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How tight is too tight? 1.5\" & 2\" black steel pipe and fittings

bill_97 Member Posts: 172
is all we use for 2 inch . We seal the thread just like you described . There's no need to go all Hercules on the fittings . We tighten them enough to the point where you could get 2 more full turns if you needed to . Finding out where that point is takes some practice though . And don't worry about the fitting breaking . When steam hits that joint for the first time it'll actually loosen the fitting somewhat . Good luck with the project .


  • Peter Zelchenko
    Peter Zelchenko Member Posts: 21
    How tight is too tight? 1.5\" & 2\" black steel and fittings

    Hi, if intalling black steel pipe and fittings (Either 1.5" or 2"), how tight should I make them. Of course I ask now that the entire job is complete.....

    I have not fired the boiler (Steam gas fired Weil McClain), yet but hoping for no leaks. I put on 2-3 winds of teflon tape then rectoseal #5 pipe dope (just enough so after it is tightening there is a very small ring of excess where the pipe meets the fitting).

    I am no weakling but no hercules either. I have been using an 18" pipe wrench and tightening about as tight as I can make it.....If I did not think the pipe of fitting would make it one last complete turn, I did not take the chance.

    Now I am nerveous that I may have overtightened. If I did could all the fitting break on me when the pipe expands under the full temp of the steam when fired up? Thanks so much.
  • Paul Pollets
    Paul Pollets Member Posts: 3,656

    The fitting is tight when the last 3 or 4 threads of the exposed male end are visible. This also depends if you're threading pipe, and make the threads the correct length. Overtightening can split a fitting, undertightening causes leaks. Hoipefully, you've used steam fittings, rather than black malleable fittings. if not, it's difficult to remove the black mall. fittings down the road.

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  • bob young
    bob young Member Posts: 2,177
    pipe torque

    for 2 " pipe a 24 " wrench is the wrench of choice. the fittings may not be as tight as you presume. a do -it-yourselfer should check these things before you start into uncharted waters. hope for the best, rectorseal can be a big plus.
  • MIke_Jonas
    MIke_Jonas Member Posts: 209
    Thank you, Bob

    Here I am thinking I am a girlie-man because I use an 18" wrench on 1", 24" on 1 1/2", 36" on 2". I got a 48", too.

    All aluminum Ridgids, too. Not because I have small arms or anything, you know, just easier to carry in the truck.

    You made me feel better about m'self, Bob. Thanks.
  • bob young
    bob young Member Posts: 2,177

  • steveex
    steveex Member Posts: 95

    Forget about making them to tight, with the 18" you might not have made them tight enough.
  • Rich Kontny_3
    Rich Kontny_3 Member Posts: 562

    Paul's advice is the best I have seen here as wrench size does not factor in installers strength. We forever used the 3-4 threads showing rule. You of course have to periodically check that you are cutting proper thread depth.

    After almost 40 years of being part of the pipe wars I can assure you that back in the late 60s and early 70s we did a great deal of threaded work. The largest threaded I ever assembled was 10" galvanized for a storm drainaage system for a college fine arts center. This particular piping had the old "Durham" process fittings that had pitch engineered in the female threads for pitch. All the piping was done at a pipe fabricator and we installed using large chain type wrenches with 1'0 ft try pieces for alignment.

    This was very labor intensive work and each caught thread was a small triumph. We always used the old "Expando" pipe compound as it was very reliable when mixed and applied properly.

    I also did a great deal of wet heating work Hydronics and steam and everything there 2 1/2 and over was almost always required to be welded. Some of my fondest memories of the Dead Men fitters and weldors I worked with was their expertise and pride in workmanship.

    We did do steam plant and paper mill work with up to 12" galvanizd but that was always the threaded flange system
    where everyhing was cut and thread at a pre-fab shop. We ended up with just a few field pieces that we field measured and then assembled.

    Maybe more info then you needed but I have been off the site for a while and quite frankly missed you guys!

  • Peter Zelchenko
    Peter Zelchenko Member Posts: 21
    Fittings too tight.....time will tell

    Definalty not too much info Rich....always nice to hear stories of the Dead Men.

    So it sounds like I may be ok or they could be slightly looser than I would like.....rectorseal may play a big factor in leakage or not. I have to pipe the relief copper tonight, then tsp the system, flush clean and fire her up for the first time after all this work. Time will tell if I have a leak.

    Thanks to everyone who replied on this one. I have to say I have a ton of respect for those who do this for a living. While it may not be my full time job, I take a lot of pride in doing quality work that will last and last. I crack my wife up with how fascinated I am with steam....I love reading and re-reading Dan's books, which of course bore the heck out of her. All the reading/diagrams/calculations take me back to my mechanical engineering days.
  • oil-2-4-6-gas
    oil-2-4-6-gas Member Posts: 641

    if you used black maleable fittings you will not crack them, i have had helpers run threads all the way in on 90's threaded on the rigid 300 and they hadn't cracked it ,,, with the size pipe wrench you have you did not overtighten and typically the 3 thread showing works fine --honestly even the cast fittings with that size wrench you would NOT be able to crack the fittings without ReAlly straining
  • ScottMP
    ScottMP Member Posts: 5,884
    tight is tight

    When I was an apprentice I asked the same question " how tight should this be ? ".

    The answer I got back was " Tight is tight ! " . Man was I ticked off. What the Heck is that supposed to mean !! As I've gotten older and been in the pipe trades oh these many years, I now know. Tight is tight. Its a feel and no thread counting or wrench per pipe size will do. The way pipe threads are now adays and the poor quality pipe you never know how far the threads will bury in.

    The joint must be firm but not over done. Can't be loose enough to swing unless its a three foot lenght.

    Tight is tight.


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