Solvent waste/compression fitting?

Discussion in 'Plumbers' Talk' started by PHILPH, May 23, 2019.


    PHILPH Member

    I’ve discovered another problem fitting a vanity unit with the waste piping.

    I have to alter it slightly to move the waste pipe closer to the wall where the unit will sit.

    After lifting a few boards to expose things there is a T piece and 1 end has compression connector with a little bit of pipe going into the T and coming out it has been solvent welded?

    After reading up on it the thickness of pipe between solvent and weld differs?

    The welded end goes into the main junction outside.

    Any ideas please on the way forward on what to and what to use as I obviously want to avoid leaks.

    Can I mix both types of pipe and fittings?

  2. KIAB

    KIAB Super Member


    PHILPH Member

    Thanks for that however if I wanted to replace that T piece, I need to get a Mcalpine T or is it specificly a “Multifit” I need?

    Could I ask another question related to this.

    It,s currently a 40mm T piece, however I need a 32mm to come out the top end to accept the pipe from the trap therefore how do I get round this?.

    Can you buy a 40mm T with a 32mm outlet?

    Also can you get these items from Screwfix?

    You can guess I don’t do this type of work very often!
  4. DIYDave.

    DIYDave. Screwfix Select

    Not sure I fully understand what you've got ?

    A 40mm compression T to which you want to run 32mm waste pipe ?

    If YES.......

    Solvent weld reducer,

    Solvent weld coupler 40mm

    Solvent weld cement / pipe glue / reducer into coupling. Glue Short length of 40mm pipe into coupling and connect to 40mm compression fitting. Glue 32mm pipe into reducer

    PS. T St sell them both singularly :)
    Last edited: May 23, 2019

    PHILPH Member


    What is there at the moment is the waste pipe from the bath by a compressed fitting into the 40mm T fitting (this is a solvent weld T fitting) and goes through the other side of the T which is a solvent weld.

    The waste from the sink goes into the T ind this is solvent welded, however whoever done this has sqeesed some silicone or something as this sink waste pipe is 32mm and the T piece is a 40mm.

    I think it's abit of a bodged job left from the previous owner.

    Thanks Phil
  6. DIYDave.

    DIYDave. Screwfix Select

    Well .........if a 32mm pipe has been siliconed into a 40mm fitting ..... nothing to think about here ...... it’s a bodge for sure

    May not have leaked for the last 20 years (lucky) but it’s a bodge

    Rip out and replace and do it properly - nothing to think about mate :)

    PHILPH Member

    Thanks Dave,

    Already ordered those few bits you mentoned earlier.

  8. DIYDave.

    DIYDave. Screwfix Select

    Just test fit pipes and fittings before gluing into place

    Cut pipe ends nice and square, a simple wooden or plastic mitre box and fine tooth saw works well, (not worth buying a plastic pipe cutter) remove burrs and plastic dust before gluing

    Hope all goes well

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