Stainless steel nuts on Galvanised mild steel.

[30boat]

Going back to the original question,would Duralac work in this application?

 

[conortoo]

My boat has a lead keel with stainless steel bolts. The presumably mild steel nuts had been exposed to bilge water and had corroded.I replaced them with stainless steel nuts 316. Since doing this I am wondering if I have done the correct thing. Would I be better with mild steel nuts to prevent degradation to the keel bolts.

 

[30boat]

My boat has a lead keel with stainless steel bolts. The presumably mild steel nuts had been exposed to bilge water and had corroded.I replaced them with stainless steel nuts 316. Since doing this I am wondering if I have done the correct thing. Would I be better with mild steel nuts to prevent degradation to the keel bolts.

Don't worry,you're ok.My old boat had a lead keel (oh how I miss it) with stainless bolts and nuts.Not a problem for 20 years.And since it had a keel stepped mast they were always wet.

 

[macd]

Don't worry,you're ok.

Indeed he is. He's still posting almost two years after he asked the question

 

[Poignard]

A method that used to be used on tankers to prevent nuts from corroding onto bolts was to put brass nuts on carbon steel bolts. Effective and far cheaper.

That's a good tip. I always use brass nuts on the m/s studs of exhaust manifolds. They're always easy to remove. Avoids broken studs etc.

 

[conortoo]

My boat has a lead keel with stainless steel bolts. The presumably mild steel nuts had been exposed to bilge water and had corroded.I replaced them with stainless steel nuts 316. Since doing this I am wondering if I have done the correct thing. Would I be better with mild steel nuts to prevent degradation to the keel bolts.

Im no scientist but on reflection im going to put some mild steel nuts on top of the stainless ones as there is a bit of the bolt protruding.

This will leave the mettallurgic!? setup the same as fitted by the manufacturers with the benefit of rustfree stainless bolts carrying the load.

I dont know if this will have any positive effect other than on my peace of mind.

 

[vyv_cox]

Im no scientist but on reflection im going to put some mild steel nuts on top of the stainless ones as there is a bit of the bolt protruding.

This will leave the mettallurgic!? setup the same as fitted by the manufacturers with the benefit of rustfree stainless bolts carrying the load.

I dont know if this will have any positive effect other than on my peace of mind.

I suspect that manufacturers use mild steel nuts on stainless steel keel bolts to prevent any possibility of galling. In a dry bilge there should be no problem and even if the nuts rusted badly they would be easier to remove than galled ones, which might as well be welded to the studs. However, I can see no benefits in putting mild steel nuts on top of stainless steel ones.

 

[MM5AHO]

I thought from all the recent news sources that nuts were plenteous in Greece, and that few of the residents seem galvanized to pay taxes?
Or did I misunderstand the news?

 

[Len Ingalls]

Can you thread SS or plain steel nuts on hot galvanized bolts/studs,etc?
I've always found plain nuts go very reluctantly over hd galv. & galv. nuts wobble on plain steel,but I'm on the left side of the pond.

 

[MM5AHO]

Can you thread SS or plain steel nuts on hot galvanized bolts/studs,etc?
I've always found plain nuts go very reluctantly over hd galv. & galv. nuts wobble on plain steel,but I'm on the left side of the pond.

Mostly, when both bolt/stud and nut are galvanized, the thread on the nut is overcut after galvanizing to get a good fit. If this oversized thread is then put on a plain steel stud, then it will be a little loose.
The thickness of the galv on the threads will be about 30-40 microns, but on each face. So multiply by number of meeting faces and the interference can become significant.