Is it better to align drums by feel or by the numbers?

I've been in the shop long enough to see both sides of this fight. Some of the old guys I work with swear you can just eyeball the drum alignment and know if it's square by how the chain rides. But then last month we had a 50,000 gallon tank where one guy did it by feel and the seal was off by a quarter inch after the first hydro test. I'm the type who trusts my levels and dial indicators more than my gut, but maybe it's just me being too cautious. My buddy over at the Sioux City plant says they only use laser alignment now and never have issues. But I've also seen a crew spend 3 hours chasing a perfect number when the old hand could have shimmed it in 20 minutes by feel. So which method actually holds up better in the long run when you're doing pressure vessel work? Anyone got a horror story from trusting the wrong approach?

2 comments

2 Comments

robin8361mo ago

What about the temperature of the metal when you're setting that alignment

paul_webb451mo ago

That part about "chasing a perfect number" really stuck with me because I watched a guy do that once on a 30 inch manway for a scrubber. He had the laser out, tweaking it for almost an hour, meanwhile the client was standing there watching his watch. But then when we pressured it up, that thing held better than any drum I'd ever seen done by eye, so go figure. I think there's this middle ground nobody talks about where you use the numbers to get you in the ballpark and then trust your feel for the final shim. My old foreman used to say that numbers tell you where to start and your hands tell you where to stop, which made a lot more sense to me after a few years of doing this.