3/4” / 27mm Alkathene pipe

Discussion in 'Plumbers' Talk' started by Ponchoman1, Apr 2, 2024.

  1. Ponchoman1

    Ponchoman1 New Member

    So, I found a load of dodgey pipe work and a seized internal stop cock in this old house I purchased last year. I want to swop out the stop Cock but it’s seized onto the brass connector that fits on this black mains pipe, so what I need in case I destroy it all trying to get it apart is an imperial alkathene pipe connector threaded one end to take a new stop cock and compression fit the other to go on the incoming black mains pipe, can any one point me in the right direction to get the parts please?
    My vernier says OD of black mains pipe is 27 - 27.2 mm. I looked up the black pipe and it says 26.9mm so I guess mine is prob that?
    Picture attached

    Attached Files:

  2. BuildingMad

    BuildingMad Screwfix Select

    As well as the outside diameter size, the Alkathene is either Class 'C' or 'D' and this can only be determined from the internal diameter, so best to be prepared with adapters for both sizes.

    However, you may find the 'class' printed on the outside of the pipe, at intervals.

    Approximate Alkathene Pipe Sizes in mm

    Pipe……Class C ID………Class C OD…………Class D ID…………Class D OD

    3/4 inch….19.5 mm…………26.9 mm……………17.5 mm……………..26.9 mm

    You may need modern fittings with adapters for alkathene to complete your task.

    Give BES Plumbing a ring; their technical chap is very helpful.
  3. LearnMore

    LearnMore Active Member

    Have a look on the nut (if you can) on the bottom of the stopcock, see if there’s a size on it, looks like a 22mm one imo.
  4. WildCat

    WildCat Well-Known Member

    Herts P&D and LearnMore like this.
  5. BuildingMad

    BuildingMad Screwfix Select

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