STA / BP maintenance

[Homunculus]

i was not sure where to post this question but since STA is a part of a BCD i thought it could be an appropriate place.
i've noticed several very small corrosion spots on my SS STA. BP is in prestine condition. I only dove twice in salty water. Both BP and STA are from Hammerhead. They said on their website "The cold water STA is manufactured from 316 marine grade stainless steel. It weighs 5 lbs 3 ounces and is unfinished. We don't shot blast the STA's to keep your purchase price down." My understanding is that shot blasting does not have anything to do with corrosion. Having said that, i gave it to my friend who works with steel and my STA was blasted (i'm not sure exactly how). in any case, i'm thinking of cleaning rust spots with sandpaper and then applying some ZRC (zinc-rich cold galvanizing compound). I might even paint over it with appropriate paint.
I'll give Hammerhead a call tomorrow to see what they say.
I'm wondering if anyone experienced similar problems with corrosion of BP or STA? if so, what have you done about it? Any comments would be appreciated.

 

[cool_hardware52]

i was not sure where to post this question but since STA is a part of a BCD i thought it could be an appropriate place.
i've noticed several very small corrosion spots on my SS STA. BP is in prestine condition. I only dove twice in salty water. Both BP and STA are from Hammerhead. They said on their website "The cold water STA is manufactured from 316 marine grade stainless steel. It weighs 5 lbs 3 ounces and is unfinished. We don't shot blast the STA's to keep your purchase price down." My understanding is that shot blasting does not have anything to do with corrosion. Having said that, i gave it to my friend who works with steel and my STA was blasted (i'm not sure exactly how). in any case, i'm thinking of cleaning rust spots with sandpaper and then applying some ZRC (zinc-rich cold galvanizing compound). I might even paint over it with appropriate paint.
I'll give Hammerhead a call tomorrow to see what they say.
I'm wondering if anyone experienced similar problems with corrosion of BP or STA? if so, what have you done about it? Any comments would be appreciated.

Mikail,

You might want to research "Passivation" Free Iron in the surface of SS (even 316) can act as a starting point for corrosion. Stainless Steel can pick up ferric particles during manufacturing of the SS sheet, or when parts are fabricated from the sheet using steel cutting or forming tools.

Sand or bead blasting can provide a level of mechanical passivation by "scrubbing" the surface of the formed Stainless part.

Other methods of passivation include heated nitric acid baths and electropolishing.

It has been my experience that well passivated 304 Stainless will remain reliably rust free longer than unpassivated 316.

A simple DIY method for treating your rust stained SS part is to soak in Coca Cola...

Good luck,

Tobin

 

[David P]

A simple DIY method for treating your rust stained SS part is to soak in Coca Cola...

Tobin

Now thats a new one! I gotta find some rusty SS tomorrow to play with experiment with.

 

[Homunculus]

makes sense though. i recently checked coca-cola's pH in the lab. it was 3.5!!!

 

[chewie]

you can also wash the grime from your wheel rims by rubbing coke with aluminum foil. there was one of those forwrded emails about the different usage of coke

 

[String]

Vinegar works better.

You tend to see some dissimilar metal corrosion around the screws and washers. If you have an Aluminium backplate and use stainless steel screws then you'll get some. Not a major issue though but cant really be avoided.

 

[The Kraken]

When stainless parts are shot blasted, there may occur a small amount of particle impingement from other carbon steel particles picked up in the blasting media.

Quite often one can find small areas of rust on stainless steel parts which have come into contact with tools or media that have been used, previously, on carbon steel products.

the K

 

[cool_hardware52]

When stainless parts are shot blasted, there may occur a small amount of particle impingement from other carbon steel particles picked up in the blasting media.

Quite often one can find small areas of rust on stainless steel parts which have come into contact with tools or media that have been used, previously, on carbon steel products.

the K

True,

That's why we keep seperated the abrasives (belt sanders, scotch brite, vibratory media etc.) that we use on SS parts.

Tobin

 

[The Kraken]

I like good quality control !!!!

the K

 

[snepdiver]

Just another reason to add to my list of reasons to buy DSS when I get ready.