Riser Clamp Size

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by DougB, Sep 30, 2013.

  1. DougB

    DougB Member

    I want to cut out a section of cast iron waste pipe, and before doing so, install a riser clamp on the floor above.

    The pipe is 3 1/2" OD - I figure this is what they call 3" waste pipe?

    All I've been able to find on the net (and Grainger) are 3" riser clamps. What do you think?
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,815
    Location:
    New England
    I think, but do not know for certain, when they are referring to a 3" riser clamp, they're referencing the ID of the pipe...most of those I've seen are two parts that clamp around the pipe, and the OD has some leeway. Most drain pipe has about 1/4" walls, so 3.5" is about right for the OD.
  3. Terry

    Terry Administrator Staff Member

    Messages:
    14,780
    Location:
    Bothell, Washington
    It would be a 3" riser clamp
  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,270
    Location:
    Cave Creek, Arizona
    A 3" waste pipe would take a 3" pipe clamp.
  5. DougB

    DougB Member

    Thanks guys.
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