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Thread: Quick Question

  1. #1
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    Default Quick Question

    How's it goin, new to the site and had a quick question. Is there a difference in diameter from an IPS thread to a NPT thread? Just have to do a quick repair and have an female Dura PVC IPS threaded elbow in ground, wondering if i could use a male Lasco NPT threaded tee to continue on, any insight on the difference between NPT and IPS would be great, thanks in advance.

  2. #2
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    Default Re: Quick Question

    the two are different thread patterns. the NPT is like for hoses and such and could be looked at as a rough thread. the IPT or Iron Pipe Thread is the common industry standard for copper threading, black iron pipe threading, brass fitting threading, etc.

    Now at lowe's or home depot, i think it is watts brand, that sells like a 100 different little baggies of fitting and such. this is the same place where you buy the different lengths of hoses and stuff. in the plumbing section.

    but they are different and won't match up without the adaptor.
    Process of elimination. Good luck.

  3. #3
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    Default Re: Quick Question

    IPS ( Iron Pipe Size) has nothing to do with threads just the size of the pipe. It specifies the inside diameter and wall thickness by rating.
    NPT (national Pipe Thread) is national standard specifications for pipe thread in the U.S.
    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  4. #4
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    Default Re: Quick Question

    Not unless your threaded elbow is FPT.

    tapered threads not the same as straight threads

    Pipe Size is the accepted industry designation and does not refer to either the inside or the outside diameter (ID or OD) of a pipe or a fitting.

    NPT: National Pipe Taper Thread
    A sealant compound or Teflon tape must be used for a leak-free seal.
    FPT: female (internal) National Pipe Taper threads
    MPT: male (external) National Pipe Taper threads
    NPTF: Dryseal American National Standard Taper Pipe Thread
    No sealant is needed for a seal.
    NPS: American Standard Straight Pipe Thread
    Used for mechanical joining -- holding a fitting in place. An O-ring or a metal seal is required.
    NPSF: Dryseal American National Standard Straight Pipe Thread

    Hose threads are completely different.

  5. #5
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    Default Re: Quick Question

    Last edited by canuk; 08-13-2008 at 10:22 PM.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  6. #6
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    Default Re: Quick Question

    I should have mentioned your threaded elbow might also be identified as FiPT, same thing as FPT.

  7. #7
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    Default Re: Quick Question

    Quote Originally Posted by Gray Watson View Post
    Pipe Size is the accepted industry designation and does not refer to either the inside or the outside diameter (ID or OD) of a pipe or a fitting.
    Actually that's not true, all pipe up to 12" is sized by it's ID whether the IPS (iron pipe size) or the NPS (nominal pipe size) is used. A " pipe has a " ID.
    Jack
    Last edited by JLMCDANIEL; 08-14-2008 at 12:00 AM.
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  8. #8
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    Default Re: Quick Question

    Without straying too far off topic ... the discussion relating to IPS and NPS is somewhat a moot point considering that in this case the topic relates to domestic water distribution which falls under the category of tubing.

    In this case the tubing size is the outside diameter ( OD ) regardless of the wall thickness.

    For example .... copper tubing that is Type L has a thicker wall than Type M ....which means the Type L has a smaller inside diameter ( ID ) than the Type M ..... but they both have the same OD.
    So ... 1/2 inch Type L or Type M tubing would be able to use the same fittings.
    "" an ounce of perception -- a pound of obscure "
    - Rush

  9. #9
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    Default Re: Quick Question

    Except the OP said an IPS threaded elbow which means it's an adapter to pipe and IPS is vertually the same as NPT size. And it's PVC which is pipe not tubing. A 1" PVC pipe is 1" ID.
    Jack
    Last edited by JLMCDANIEL; 08-14-2008 at 03:23 PM.
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  10. #10
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    Default Re: Quick Question

    Geez ... you're correct Jack.
    For some odd reason I thinking it was a water line ... disregard my babble
    "" an ounce of perception -- a pound of obscure "
    - Rush

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