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steam headers and swing joints

Sam G.
Sam G. Member Posts: 12
A recent thread got me thinking about headers and swing joints.

After 30 years in the business, I have seen a lot of steam headers. Copper and steel. Welded, soldered, and threaded. With and without swing joints. With and without flanges. Take-offs in every possible position. I have seen boilers fail due to low water, age, bad design and manufacture, mineral clogging, rotting, and general misuse. I have never seen a boiler fail due to uneven expansion of the header and boiler sections.

That being said, long ago I saw the holy light, as spoken by the high prophet and priest Dan H. “The wanderer from Long Island”. I only install steel headers with swing joints.

My question is this: Is it the actual threaded fittings that flex and move to absorb the expansion, or the vertical riser that torques and twists to do the same? (My question arises from our use of EXPANDO thread sealant that creates an almost welded pipe structure. It is a great product. Never a threaded joint leak, but almost impossible to unassembled once set.)

Just the ramblings of a wethead on a hot summer day.


  • Al Letellier_9
    Al Letellier_9 Member Posts: 929
    swing joints

    "for every action there is an like and equal reaction" Unlike you, I have seen at least a half dozen cracked steamers from the lack of swing joints. I am not an engineer but all the joints work together to adsorb the expansion and contraction of the header and boiler. I tend to stay away from Expando for steam headers. It is great stuff in the right application, but we always use teflon tape and pipe dope together. Recently took apart a header I installed over 15 years ago to add a section to the boiler and no sweat, apart it came.....with a the same size pipe wrench that it went in with. (thank God for elastomer seals).
  • Boilerpro_5
    Boilerpro_5 Member Posts: 407
    I have seen it too...

    About a 4 year old WEil Mclain LGB, oversized and short cycling too with a welded header....leaks at all the top connections. Around here Weil's usually last about 15 to 17 years before leaking...Typically at the bottom joints, rotted out castings, or due to flexural stress at the point where the end castings's the water jacket narrows down to the support legs. I mostly see EG, EGH models around here though.


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