Stainless Steel Pillar Valves?

[ATTACCA]

Hi all,

have any of you ever seen pillar valves that were entirely made from stainless steel? I'd like to get some for my tanks, but all the well-known scuba gear makers seem to use chrome-plated brass for the valve body. Maybe there is a good reason (other than cost) for using brass instead of steel that I'm not aware of?

Thanks for your help,
Chris

 

[Jimmer]

First off I dont think there are any SS valves, secondly, why do you want stainless?

 

[ATTACCA]

Thanks for your reply. There are three reasons:
1) Stainless steel is much more rugged and corrosion-resistant in general.
2) My first stages are made of stainless, so the combination with brass should favor galvanic corrosion.
3) The looks would match the rest of my gear, because all other metal parts are 316 stainless.

Now those are not huge issues, but if I have the choice, I'd rather take the stainless valves...

 

[deepstops]

Thanks for your reply. There are three reasons:
1) Stainless steel is much more rugged and corrosion-resistant in general.
2) My first stages are made of stainless, so the combination with brass should favor galvanic corrosion.
3) The looks would match the rest of my gear, because all other metal parts are 316 stainless.

Now those are not huge issues, but if I have the choice, I'd rather take the stainless valves...

What kind of first stage do you have?

 

[Jimmer]

Thanks for your reply. There are three reasons:
1) Stainless steel is much more rugged and corrosion-resistant in general.
2) My first stages are made of stainless, so the combination with brass should favor galvanic corrosion.
3) The looks would match the rest of my gear, because all other metal parts are 316 stainless.

Now those are not huge issues, but if I have the choice, I'd rather take the stainless valves...

1) Rugged I suppose, Chrome plated brass is quite corrosion resistant, you wont find a huge difference with stainless, otherwise chrome plated brass would be shunned by divers, especially salt water divers.
2) Galvanic corrosion is only a concern if the regs are left in the valves a very very long time, and even then I would only be slightly worried about DIN fittings, as Yoke fittings have such a tiny amount of contact surface with the valve, that it would be just about impossible to initiate any galvanic corrosion.
3) No argument there I guess, although to my eyes (and I deal with 304 and 316 SS EVERY DAY at work), I dont really see that big a difference between chrome plate and polished SS.

In my mind as an engineer that designs products using SS, I would hazard a guess that the material costs are not the major issue for choosing brass over SS, as brass is also fairly pricey, and chrome plating can be expensive as well, but the fact that brass is maleable and very easy to forge. SS is a PITA to forge and machine compared to brass. Ultimately when it comes to a cost V advantage comparison, I just dont see SS justifying itself for use as a scuba valve.

P.S. If galvanic corrosion between dissimilar metals were that big a concern with chrome plated brass, we'd see A LOT of valves permanently stuck in steel and aluminum tank threads.

Jim

 

[Luis H]

I agree with Jimmer.

From my experience as a regulator technician (started in 1971) and as a mechanical engineer with a few years in the marine field, the 18-8 family of stainless steel (304, 316, etc.) would not be my first choice for scuba valves or regulators. The only exception is some specific parts such as springs and some internal parts like push pins, pistons, etc. Most of this parts are somewhat isolated from other metal parts.

There are other higher corrosion resistance stainless steels (such as 17-4PH), but I can’t think of any advantage to using SS for main bodies, etc.

Chrome plated parts are really durable for scuba regulators and valves. I have some Scuba valves that over 50 years old and they work as good as new. They will probably be fine for another 50 years.

The actual rugged feature of stainless makes it less forgiving in mating parts if they do not have a perfect fit or there is any foreign mater in the mating area. A brass part are far more forgiving even if they have some minor damage.

 

[ATTACCA]

Deepstops, the first stages are Atomic ST1s. I don't have them yet, but I'm planning to purchase two of them and set up independent doubles.

I've found some stainless steel valves in the meantime. They seem to be intended for rebreather use, though. I'd like to post the link, but the board software doesn't allow me to...

 

[Gilldiver]

I agree with Jimmer.

From my experience as a regulator technician (started in 1971) and as a mechanical engineer with a few years in the marine field, the 18-8 family of stainless steel (304, 316, etc.) would not be my first choice for scuba valves or regulators. The only exception is some specific parts such as springs and some internal parts like push pins, pistons, etc. Most of this parts are somewhat isolated from other metal parts.

There are other higher corrosion resistance stainless steels (such as 17-4PH), but I can’t think of any advantage to using SS for main bodies, etc.

Chrome plated parts are really durable for scuba regulators and valves. I have some Scuba valves that over 50 years old and they work as good as new. They will probably be fine for another 50 years.

The actual rugged feature of stainless makes it less forgiving in mating parts if they do not have a perfect fit or there is any foreign mater in the mating area. A brass part are far more forgiving even if they have some minor damage.

I would add that brass is not subject to galling like stainless is.

 

[pescador775]

In industry, stainless high pressure valves are very common. They are made in all shapes and sizes. As has been mentioned, stainless valves are not as easy to fabricate and can be very expensive if purchased new. It may be that some imports are cheaper but one has to find a valve to match the regulator. I do remember seeing some rebreather valves but I don't recall the format. It may well be that there are DIN hookups. Brass valves are tremendously strong. If you have ever seen an old 1/2 NPT post valve removed from a tank using a two foot breaker bar you would agree, I think.

 

[widget]

Yeah, I agree SS Valves are very common in industry but I have never seen a scuba valve of Stainless Steel, I would guess cost is a big factor and maybe lifespan or durability, scuba valves operate in a fairly harsh enviroment and damage is quite common, so it makes sense to make them of a cheaper material which are not going to cost an arm and a leg to replace.

Personally, I think you may end up with matching issues (ie) valve to cylinder thread, to regulator, to left post handwheels, check carefully everything mates up with your present set up before you buy, or they may end up as very expensive doorstops.