Marcin2005:
I'm contemplating switching from a traditional BC to a backplate and I'm not sure what I should look for? I've seen some on ebay but most are made out of 304 steel. Is this sufficient of should I pay more and get something made out 316L.
BTW Im trying to avoid prices charged by OMS and other big name manufacturers.
Thnx for your help.
304 AND 316 are both corrosion resistent. 316 has advantages in extremely corrosive environs, like chemical plants, or at elevated temps, i.e. hot nasty fluids.
In my opinion passivation is more important. Whenever SS is in contact with steel tooling, like at the rolling mill, or when is cut, drilled, bent etc. there will be transfer of "free iron" to the surface. This free iron, if not treated, will provide a place for corrosion to start. This is true for 302, 303, 304, 316 etc.
Passivation removes this free iron. Most passivation is done by hot nitric acid (don't try this at home)
Correctly passivated 304 will often outperform unpassivated 316 in marine environment.
Keep in mind that aluminum (tanks) and brass (regs and fittings) are routinely used in scuba, and with fairly minimal care (rinsing post dive) perform quite well.
In short 304 should be fine.
Regards,
Tobin