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Question about swing joints

mattyork Member Posts: 5
edited February 2021 in Strictly Steam
My education has included drop headers, over sizing headers, appropriate length of risers etc. My question is this: I have seen many risers (1 or 2) and come up and turn 1 90 and cross the boiler over to the equalizer, with the steam main takeoff as expected. My question is for those installations that don't utilize drop headers. Often the risers turn 1 (one) 90 and there isn't an additional 90 to 'lay it down' or turn horizontally. In other words, the risers and header (going over to the equlizer) are on the same vertical plane. Is that acceptable for the professional? If it's screwed black iron, have we accomplished a swing joint, or is the nature of an effective swing joint is that always has to lay down horizontally? (drop header or not)


  • The piping diagrams supplied by the manufacturers usually specify the straight up and over approach piping as a minimum standard. It does insulate the boiler block from some of the difference of lateral expansion between that and the header piping.
    The drop header will provide even more expansion/contraction protection, with the added important bonus of separating out any water which blows up the risers, and directing it into the equalizer, and the wet return. I believe that a welded header can only be used with such a drop header.—NBC
    EBEBRATT-Ed Member Posts: 15,512
    A swing joint is considered to be 2 elbows, a double swing is considered to be 3 elbows.

    I used to get into this with underground oil tanks. They always insisted on double swing joints set up so the joints would tighten if the tank settled.

    Look up the expansion of steel pipe from a temp rise of 200 degrees. It is very little on a short run. In fact it's 1.55 "/100 feet of pipe. So a 3' riser or header the expansion would be only .0465"
    10' of steel pipe=.155" just over 1/8"

    What you don't want to do is put stress on the boiler sections. Just visualize the piping connected to the boiler. If the risers can move so the boiler won't be stressed your good
  • Jamie Hall
    Jamie Hall Member Posts: 23,272
    A swing joint -- see @EBEBRATT-Ed 's comment above -- will take up angular misalignment --viewing from the side, the pipes aren't at right angles. It's often required in steam piping, as the "horizontal" pipes aren't actually horizontal -- they have to pitch -- but the vertical pipes are usually set vertical (leaning pipes bother people), and you need a swing joint to do that.

    A double swing joint will take up angular misalignment, but it will also allow each pipe to move longitudinally with expansion (or other movements -- like @EBEBRATT-Ed 's oil tanks). There are other ways to do that, though, depending on which pipe or pipes you expect to expand and where they are restrained.
    Br. Jamie, osb
    Building superintendent/caretaker, 7200 sq. ft. historic house museum with dependencies in New England
  • EdTheHeaterMan
    EdTheHeaterMan Member Posts: 7,818
    edited February 2021
    I this a discussion on dancing establishments? Swing Joints are OK but I prefer Latin music, Rumba, Samba, Merengue. Just saying!
    Edward F Young. Retired HVAC ContractorSpecialized in Residential Oil Burner and Hydronics