Decoding material specifications

[ehilge]

Hello,
I've been trying to learn exactly how materials are specified, with particular reference to pipes and fittings, and I've come across some conflicting information and apparent confusion. The callouts I've been coming across have an ASTM #, grade #, amd sometimes a UNS#.

For example: ASTM A403 Grade WP316 (UNS S31600)

I'm fairly certain the ASTM number specifies the actual material composition and the minimum alowable mechanical properties, like tensile strength and yield strength. Does the ASTM number actually mean anything itself? i.e. does the 'A' or the fact its in the 400s indicate anything in particular about the material.

From what I can tell, the grade has more to do with the finish or how it is manufactured. I found that WP indicates wrought in this case. Again, does the number itself mean anything?

I have the most confusion with the UNS number. I can't tell if its just a different was to specify the same thing or if it adds more description to what has already been listed.

Any light you can shed on this subject would be most appreciated, thanks in advance for your help.

 

[Mech_Engineer]

UNS number (Unified Numbering System) is a unique alloy identifier which provides the material composition. See here: http://en.wikipedia.org/wiki/Unified_numbering_system. This is just raw material data, it has no requirements for manufacturing, heat treats, post-work, strength, etc.

I don't have the spec in front of me, but it seems the ASTM specification deals with how to manufacture, test and rate stainless steel pipe fittings using stainless steels such as S31600 (stainless steel 316, which is a high-corrosion resistance steel).

Does that help?

 

[Travis_King]

The ASTM 403 indicates that this is for wrought fittings.
The Grade WP316 indicates that it is Standard [i.e. not LowCarbon (316-L) or High-Temp (316-H)]
Mech_Engineer told you what UNS was.

The UNS number is simply for reference if that is how a company references materials (say, in a different country). For example, you have your Standard 316 Stainless Steel, which is S31600, and you have Low Carbon 316 Stainless Steel, which is S31603. These can also be referenced as WP316 and WP316-L, respectively.

ASTM stands for the American Society for Testing and Materials.
See HERE

See HERE for the abstract of the ASTM A403 standard.

http://www.sunbeltsupply.com/docs/ASTM%20Materials%20Cross%20Reference%20Chart.pdf is a resource for ASTM material specifications data

Also, see page 68/77 of THIS for typical information that comes along with the spec you referenced.

 

[ehilge]

Thanks for the information. Is there anything akin to standard rules for the numbering systems? Or are the numbers purely arbitrary? For example, if an ASTM number is in the 400 range, does that in itself give you any particular information on the item in questions?

 

[Travis_King]

It's the section in the ASTM standard.