15mm copper pipe outer diameter compared to plastic

Discussion in 'Plumbers' Talk' started by willow5, Sep 17, 2013.

  1. willow5

    willow5 New Member

    Hi all -

    As the cold weather is setting in, my pipe burst. Unfortunately it is buried in the wall so rather than trying to repair it and cause a lot of disruption, I was hoping that I could try to remove it carefully and replace it with 15mm of plastic pipe. Please could someone confirm whether this is feasible and confirm the difference in outer diameters between copper and plastic?

    Many thanks
  2. Dave does Gas

    Dave does Gas Well-Known Member

    The tube itself is of a similar if not the same size, however its the fittings that may be the problem
  3. Water Systems

    Water Systems New Member

    Outside diameter is the same.  Copper pipe can go right into plastic fittings. Do not mix fittings and pipe of differing makes.
  4. tom.plum

    tom.plum Screwfix Select

    as others have said, the external dia of plastic is the same as copper, but the internal size varies,and this is where people get caught out, because the inserts vary as well, If you force a speedfit insert into a polypipe fitting, you will expand the pipe giving it a slightly bigger external size, this will cause the fitting to be tight going on and won't be able to expand with the heat, that fitting will fail sometime very soon, :(
  5. It's not cold enough yet & if it froze once it'll freeze again, both are same size, copper is ok for plastic fittings too, use inserts with plastic, cut with cutters not saw.
    if the pipe expands then the fitting expands
    its called 15mm for a reason, if it was different e.g 2 mm bigger it would be called 17mm

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