TIL a trick for stubborn flange bolts on a 30-year-old boiler in Akron

Last week I was on a call for a retrofit in an old apartment building. The flange bolts on the feedwater line were completely seized, like they were welded on. I tried heat, I tried penetrating oil, nothing. Then the super, an old guy who'd been there forever, told me to hit the bolt head dead center with a hammer a few times before trying the wrench again. I mean, it felt wrong, but after three solid whacks with a 3-pound sledge, the first one broke loose like it was greased. Has anyone else got a go-to method for that kind of corrosion?

4 comments

4 Comments

robertlane2mo ago

Actually, you want to hit the nut, not the bolt head.

janah832mo agoTop Commenter

Yeah, hitting the nut is the way to go. I had a rusty bolt on my truck's license plate bracket last month. I kept hitting the bolt head and it just mushroomed over. Once I switched to hitting the nut side with my impact wrench, it broke free after a few good pulses. That saved me from having to drill it out.

the_elliot1mo ago

I've always had better luck hitting the bolt head to break the rust seal. The nut can strip its threads or just spin on you if it's really seized. A good soak in penetrating oil first usually gets it done from either side.

violah432mo ago

Oh man, I feel that pain. Did the exact same thing on my old lawnmower deck, just wrecked the bolt head. Robertlane is totally right about going for the nut. It seems backwards until you see it work. That little bit of give on the nut side makes all the difference, doesn't it?