Valve components according to ASTM A182

[phazzevi]

In ASTM A182 is provided that materials shall be forgings as per A788 but at paragraph 6.4.2 it is provided that i can machine cilindrically shaped parts from rolled solution annealed austenitic stainless steel bar without additional hot working.
It seems that if i have an austenitic hot rolled bar certifed for example as per A479 grade 316 and i machine from it a cilindrically shaped part i can certify the component as an ASTM A182 grade F316. Is this a possible/correct interpretation?

 

[gerhardl]

With the reservation that I do not know a thing about ASTM A182:

In any official material specification, materials cannot change name and origin, and the purpose of a specification is to have a full and traceable origin of the materials. This would be the same worldwide, EN, JIS or any other code.

Trying to present your material with only 'part of' the origin could in my opinion in worst case lead to commercial and juridical consequences.

Your material will have to be presented just as you describe it: A479 grade 316 austenitic cylindrical hot rolled bar (material certificate no) machined and according to ASTM A182, A788 paragraph 6.4.2.

Or have I missed something?

 

[phazzevi]

In general i agree with you, and this is also the way i apply actually. In this special case the problem is that a rolled bar will never be a forgings according to A788 (A788 exludes this possibiliy), so i don't understand why a meterial specification says that in some cases i can obtain a forgings starting from a rolled bar.
I attach the standard text.

6.4 The material shall be forged as close as practicable to
the specified shape and size.
6.4.1 Flanges of any type, elbows, return bends, tees, and
header tees shall not be machined directly from bar stock.
6.4.2 Cylindrically-shaped parts may be machined from
forged or rolled solution-annealed austenitic stainless steel bar
without additional hot working.
6.4.3 Small cylindrically-shaped low alloy and martensitic
stainless steel parts, NPS-4 [DN 100] and under, may be
machined from forged or rolled bar, without additional hot
working.
6.5 Except as provided for in 6.4, the finished product shall
be a forging as defined in the Terminology section of Specification
A788/A788M.

 

[gerhardl]

Hello phazzevi, what if we look at it this way:

1. All valve material specifications (worldwide- any rules) are set down in such a way as to describe a certain material quality (not less than) for the complete valve.

2. Practical adaptions as for instance not to rule out already existing and proven and tested valves on the market, or to make alternative use of material where this is possible of practical, economical or other reasons without lowering the (aimed for) quality level, will be incorporated and likewise included in the specification text.

3.The descriptions cited by you seems straightforward and clear to me: rolled bar (not forged) is described as an exception for certain parts under certain circumstances.

As a result you should in my opinion be able to use this alternative, with reference, as my first post, to a description of what exact material this is and to paragraphs describing the exception.

(If two materials are described as interchangeable for practical use, they are so, but they do not change names, black is black and white is white!)