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Nipple(s) Length

DEfagan Member Posts: 1
I want to add a 1 ¼ X 1 ¼ X 1 ¼ Tee in the middle of a pipe that is 13” from 1 ¼” elbow to 1 ¼” union. The pipe that I’m going to replace is screwed into the elbow and the union and the distance between the two points that I want to add the Tee is 13”. What size nipple or nipples do I need to use to maintain the distance of 13” after installing the tee?
Thanks for any help.


  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 6,669
    Depends on the actual measurement of the tee. It is a trial and error thing. You also need to know how many threads are screwed into the elbow and union. Can you take the nipple out and go to a local supply house? They can take a tee off the shelf and a couple of nipples, screw them together and get close. I would also purchase the next 1/2" longer for both the nipples that make up the correct size. This allows for the way the nipples are threaded. some nipples take 4 threads to get tight to stop leaking, other may take up to 6 threads to get there. I don't know of a formula to get there. But others who do more steam fitting might know.

    Mr. Ed
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics
    EBEBRATT-Ed Member Posts: 14,455
    I calculated it that 2 6" nipples "should " be right. The 1 1/4 tee should be 3 1/2" face-face.

    I am assuming that your 13" measurement is face-face ....from the edge of the union to the edge of the elbow. I would also get a 5 1/2" nipple just in case. Your probably end up with the 5 1/2 and the 6
  • HomerJSmith
    HomerJSmith Member Posts: 2,303
    I have always calculated that a nipple would screw in to a hub at 3/8". The distance from hub to hub + 3/4" would be close enough for government work.
  • GW
    GW Member Posts: 4,616
    Most pros carry nipple trays; what your asking is more time consuming

    just go to the store and screw these things together and bring your tape measure. 

    Assuming you’re not going to bring wrenches into the store, there’s always a little bit of guessing. Buy the nipples you need. One of those nipples should be a half inch longer and a half inch shorter just for Murphy’s Law. Return the nipples you do not need.
    Gary Wilson
    Wilson Services, Inc
    Northampton, MA
    [email protected]
  • retiredguy
    retiredguy Member Posts: 836
    edited September 2022
    Before I retired I was sent to a work site for a boiler update. I would be replacing the 2" gas train as one of items on the "to do" list. The head engineer that laid out the job told me that I would be met in the am by a helper and that he would bring everything I would need. All I needed was to show up!. He had laid out the entire gas train from the gas drop to the burner and supplied a drawing showing every fitting that I would need. He supplied only those exact nipples he wanted and where they would be placed. Well, you guys know the result. About 1/2 hour on the job, I was calling that engineer to tell him the problem. He sent out another helper with a "nipple kit" and a pipe machine. I requested that he also come to the location so I could have him learn something not taught in engineering school. (Murphy's Law)
    EBEBRATT-Ed Member Posts: 14,455
    One problem is the schedule 40 pipe and nipples have less quality control and tolerances than in the past.

    Pipe a job with schedule 80 and you will see what I mean.

    I have done a lot of jobs by calculation. You always need to leave yourself an "out" Nipples and pipe don't always make in the amount the book says especially dealing with the off shore components