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Measuring threaded steam pipe, and replacing it

I'm trying to determine the correct measurement for a replacement steam pipe. It's a single pipe system, a return or condensate pipe, it's 11-1/2 inches long (edge of elbow to edge of T). My local hardware store will cut and thread for me. I need to try and get the correct additional thread length for the pipe. The pipe is below the water level of the boiler. I assume I will have to turn the boiler off, drain it and after the repair, refill the boiler using using the automatic refill on manual.


  • JUGHNEJUGHNE Posts: 4,360Member
    Do you have a union close? If the tee and 90 are fixed in place they may not unscrew from anything they are connected to.

    You might consider 2 nipples with a union between the fittings.
    A picture would tell a lot.
  • STEVEusaPASTEVEusaPA Posts: 2,025Member
    Also if it's a wet return, you are either going to do some damage involving more pipe replacement, or have other sections of pipe about to fail (if that was what happened). So keep that in mind as you may open up an ugly can of worms where the sum of replacing all these little pieces ends up being way more than replacing complete runs. Plus with replacement you can put in a few 'extras' that will allow you to flush those returns out quickly and easily.
  • oldsteamsystemoldsteamsystem Posts: 11Member
    This is the piece of pipe. I want to replace from the elbow at the bottom of the frame to the T at the top.

  • gerry gillgerry gill Posts: 2,794Member
    This job should be handled by a pro. I can already say it is likely to expand in scope.

    Serving Cleveland's eastern suburbs from Cleveland Heights down to Cuyahoga Falls.

  • EBEBRATT-EdEBEBRATT-Ed Posts: 3,942Member
    If you want to try it yourself I usually allow 5/8" on each end for the threads to enter the fitting. Your going to have to take it apart back to the union.

    @gerry gill is giving good advise as he said this should probably be handled by a professional. If that pipe is shot you may be replacing others
  • oldsteamsystemoldsteamsystem Posts: 11Member
    Thanks, I was already aware that it would have to be taken back to the union. The situation I find myself in, Three professionals did not complete the work properly, including a new boiler four years ago. All the pipes in this area should have been replaced and weren't. A Professional last winter who worked on the left-hand assembly with the now corroded elbow, said we should hope the right hand pipe won't burst, and left it at that. I haven't the money to call any more pros to do this job. And I'm aware things will go sideways, they usually do. My options are limited, my income involve a disability pension.
  • Jamie HallJamie Hall Posts: 8,232Member
    Is the piece you are keen on replacing the one with what looks like black tape around it? If so, it's not the only piece that should be replaced while you are at it. That lousy looking elbow which looks as though it goes out of the picture to the left (to copper?) should go too. In fact, I would replace every pipe and fitting in the picture, if I were to do anything. You'll be much happier.

    Unless there is a union on the vertical pipe out of the picture to the top, though, it's going to be sawzall time.

    When you do replace, do add unions -- they make life much simpler in the long run.

    I'm thinking that this whole thing is actually the Hartford loop for the boiler. If it is, replace it with the dimensions as close to exactly the same as at present as you can.

    And yes, you will have to drain down the boiler to do the job, and then refill it.

    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England.

    Hoffman Equipped System (all original except boiler), Weil-Mclain 580, 2.75 gph Carlin, Vapourstat 0.5 -- 6.0 ounces per square inch
  • MilanDMilanD Posts: 1,105Member
    Take good pictures before starting and measure everything. Get a can of pb blaster or kroil and presoak threads before backing them out. Trick will be lining up all the connections so get a few nipples that are 1/4 off in length from each other. For a tight connection, pipe needs to thread into the fitting good 7-8 threads. If replacing also that elbow, it may need a union there, given sawsall doesn't bust up the brass to iron connection. Cut carefully there.

