sloppy).

Cheers

Tim

[The Wanderer]

Do make sure you get a solvent weld pipe, your bog-standard pipe from the sheds doesn't take solvent weld at all. It's also worth noting that you can get a gap-filling solvent paste as well as ordinary solvent weld.

[Tim Watts]

?

I've bought solvent weld ABS from B&Q - in fact they have a surprising range of fittings in T Wells.

I wonder if that is what mine is - it is a very heavily loaded cement, quite gooey and blobs of it set solid.