316 ss grade or what? 6

[stickerpen]

Hello,

I am a starting engineer. During material selection I see 316ss as a grade sometimes, like A182 gr 316?
and sometimes 316 is given by itself like in valve trims specification?
I have read many ASTM docs and many others but one thing I cant understand is what is the meaning of A182 vs 316?
Am I guessing correctly? 316 SS - determines the content of steel(ingredients or chemical composition?) and A182 means way of manufacturing the part(eg.ball of a ball valve) and in this case it is forging that means it is forged 316?

Any answer is highly appreciated!

 

[stickerpen]

For example, in NACE MR0175 in one of the tables 316 is given seperately under AISI when A351 is under ASTM? A182 is also under astm but it can be gr 316??

 

[XL83NL]

There's (typically) always a product form and grade. The former will tell you how the product is made (pipe, forging, bar), the latter it's grade (AISI 316, 304L, etc.).

ASTM material specs, like A182, A240, A312, are specifications for the manufacture of several product forms (forgings, plate and pipe, respectively).
Each ASTM material spec includes several grades, so ASTM A182 may cover more than 30 grades. The spec only details how the grades are fabricated and tested during manufacture.

Within ASTM A182 (forgings), you can have material grade 316. This would become ASTM A182 F316. Note the 'F'.
For pipe, the material spec would be e.g. ASTM A312. If the grade is 316, this would be designated TP316 within ASTM A312 (thus ASTM A312 TP316).
ASTM A351 is for casting (e.g. valves). 316 grades within ASTM A351 are designated (I believe) ASTM A351 CF8M.

Same approach counts for EN-standards, but they work with werkstoffnumbers (e.g. EN 10222-5 1.4404 would be a 316 forging, for e.g. a flange)

 

[EdStainless]

The correct way (to reduce errors) to refer to alloys is using the UNS #, these are composition specific regardless of the the product form.
So the alloy that we generically call 316L is S31603. And yes, there is a big book full of them.
The AISI does not assign designations any longer.
ASTM only includes common names if they have been in use for many years.
The EU has promised to start using UNS in place of the three current systems, but they seem to have neglected to say when they would do this.

Joining ASTM is easy, you don't have to attend meetings. Just sign up and pay, and you get a free volume of specifications that sells for more than your membership fee. Join a committee of interest to you (steel, tubulars, non-ferrous, etc).
Then vote by email when the ballots come out.
This will keep you informed of what changes are coming.
This is a good idea because when you write a spec number down that is the basis of the contract. You had better posses a current copy of that spec so that you know what is required. It doesn't matter if you are the buyer or seller, it is still a binding obligation.

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Plymouth Tube

 

[tbuelna]

In the aerospace world, "316" is generic term for austenitic corrosion resistant steel alloys having a certain composition. And there are numerous AMS specifications covering the different raw material forms (bar, sheet, tubing, casting, forging, etc) and quality levels 316 might be supplied in. The formal way to specify the material and form is by using the appropriate AMS specification, followed by any form, class or grade defined in the spec.

It is always good practice to provide a specific description of what your design requires, and never leave anything open to interpretation.

 

[mrfailure]

To further clarify: The grade (for example 316 or 316L) refers to the specific steel. There is a book that lists UNS (and corresponding old AISI) grades of material. Note that these grades are only valid for chemistry, and not for other properties If you have been given an ASTM standard such as A182, you should make sure to use the composition listed in that standard and not the one in the UNS book: sometimes there are deviations and additional elements in compositional limits in the ASTM standard compared to the generic limit. ASTM standards will also include other property requirements for your individual product form (for example, hardness, quality, and strength). Finally, note that if you are looking at parts that have been in service, you should use the version of the ASTM spec that was effective at the time of manufacture.