Anti Corrosion for Steel Accessories

[fishmagnet]

Can anyone recommend anything for corrosion protection for the stainless fittings on Poly Boats?

[Mark]

Stainless Steel alloys are grouped according to the structure of their crystals. Adding nickel creates the structure used in marine applications, called austenitic. Austenitic stainless steels are identified by their '300' series designation.

Grade '304' is a general purpose stainless and is the most common grade of stainless produced. It is made up of at least 18% chormium and 8% nickle offering good corrosion resistance. 304 stainless steel is best suited for indoor use and is inadequate for many marine applications.

Grade '316' offers the best corrosion resistance among standard stainless steel and is often refered to as "marine grade". 316 stainless is made up of at least 16% chormium and 10% nickle. 2% molydenum is also added to 316 stainless to increase its corrosion reistance. Grade 316 is most suited to outdoor and marine applications.

All this means, if your stainless is rusting it might be 304 stainless. The cleaner below will work to help prevent surface rust but you may find that most items rust between the stainless and the plastic. as below

http://i806.photobucket.com/albums/yy350/Markrel/rust.jpg
Although the tube is 316, the bolt that connects under is most probably 304.

Protector will not prevent this, you need to remove the item, clean plastic & stainless & then refit & seal the two joins with Rule elastomer polymer. I was told very clearly NOT to use Sikaflex. (Silicons)

but http://allthingsstainless.com.au/home/stainless-polish-cleaner/nanocoat-metal-2-in-1-cleaner-and-protector.html is the product that may suit your needs. Also for rust stain removal on plastic, the Bar Keepers Friend seems to be the most popular but first try a High Pressure Water Gun.

Hope this all helps
Mark

[bushbeachboy]

Mark, thanks for that explanation of the different types of stainless.2thumbsup Anytime I have asked people about it before the usual answer is 'I dunno'. Is there a reference source for this type of info?

[Dave]

Great info Mark thanks

I have noticed that most SS fitting rust on boats up here. To do with the constant humidity, salty air and cheap SS. Its that bad even wood rustslaugh1 Was at a mates place yesterday and his $50k fibreglass boat had the same problem.

I bought some SS cleats for my boat and they are rusting on the surface rather than the usual area around the screw holes. I should have bought the plastic ones doh