Announcement Announcement Module
Collapse
No announcement yet.
Back-to-Back threaded fittings, possible? Page Title Module
Move Remove Collapse
X
Conversation Detail Module
Collapse
  • Filter
  • Time
  • Show
Clear All
new posts

  • Back-to-Back threaded fittings, possible?

    Background information:

    I'm studying fire sprinkler system layout. I have little knowledge of piping fabrication limitations.


    Questions:

    1. For pipe sizes of 1/4" - 2" and type schedule 40 blk steel, is it possible for an average fabrication shop to create pipe lengths short enough to allow "back-to-back" threaded tee adjoining to another tee, or tee adjoining to an elbow? Can these short lengths be threaded?


    2. Is it costly if it can be done?


    3. If the pipe length or threads cannot be feasibly fabricated, can you have the fabrication shop weld the threaded fittings together on the side that they are touching other fittings, and leave the side for pipes open?


    4. Could someone please tell me the industry terminology for back-to-back fittings, so that I may better search for relevant information?


    Thank you very much for any help you may give.
    Last edited by lw1990; 02-04-2013, 02:35 PM.

  • #2
    Re: Back-to-Back threaded fittings, possible?

    Not completely sure what your asking but there are close nipples that when tightened up there is nearly no pipe exposed,

    http://en.wikipedia.org/wiki/Nipple_(plumbing)
    A "close nipple" has no untreated area; when screwed tightly between two female fittings, very little of the nipple

    remains exposed.

    usually to remove close nipple one needs a special internal nipple wrench if you do not want to damage the threads,


    normally nipples are cheaper to buy than try to make your self, there are nipple chucks that can hold the pipe sections for threading in a machine,

    I think you need to take a field trip down to a supply house or a good hardware store, or find a pipe suppler and get or down load a fittings catalog,



    Attached Files
    Last edited by BHD; 02-04-2013, 10:32 PM.
    Push sticks/blocks Save Fingers
    ~~~~~~~~~~~~~~~~~~~
    "The true measure of a man is how he treats someone who can do him absolutely no good."
    attributed to Samuel Johnson
    ~~~~~~~~~~~~~~~~~~~
    PUBLIC NOTICE: Due to recent budget cuts, the rising cost of electricity, gas, and oil...plus the current state of the economy............the light at the end of the tunnel, has been turned off.

    Comment


    • #3
      Re: Back-to-Back threaded fittings, possible?

      why use nipples when you can thread male versions of tees and 90s together?
      ~~

      ... it was plumbed by Ray Charles and his helper Stevie Wonder

      Comment


      • #4
        Re: Back-to-Back threaded fittings, possible?

        I use this tool! You can thread 2" long nipples, from 1/2" to 2" pipe sizes.
        Nipple Chucks / Adapters - RIDGID Professional Tools

        Comment


        • #5
          Re: Back-to-Back threaded fittings, possible?

          Originally posted by Plumber Punky View Post
          why use nipples when you can thread male versions of tees and 90s together?
          no field experience so not sure what is workable is my guess.

          don't think close nipples are approved for sprinkler work, but i'm not sure without looking it up, which is something a good designer would do before trusting the internet.
          ---------------
          Light is faster than sound. That's why some people seem really bright until you hear them speak.
          ---------------
          “If I had my life to live over again, I'd be a plumber.” - Albert Einstein
          ---------
          "Its a table saw.... Do you know where your fingers are?"
          ---------
          sigpic http://www.helmetstohardhats.com/

          Comment


          • #6
            Re: Back-to-Back threaded fittings, possible?

            I think the OP is referring to a cross mechanical tee.

            Comment


            • #7
              Re: Back-to-Back threaded fittings, possible?

              Originally posted by NYC LMP View Post
              I think the OP is referring to a cross mechanical tee.
              That's not how I read it at all. Sounds to me like he wants to join two tees by putting a close nipple between the bull or side outlet of each fitting, or a tee and a 90.
              In either case I stick by my belief that close nipple are just plain wrong unless absolutely necessary. There's no meat left after threading the whole length of pipe. And IF I had to use a close nipple I would use SCH 80 for a little added insurance. Many jobs I worked we could only use SCH 80 threaded nipples, no SCH 40 threaded nipples allowed by the spec.

              I won't even comment on the welding together of two threaded fittings. Use socket weld fittings and even there you need enough space between the two fitting bosses for your welds plus a small gap, so on a 1" 3000# SW you're probably looking at a minimum of 5/8" and preferably a 3/4" gap between the faces of both fittings. You could go closer yes but not without overlapping your welds.
              ---------------
              Light is faster than sound. That's why some people seem really bright until you hear them speak.
              ---------------
              “If I had my life to live over again, I'd be a plumber.” - Albert Einstein
              ---------
              "Its a table saw.... Do you know where your fingers are?"
              ---------
              sigpic http://www.helmetstohardhats.com/

              Comment


              • #8
                Re: Back-to-Back threaded fittings, possible?

                Why the h3!! would you want to fabricate anything when you can weld them up? I have never seen two tees that close together and going the same direction.
                AllurePlumbing.com
                • leak detection
                • drain cleaning
                • utility locating
                • conductor fault locating
                • and other specialties.

                Greensboro NC, Winston-Salem NC, High Point NC, Thomasville NC, Kernersville NC

                Comment


                • #9
                  Re: Back-to-Back threaded fittings, possible?

                  Close nipples are used extensively on fire sprinkler systems, and are approved, if threaded per standards. True close nipples vary in length (1" close nipple is 1-1/2" long, 2" is 2" long) The only time we see leaks, are when fittings contact each other, before joint is tight. If threaded, proper sealant is applied and tightened correctly, are great. We test at 200 psi for 2 hours. Didn't quite understand original question though. Usually we buy nipples, if they are shorter than 4" long, and thread them with a nipple chuck, if we need an oddball length nipple, like 2-3/8" etc.

                  Comment

                  Working...
                  X