Advice on old Osma soil pipe boss

[sparkybob]

Trying to connect up new 40mm waste into the old soil stack (which would be an absolute pain to remove), it's all Osma pipe, from the 70s.

Pulled out the old waste from the boss and discovered the seal is pretty knackered, hardened and cracked everywhere (red coloured seal in the photo).

Inside the boss is actually a black moulding, think you can just make it out from the photo (so even though the rest of the boss spigot is grey pvc, it's lined with a black plastic moulding). Do you think I could solvent weld the new 40mm pipe in place using gap filling cement?

The 40mm solvent wel pipe fits in fairly snug.

Needs a good clean up first obviously 😁

Many thanks
Rob

 

[ShaunCorbs]

There should be a code on the outside of the boss eg osma xxxxxx

 

[sparkybob]

For

There should be a code on the outside of the boss eg osma xxxxxx

The code on the snap fit cap of the 40mm boss was "Osma Z119" which doesn't bring up anything. Unfortunately its boxed in pretty well so couldn't see anything obvious on the socket itself, will try and check again.

 

[ShaunCorbs]

Could you measure the inside dia of the hole ?

 

[sparkybob]

Could you measure the inside dia of the hole ?

I will do yes, I reckon about 44 or 45mm though based on how much wiggle there is with a 40mm solvent weld pipe in it.

 

[ShaunCorbs]

Have you tried a 40mm coupling in it ?

 

[sparkybob]

Have you tried a 40mm coupling in it ?

No I haven't actually, I'll have a go tomorrow see what it fits like.

 

[Timmy D]

If the coupling does fit well, you might be able to get a better fit by expanding/creating a socket on the end of some pipe.

Get an off cut (10” or so) of 40mm and chamfer the edge (OC)

Get the pipe you’re creating a socket on (SP).

Stand up a blow torch and lock flame on.

Rotate the SP while moving in and out of the flame. Be careful not to burn/char it.

When softened, use the OC and push it at an angle into the open now softened end of the SP while rotating both. You’ll gently form a socket.

You may need to heat the pipe a couple of times.

If it’s slightly too large, once formed, heat it one more time and rotate it in to the boss for a perfectly sized connection.

 

[sparkybob]

If the coupling does fit well, you might be able to get a better fit by expanding/creating a socket on the end of some pipe.

Get an off cut (10” or so) of 40mm and chamfer the edge (OC)

Get the pipe you’re creating a socket on (SP).

Stand up a blow torch and lock flame on.

Rotate the SP while moving in and out of the flame. Be careful not to burn/char it.

When softened, use the OC and push it at an angle into the open now softened end of the SP while rotating both. You’ll gently form a socket.

You may need to heat the pipe a couple of times.

If it’s slightly too large, once formed, heat it one more time and rotate it in to the boss for a perfectly sized connection.

Timmy thanks for this advice, but would you then solvent weld the socket into the boss? Is there any reason I couldn't just solvent weld a 40mm coupler in directly if it's a good fit?
A normal 40mm solvent weld pipe fits fairly snug (with 1 or 2mm wiggle room) so was hoping that's close enough to use a gap filling solvent weld.
Cheers

 

[ShaunCorbs]

Yes should be if it’s a mm and use gap fill cement

 

[Timmy D]

Timmy thanks for this advice, but would you then solvent weld the socket into the boss? Is there any reason I couldn't just solvent weld a 40mm coupler in directly if it's a good fit?
A normal 40mm solvent weld pipe fits fairly snug (with 1 or 2mm wiggle room) so was hoping that's close enough to use a gap filling solvent weld.
Cheers

If the coupling fits, then no need for what I suggest.

You just want to get as good a fit as possible. Heavy bonded solvent weld will only take up so much space.

If the coupling doesn’t fit, rather than do what I’ve said, it might be easier to sand the outside of the coupling. Just giving you options.

If the fitting/boss is pvc, solvent weld will be fine.