Stainless steel fused to aluminum

[Tyrrell]

While tying to replace an aluminium life line stanchion I was unable to remove the stainless steel bolts holding it as the bolts had fused to the aluminium stanchion. Any suggestions re how to free the bolts?

[TerryLL]

Depending on the alloys, you may be out of luck. Always a good idea to use anti-seize thread goop when using SS. Even SS nuts on SS bolts will often gall and seize up to the point where cutting or twisting them off is the only option.

You might first try smacking the bolt head with a hammer to break the corrosion, and even hitting the head as you are turning it with a wrench. After that I'd lay some serious heat on the bolt with a propane torch, if you can do it without damage to the boat. Last resort is to cut or twist it off, and redrill for a new fastener.

[bruce w]

put a short bar in the hammer drill and give it a rattle on the top ,or use a air spanner , hammer and blunt punch around the head, warm and quench , then get rough with it ,wring it of and drill .

[Bill Mercer]

Depending on the size of the screw, you may be able to heat it up enough with an electric soldering iron to do some good--I've used that as a quickie stuck screw remover on cars, but never on bolts or anything large. You're a lot less likely to burn your woodwork with an electric soldering iron than a mapp torch.

[George Ray]

In shipyard we used heat.
Alum gives almost no colors cues before it melts so we soot it up with yellow flame and when it is BLACK with soot we go to a neutral flame and start to heat evenly and carefully. The soot burns off at a safe (non-melt) temp and at that point frozen stainless can usually be turned. The turn/removal needs to be done quickly as the alum shrinks quickly as it cools and the stainless tightens up again.

[George Ray]

?? How did the job go ??

[Ian McColgin]

Tear the whole thing out and start over with proper base and proper ss stanchions. Your safer with no lifelines than with a unit made to fail.

[George Ray]

Good point, ...... way too easy for me to get lost in the details.

[paladin]

and yure gonna go to a lotta trouble to try to undo something that folks pay a fortune to have done....explosively bonding the two metals together.....