Debate: Should we use penetrants on seized bolts or just heat them? Ran into a nightmare underwater.

I had a job in Portland last month where a valve bolt on a pipeline was completely seized at 30 feet. I tried Kroil first, waited 20 minutes, nothing. Then I switched to a torch-underwater welding rod trick, took another 45 minutes to free it. My partner swore the penetrant would've worked if I'd let it soak longer, but I think heat is faster in cold water. What's your go-to when time is tight and the bolt won't budge?

2 comments

2 Comments

bailey.sandra16d agoMost Upvoted

...so you're REALLY gonna sit there and tell me heat is better than penetrant in cold water? I've been diving for twelve years and I've NEVER had a penetrant fail me if you give it the right time. Kroil needs at least an hour in cold conditions, not twenty minutes, that's just impatience talking. Heat might work faster but you risk warping the bolt or damaging the surrounding metal if you're not careful, and at thirty feet that's a recipe for a bigger nightmare. I'd rather take my time with a good soak and avoid having to explain to the client why their valve needs replacing.

nora73515d ago

You said "if you give it the right time" and that's the part nobody's really talking about. In cold water, that hour soak isn't just about the penetrant working, it's about the metal contracting and the threads relaxing. But here's the thing I haven't seen mentioned yet: the type of corrosion matters. If you're dealing with galvanic corrosion between stainless and aluminum, penetrant alone won't cut it no matter how long you wait. Heat changes the expansion rate of both metals differently, which can break that bond without warping anything if you're precise. I've had way better luck with a controlled heat source and a light tapping on the bolt head to shake things loose. Your method works fine for rusty steel, but in mixed metals underwater, heat has saved my bacon more than once.