Valve Trim Material

ASTM A105 is a carbon steel. Stellite is Co- Cr Alloy (Chromium will be typically 20% or more).

The stellite will be typically overlaide over the base (A105).

This is not the same as your specification (SS)

The applications will decide what is required. Stellite is usually better - but not alll (stellite is a family) and not under all circumstances. In certain condition (eg Amines in water etc - which attacks the stellite) these are not used.

PS: isn't the stellite only used on the disc and the seat?

The above said material is used only in the body seat ring. The Disc material is ASTM A216 Gr. WCB + 13% Cr. Steel instead of 11-13% Cr. Steel.

The same issue is also with Hinge material where the actual material is ASTM A216 Gr. WCB instead of 11-13% Cr. steel. please comment....

The Disc material is ASTM A216 Gr. WCB + 13% Cr. Steel ?

Is it base metal of ASTM A216 ovrlaid with the Cr steel ?

The total difference is going to be in corrosion resistance of the base metal.

The bottom word is when you are ready to pay for SS (as per your spec) then why do you want to settle for less?

Hat it been stellite over SS I would have straight said go for it.

Careful now.

API 600 specifies:

6.2 Trim
6.2.1 The trim is comprised of the following:
a) stem;
b) body seating surface;
c) gate seating surface;
d) bushing, or a deposited weld, for the backseat and stem hole guide;
e) small internal parts that normally contact the service fluid, excluding the pin that is used to make a stem-to-gate connection (this pin shall be made of an austenitic stainless steel material).

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In any respect, you do have some valid questions/points that need clarification. Maybe your purchase order was vague, or maybe the supplier provided something totally wrong.

Hakr5, I am confused with your situation. Can you provide a detailed breakdown of what EXACTLY the purchase order said, and what & where you are getting the actual supplied material specifications.

And also the application and the fluid, pressure, temperature, code requirements or absence thereof?

Dear friend

Please see the attached details in actual material specification and supplied material...

Alright!!!! Now we are getting somewhere. It appears that you are indeed specifying/requiring an API (600, 602, or 603) valve. And that service seems benign, diesel fuel, nitrogen, ....

However, I can't really read that spec sheet.

Can you upload a better quality sheet to another free service site.

Dear Guest

Please go through the below link....

http://www.4shared.com/file/252826058/e538657d/Material_Spec.html

Right on!!!

Besides my initial mistake in assuming an API 600 gate valve (I should have realized this error after your intial posted pictures) that you are in fact dealing with a (swing) Check.

NOW, this may be irrelevant or VERY important. It seems you have given two different specs. The first picture was a multitude of benign service, BUT the 4shared one is a "NACE" hydrocarbon service. WHICH ONE IS IT, or this a hypothetical question that may pertain to a lot of valves.

I have to confirm, when I have time, exactly what the BS 1868 & BS 5352 specs say, which you should realize is what is required in your spec for check valves

Can you clarify why, if on purpose, or by accident, or irrelevant (in your eyes) why you have posted two different Piping Specs.

ALSO of very significant importance, but which still requires conscious thought/approval - it seems the "Trim" spec calls for a minimum of 11-13% CR.

Dear Guest

This valve is meant for (NACE) hydrocarbon service. The earlier picture was posted accidently...

You don't specify WHICH NACE standard it must meet. I PRESUME you mean MR-0175, but you do not make that clear (there are more than one). MR-0175 is specifically concerning Sulfide Stress Corrosion Cracking in Sour (H2S) service. You do not specify which level of compatibility is required. Stellite overlay of Carbon Steel is USUALLY acceptable per level 4 and API 6A PSL-3/4. But your customer may have other requirements. whenever in doubt, ask the customer for an opinion and GET IT IN WRITING. That way if they say it's fine, and later on find out it isn't, they can't sue you later.

I would suggest that unless the external environment dictates it, that the overlaid stellite will in MOST circumstances greatly exceed the requirements given. in addition to the corrosion resisitance of the cobalt/chrome base material, you'll have the erosion resistance of the Carbides. Stellite overlay of carbon steel is often the "standard" material offered as an overlay of a cobalt based alloy over carbon steel gives you the best of both worlds: inexpensive and strong base material covered with a thin layer of a very expensive, but corrosion/erosion resistant material. generally speaking such corrosion resistant materials aren't terribly strong or cheap.

I would consult with a metallurgist for your specific situation, but my gut feeling is that you are being supplied a vastly superior product.