304 stainless vs galvanized steel in marine environment


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Old 03-03-23, 09:43 AM
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304 stainless vs galvanized steel in marine environment

I need to fabricate a guide plate for a gangway ramp. Local suppliers only carry 304 stainless in the flat bar dimensions I need. 316 would be ideal. Is it better to go with the 304 or use mild steel and HDG it: which would add better protection? The piece in question would be in salt water but close to it.

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Old 03-03-23, 09:56 AM
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Don't be afraid to put together a list of what you need (316 St St) and see if your local suppliers can throw it in with one of their regular material orders.

My gut would be to go with the 304. Hot dip galvanizing can be pretty expensive for small "speical project" batch sizes. Plus, stainless is stainless all the way through. A scratch through the galvanizing will allow steel to rust but a scratch on stainless will at the most develop light cosmetic rust.

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I've made things for the dock at the coast. It's on the ICW on the back side of a barrier island of NC and gets salt spray that blows over the island plus splashes of salt water. The 304 does eventually show some rusting. It produces light surface rust along the grain of the surface texture I created along with some pinprick spots of rust. Many of the parts I made I didn't use dedicated stainless steel tools, sanding belts or buffing wheels so I'm certain at least some of the rust is cross contamination with carbon steel that got impregnated in the stainless during fabrication. But, after years there's only light surface rust. 316 parts do fare better but still suffer from cross contamination cosmetic rust if your not careful.
 
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Old 03-03-23, 10:10 AM
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Stainless is forever!
 
 

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