The difference in backplates

[Akimbo]

I learned from the owner of Deep Sea Supply that there are different grades of stainless. Some are more rust and stain resistant than others -- obviously, the better ones are more expensive.

There are three primary grades used on backplates; 302, 304, and 316 “Marine grade stainless”.

You can often get similar salt water corrosion resistance from general purpose 302 and 304 grade stainless that has been Passivated as 316 for relatively low exposure applications like a backplate — unless you keep in on deck exposed to salt spray continuously.

The rust you get on a backplate, or diving gear in general, tends to be a light staining rather than pitting or running rust. Stainless used in knives is usually a 400 series because 300 series has too much Nickel, which makes the stainless too soft to hold a decent edge.

Even 316-L can suffer corrosion pitting. All you need is for some moron to spray it with sparks from grinding steel nearby. A good fabrication shop will segregate grinding and polishing tools used on stainless and steel to prevent this problem. Unless really severe, passivating will correct this problem.

All stainless corrodes. It is the corrosion or oxidation that creates a thin chromium oxide layer that protects it. The chromium oxide film prevents further surface corrosion by blocking oxygen diffusion to the material below. That film is “self-healing”, meaning that scratches in the chromium oxide film will be repaired by generating more film in that area — unless the scratch is imbedded with a material like iron particles that will interfere with the chemistry.

You can’t tell the difference between any of the 300-series grades of stainless by looking. You need to trust the supplier or require mill certifications. All 300 series are non-magnetic. IMHO, fabrication quality is much more important than the grade in this case.

 

[Lorenzoid]

Akimbo, would rinsing a BP with fresh water after a dive essentially eliminate pitting, or does the pitting occur during the relatively brief exposure to saltwater during a dive day? In other words, is it only when someone foresees not rinsing his gear that he might want to be concerned about what grade of stainless his BP is made of?

It's hard to believe that corrosion resistance should merit even minor consideration in choosing a SS BP.

 

[Tony387]

Do I have to have a sta with the palantic or do u have to have a sta with all bpw setups?

With my DR wing, no STA was necessary. It was a perfect fit. It has three pairs of slots, and I can use all three. I'm not sure what grade SS it is, but I have zero stains or corrosion on mine, and I dive it every weekend.

Sent from my SCH-I545 using Tapatalk

 

[Akimbo]

Akimbo, would rinsing a BP with fresh water after a dive essentially eliminate pitting, or does the pitting occur during the relatively brief exposure to saltwater during a dive day?...

Pitting will be caused by poor fabrication procedures and is pretty rare on delivered plates. You can cause pitting by “tuning up” a plate. For example using Emory Cloth contaminated with steel filings to round the slots on your plate or buffing it with steel wool. Same with a Drumel tool bit that has been used on steel.

…It's hard to believe that corrosion resistance should merit even minor consideration in choosing a SS BP.

Unless you are anal about the slightest bit of ultra-thin surface corrosion that can be buffed out with an abrasive pad, you really don’t need to worry about getting 316 stainless. It can make a real difference in severe marine environments, but not on a backplate.

Note the tiny rust stain in the attached image. This is from not rinsing an older 304 Freedom Plate for more than a week of diving. The new Freedom Contour Plates are now 316 stainless just to eliminate this level of rust.

 

[Rich Keller]

If you are looking for something different, more comfortable, cheaper, with a lower profile and no need for a STA you could try a commercial diving harness. You would have to make your own holes for the wing as these were not made to be used with a wing but they work very well and I have seen them on ebay as cheap as $25.

 

[bsppc]

Oxycheq wings and DR plates do not work together. Cam band slots are off by over 2" on new production from both suppliers.

 

[ams511]

Oxycheq wings and DR plates do not work together. Cam band slots are off by over 2" on new production from both suppliers.

If you are looking for an inexpensive plate, I would check with Edd at Cave Adventurers. I believe his plate is compatible with Oxycheq.

 

[buddhasummer]

Oxycheq wings and DR plates do not work together. Cam band slots are off by over 2" on new production from both suppliers.

I'm curious who changed what as I used to have both and they worked fine.

 

[bsppc]

I ended up trading my DR plate for an Oxycheq plate for a perfect fit. I like the fit and finish of the Oxycheq plate much better and got a great deal as my LDS was closing out all Oxycheq products and gave me a great discount.

 

[cool_hardware52]

Sorta. Some are not very good for doubles because they have too shallow of a bend (DSS). Others are going to eat webbing faster unless you file and/or stone down the edges of the holes cut into the plate because the place you save money is on the finish. The cheapest will be lighter and more prone to bending, because they're a thinner gauge and/or cheaper steel or cheaper alloy.

At the end of the day, there's only so much difference between plates of metal with more or less the same hole pattern, but there are quality differences. Whether the differences are worth the additional coin is between the buyer and themselves.

DSS plates are used with doubles all the time. As long as the tank band bolts haven't been too short there is no problem.

Tobin