Capping a live water line

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by drembedded, Jan 7, 2012.

  1. drembedded

    drembedded New Member

    Messages:
    3
    Location:
    Peoples Republik of California
    I need to cap an old 3/4" black pipe water supply line but there is no way to shut off the line. Why there isn't a shutoff valve is a whole other story!

    This supply line was the original water source to our house and we've since switched to a different source. The old line is already capped off but I need to remove 30 feet of this old line. The line was burried and is somewhat rusted.

    I thought about cutting back just before a union then unthreading the remaining stub from the union and putting in a valve or a plug/cap. My concern is that the pipe may be so rusty that this may not work and I'll be left with a free flowing line.

    As a backup, can I pinch the line? Is there a special pinching tool? I'm open to just about any ideas!

    Thanks.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,608
    Location:
    Cave Creek, Arizona
    WHY would you even consider leaving a "black steel water line" in an active state? The ONLY proper way to do it would be to disconnect it at the source, because it will ALWAYS continue to rust out and leak as long as there is water in the pipe.
  3. drembedded

    drembedded New Member

    Messages:
    3
    Location:
    Peoples Republik of California
    Was looking for help and not criticism :-( Agreed that there is the "proper way" but there is also the "I gotta get something done now way".

    But since your post asks "WHY", I'll let you know a bit more about our water situation. We're on a private water system which was put in by the original ranchers back in '49. For the mains in our system, they used surplus water line from WWII that was meant to be used to transfer fluids from a beachhead inland. Needless to say that wasn't the "proper way" to develop a water system. For the laterals they used black pipe and buried it without any protection like wrapping it. To make matters worse they really didn't keep good records about what was where and on whose land it was, nor where shutoff valves (is they even used any) were located. Sometimes I wish I lived an a newer housing development...

    So with that said, I'd entertain any ideas on how to resolve this issue with a short term solution :)

    Thanks.
  4. Smooky

    Smooky Member

    Messages:
    620
    Location:
    NC
    You can combine a compression fitting such as a dresser coupling with a valve. Then cut the water pipe off. Slide one end of the compression coupling onto the pipe, with the cut-off valve open. Tighten the compression coupling onto the pipe and then close the valve.
  5. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
  6. cacher_chick

    cacher_chick Test, Don't Guess!

    Messages:
    3,246
    Location:
    Land of Cheese
    Some plumbers have a device that will freeze the water in a section of pipe to prevent flow while the piping is being repaired.
  7. Smooky

    Smooky Member

    Messages:
    620
    Location:
    NC
    I have also seen ford pack joint couplings used for this type of repair. (Google it.) They can be combined with a shutoff valve easily. These couplings are often used to connect water meters to the city supply.
  8. drembedded

    drembedded New Member

    Messages:
    3
    Location:
    Peoples Republik of California
    Smooky, the Ford Pack Joint Couplings looks like the easiest solution. My only concern would be whether the compression fitting would be able to seat well against the corroded pipe.

    Jimbo, that Jormer Valve looks sweet but it looks like it has expensive!

    cacher_chick: freezing the line would make putting in the compression fitting much easier. Wonder if Home Depot rents those ;-)
    Last edited by a moderator: Jan 8, 2012
  9. Gary Swart

    Gary Swart In the Trades

    Messages:
    7,347
    Location:
    Yakima WA
    I sure hope you realize that whatever you do now is just a stop-gap fix. Sooner or later, add more likely sooner, you will have to get rid of that black iron and get your system up to par.
  10. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,608
    Location:
    Cave Creek, Arizona
    The realistic problem with what you want to do, is that ANY black steel pipe will be heavily corroded on its exterior. The rust will make it BIGGER than a standard pipe, and when the rust is chipped off it will be both smaller and pitted, making ANY compression connection IFFY as far as not leaking, and also making it impossible to rethread the cut off portion. There might be a way to accomplish the task, but we would have to see the pipe's condition first.
  11. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    The JOMAR will set you back a c-note and a half, and even that may have difficulty on a heavily pitted pipe.

    This may a case where you have been given the best possible advice right from the get-go, but you will persist in trying to find a "work around" no matter what the cost or consequences.
  12. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    I hate to tell you guys, but if its from 1946 and mostly holding water, its DUCTILE IRON. Which outlasts any galvanized.
  13. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,608
    Location:
    Cave Creek, Arizona
    "3/4 inch" Ductile iron? In '46 we WERE using "regular" steel pipe, black AND galvanized. Black ductile iron will outlast some galvanized but it is NOT an "eternal" metal. Acually there is NO WAY to tell what can be done with it until it is exposed to see its condition.
  14. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    If its black pipe you can shut it off with a block of iron and a sledgehammer and fold it over. Have a nice shower. Ductile is unusual in 3/4" but you never know what went on with army surplus after the war. Ductile would likely break with a hammer.
  15. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,608
    Location:
    Cave Creek, Arizona
    "Ductile" means it is "malleable" and would NOT break. Most "army construction" jobs, especially housing, were designed to last 10 years, or until the war was over, so they did NOT worry about using materials with any kind of longevity. It was all "quick and dirty".
  16. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Actually, ductile iron is closer to cast iron in relation to black pipe and retains some brittle qualities. I know, I have cracked larger sizes.

    http://en.wikipedia.org/wiki/Ductile_iron_pipe

    Some of that quick and dirty work during the war had standards far above the debri hitting our shores now.

    Malleable iron is pretty much reserved for castings that are to be machined. It indeed can take hammer blows.
    Last edited: Jan 11, 2012
  17. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    21,990
    Location:
    New England
    Bottom line...iron rusts and will not last forever when used as this situation has it installed. Anything you do with it is suspect with the age and current condition of it. You'd be far better off trying to decommission it or cap it off way back at a source that can be monitored more easily. Anything you do with it somewhere in the middle is risky. It's one of those pay me now or pay me later situations...
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