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McDonnell Miller 193-7b

SlamDunkSlamDunk Member Posts: 832
We stripped a bolt hole in an 8 hole flange on the body of our LWCO. We have a replacement and will replace the body but out of curiosity, and in the hopes of saving labor, we asked our inspector if a heli-coil would be acceptable to repair the bolt hole and he said no, unless the manufacturer provides a letter that says it is an approved repair. That seemed more labor intensive than replacing so we are replacing. I understand the liability but what do you think? Would a helicoil be an effective repair? I've used them on jet engines legally. The boiler is a 600HP. 150 psi max.


  • retiredguyretiredguy Member Posts: 227
    edited December 2019
    If the stripped bolt hole was one that could utilize a "bolt and nut", I would drill out the stripped thread and use a bolt and nut. If the stripped bolt hole is one with the blind threads, you could drill it out to the next size bolt and "tap " the new drilled hole and make sure that you use a bottoming tap to get the most threads you can. Going forward, get yourself a can of "anti seize" found at many locations including auto parts stores. Use it on the gasket and all the bolts. I used it on anything where the connections would seize due to heat such as a high pressure steam boiler. I always had a can in my service vehicle. I never used a Heli-coil on a high pressure steam boiler however some service techs did use them. I was always too safety conscious.
  • SlamDunkSlamDunk Member Posts: 832
    Those are great suggestions. Unfortunately, This is the one bolt hole that is too close to the body to use a nut or up size. In fact, the mfrs tapped hole cut into the body slightly, it is so close. Thanks though. Will keep those ideas in my back pocket. We always use anti seize and we also use new bolts whenever we open up. After 12 years, and different people, it was bound to happen sooner or later.
  • EBEBRATT-EdEBEBRATT-Ed Member Posts: 7,081
    I agree with not taking any chances with high pressure steam
  • SlamDunkSlamDunk Member Posts: 832
    Have to respect the inspector. New one is in. it really wasn't that labor intense.
  • SeanBeansSeanBeans Member Posts: 483
    Man, those helicoils are pretty cool!
  • SlamDunkSlamDunk Member Posts: 832
    I can't tell you how many engines and manufacturing equipment I have used them in. I was surprised when the inspector said no.
    Probably because they are not idiot proof and accident investigators look for the idiot.
  • Hap_HazzardHap_Hazzard Member Posts: 2,263
    Helicoils are stainless. You usually get a little galvanic activity in cast iron in wet locations. Maybe that's why they nixed it. ¯\_(ツ)_/¯

    When you can't heli-coli it, heli-arc it. :D
    Just another DIYer | King of Prussia, PA

    1983(?) Peerless G-561-W-S | 3" drop header, CG400-1090, VXT-24
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