Seal Compression Cap?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by GoDillos, Jan 12, 2008.

  1. GoDillos

    GoDillos New Member

    Joined:
    Jul 26, 2005
    Location:
    California
    I am removing a sink and trying to cap off the copper supply line. I have easy access to where it branches off, and it uses a compression tee there. I think the cleanest thing would be to just undo it's branch from the compression fitting and put what I've seen called a "compression cap" on the threaded connection there.

    I understand that a a normal compression fitting uses the ferrule to seal. But, how do these end caps work when there's no pipe underneath them? Do I need to use tape or dope? Do I put a washer under there?

    Thanks
     
    Last edited: Jan 12, 2008
  2. hj

    hj Moderator & Master Plumber Staff Member

    Joined:
    Aug 31, 2004
    Occupation:
    Plumber
    Location:
    Cave Creek, Arizona
    cap

    They make compression caps that screw onto the tee, but their success rate at not leaking is not very good. Cutting a washer to fit inside may help it seal better.
     
  3. Sponsor

    Sponsor Paid Advertisement

     
  4. GoDillos

    GoDillos New Member

    Joined:
    Jul 26, 2005
    Location:
    California
    Thanks, what do you think about putting some pipe dope on there too?
     
  5. Furd

    Furd Engineer

    Joined:
    Jul 3, 2007
    Occupation:
    Retired energy systems engineer
    Location:
    Wet side of Washington State
    I tried using just the compression caps and they leaked. I cut some rubber discs (used an arch punch) and they sealed quite well.

    I do not recommend using pipe sealant on anything but tapered pipe threads.
     
  6. Redwood

    Redwood Master Plumber

    Joined:
    Dec 15, 2007
    Occupation:
    Service Plumber
    Location:
    Connecticut
    Last edited by a moderator: Mar 26, 2020
  7. SaidWhatWhen

    SaidWhatWhen New Member

    Joined:
    Mar 26, 2020
    Location:
    San Jose CA
    Thanks Terry. BTW, for others, the flat washer for 3/8 compression end cap is Size 0 or 17/32" which I bought at Ace Hardware. Danco mfg Stk #35063B.
     
Similar Threads: Seal Compression
Forum Title Date
Plumbing Forum, Professional & DIY Advice Cone Seal for 3/8" Soft Compression Fitting on Flexible Water Supply Aug 2, 2019
Plumbing Forum, Professional & DIY Advice Slight dishwasher leak at compression seal Jan 10, 2007
Plumbing Forum, Professional & DIY Advice No reason for sealant on PP kitchen p-trap, right? Sunday at 1:29 PM
Plumbing Forum, Professional & DIY Advice Crane Co. Stem # FB7673, Need Help Identifying Faucet for Seal Replacement Mar 11, 2020
Plumbing Forum, Professional & DIY Advice Sealing gap between laminate countertop and farmhouse sink Mar 2, 2020

Share This Page