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Stripped a flange bolt on a 10-inch pipe and it cost me half a shift
I was working a job at a paper mill in Tacoma last Tuesday, tightening up a flange on a 10-inch steam line. One bolt felt tight, so I gave it a little more torque with my impact gun, and it stripped clean. Had to drill out the bolt, retap the hole, and find a replacement from the supply room. Took me almost 4 hours total, and the foreman was breathing down my neck the whole time. Has anyone else had luck with using thread chasers on older flanges to avoid this crap?
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haydenbutler18d agoMost Upvoted
Man, I feel your pain on that one. In my experience, thread chasers can be a lifesaver on older flanges, especially if you run them through by hand first to clean out any crud or old thread lock. I always keep a set of both inch and metric chasers in my bag, and I'll hit the bolt hole with a wire brush and some penetrating oil before I even think about torque. Your mileage may vary, but I find that using a torque wrench set to the lower end of the spec helps too, since impact guns can easily overshoot on rusty bolts. Take this with a grain of salt, but sometimes just swapping out for a slightly longer bolt in the same thread pitch can give you fresh threads to bite into without having to retap.
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On a 10-inch steam line, most flanges use 1-inch or 7/8-inch bolts, so a slightly longer bolt in the same thread pitch would just bottom out in the blind hole without giving you new threads to grab. In my experience, swapping bolt length works better on through-hole flanges where you can add a nut on the backside, not on tapped holes like that. Your mileage may vary, but I'd stick with thread chasers and a good tap set for those blind flange holes.
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