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Thread: Whoa

  1. #1
    DIY Member chipshot's Avatar
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    Default Whoa

    I read on here somwhere that when using the thread tape for fittings that you need to hand tighten and then use a wrench to turn a couple more time. Well I did that and ended up actually twisting the copper tub spout into a spiral. At least I did a good job sweating the threaded apapter on becuase that held quite well.

  2. #2
    DIY Senior Member Mike Swearingen's Avatar
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    Default

    Actually, it would be an addtional quarter-turn on some things, but I only hand-tighten a tub spout on and just use enough teflon tape to get it right.
    Sounds like you need to re-sweat a new fitting.
    Good Luck!
    Mike

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Default tighten

    There are no "hard and fast" rules. You have to use a bit of common sense to know when the fitting, or in this case the spout, feels tight enough and that another turn would not be a good idea.

  4. #4
    Plumber jimbo's Avatar
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    For 1/2" NPT, the specified total engagement is .534", consisting of .320" (4 turns) by hand and .214" ( 3 turns ) by wrench. Then it gets tricky: ANSI in their spec acknowledges that in practical field situations, threads are often cut to a shorter total length than specified. Hence the engagement length and # of turns go out the window. Then, when using teflon tape, the reduced friction may allow hand tightening beyond the "spec". In steel pipe, overtightening is usually not harmful. With plastic pipe, overtightening usually destroys the threads and causes leaks. Plastic pipe manufacturers specify 1/2 to 1 turn MAX beyond hand tight. In your case, wrench tightening beyond limits, the "weak link" was the copper tube itself.

    This is one of those cases where a "feel" for the job is developed with experience.

  5. #5
    DIY Member chipshot's Avatar
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    I'm getting alot of practice sweating copper thats for sure. I've learned alot in the last day doing just about everything wrong. Today I get to re-do it all correctly.

  6. #6
    DIY Senior Member captwally's Avatar
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    Default

    Adding to HJ's and Jimbo's responses... Jeez, Jimbo, I think I remember those questions from the exam 20 years ago! Two threads visible on an 1-1/2" galvanized fitting..? But in reality, it is true: You have just got to get a feel for when a threaded fitting is tight enough. Not too loose and definitely not too tight.

    Then you have to consider the materials you are threading together. My mentor years ago told me to ask myself the "soft or hard" question. If you are threading a softer material into a harder material, IE PVC into a cast iron pump, vice versa or soft brass into steel... You have more forgiveness as the softer material conforms to the harder as you tighten it. When you are threading equally hard materials such as galvanized to galvanized, he taught me to use both teflon tape and pipe dope. Seems to work... I've never had a leak. But the bottom line is as the guys have stated. You just have to get the feel for when it is good and solidly tight. Not tightened until the fittings scream.

    One more thing- don't buy pipe dope at Home Depot or Lowes. Let your wife buy wallpaper there. They don't know a good pipe dope from a good spray paint. Buy some good stuff from the closest Plumbing Supply House. EZthreadSeal or "The Green Stuff..."
    Measure Twice, Cut Once
    Wally

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