    Also, make sure you have good 2 pipe wrenches and 3 points of contact on pipes and fittings to prevent egging or breaking off at that tee, as that will require it too be replaced. Good luck!
  • oldsteamsystemoldsteamsystem Posts: 11Member
    Jamie Hall, Milan D Messages received, thank you for the advice, will act upon it.
    Not sure if you are comfortable working with copper. If you are, you might want to consider replacing with copper.
  • KahooliKahooli Posts: 112Member
    Um. It looks like your hartford connection is above the nominal water line. I could be wrong from how the pictures are taken. But it looks like that. They're usually supposed to be X" below the nominal water line (dictated in system manual).
  • oldsteamsystemoldsteamsystem Posts: 11Member
    know nothing about working with copper. I research weather the hartford loop is above the water line. if so what is the solution , lower the assembly?
  • oldsteamsystemoldsteamsystem Posts: 11Member
    Thank you Kahooli the top of loop (elbow) is at or just below the water line according to the instillation manual if this is a parallel flow (mine seems to be for a hartford loop). It should be at least 2in below the boiler waterline according to the manual. So what do I do, lengthen some pipes, and shorrten others to make this work out.
  • New England SteamWorksNew England SteamWorks Posts: 1,040Member
    Thread make-up ("additional thread length"):
    For 1" through 1-1/2" pipe add 1-3/8". For 2" add 1-1/2"
    Serving Rhode Island & Eastern Massachusetts
    Old Houses & Steam Heat Our Specialty
  • oldsteamsystemoldsteamsystem Posts: 11Member
    Thank you, have got a daughter with good construction skills coming in a few days. Used to live in lil' Rhody, now in PA. Will try to add a union, 1-1/2 pipe could you share the calculation for that?
  • New England SteamWorksNew England SteamWorks Posts: 1,040Member
    1", 1-1/4", and 1-1/2" pipe all have a make up of 1-3/8".
    Serving Rhode Island & Eastern Massachusetts
    Old Houses & Steam Heat Our Specialty
  • JUGHNEJUGHNE Posts: 4,360Member
    If I have a section of pipe to replace that is several feet long and need to add a union, I try to make my life simple by getting a pipe that is within 4-5" of the next fitting. Then install the long pipe with union attached and use that 4" or so nipple. Easier to measure for.
    I leave a few threads showing on the pipe at each end so if it has to be a little shorter to match the standard nipple length then that section will get tightened a little more than necessary.

    It comes out looking like it had a plan. I also occasionally do this with a coupling/nipple if building between two points that can have one end swivel, as in a 90.
    But then I have nipple trays with all the sizes up to 6". Even so a homeowner could buy 3-3 1/2-4" nipples to avoid trips to the store.
  • oldsteamsystemoldsteamsystem Posts: 11Member
    thanks new england, thanks jughne
  • oldsteamsystemoldsteamsystem Posts: 11Member
    My daughter came over. WE took out all the corroded pipe resized pipes to place the top of the Hartford loop a little over two inches below the boiler water line. We have tested the system and have no leaks. Thank you each and everyone.
  • rick in Alaskarick in Alaska Posts: 711Member
    Did your daughter do the work, or help?
    Either way, it sounds pretty cool.
  • oldsteamsystemoldsteamsystem Posts: 11Member
    Daughter took the physical lead, she is very good. I supplied the technical, and somewhat shaky, expertise. She works in television and film production in New York City. She builds sets, does prop design and construction, she a dynamo at all she does. She delayed coming by three days, she had received an emergency call to a show in upstate New York.
  • oldsteamsystemoldsteamsystem Posts: 11Member
    One last thing: last winter, repair pro used copper pipe on the wet return as part part the Hartford Loop (left side of first picture above) , should I get it out of the system since the rest is either black steel or even some very old real cast iron
  • MilanDMilanD Posts: 1,105Member
    I wouldn't worry about it. As long as the corrosion between dissimmilar materials is not progressing, likely at that transition of 2 materials, you are fine. Just keep an eye on it. There is a post here on the wall of a guy running a hidden in the wall wet return in 1" copper, with many turns to accommodate hiding it in his finished basement. Thing of beauty.
  • j aj a Posts: 1,795Member
    If you don't have time or necessary skills and tools,as well as care how it looks you can always rent a megapress
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