Re: ASME mechanical properties

On Nov 15, 2007, at 10:59 AM, Afshin wrote:

> Somebody sometimes is confused in this world (I meant myself).

This is for everyone, not just Afshin, although his post is the example.

The first thing to do when confronted with material specification issues is to read the spec. That may answer the question, and in any event you'll know something about what you're talking about.

If you're looking for material properties, for God's sake do a web search first. There are thousands of web sites that provide materials data and one of the best is <http://www.matls.com/>. Manufacturers frequently summarize materials properties for their products. You can also find corrosion information and some application info as well. ***But remember*** that on-line summaries or manufacturer's web sites are not definitive and not guaranteed--only the specification itself actually defines the requirements to be met. What you'll see on-line are usually 'typical' properties which should never be used for final design.

As said in countless posts, ASTM and ASME specs are copyrighted and are not on the web, but you may find summary information if you do a simple Google search. Use the summary information for preliminary work, but always, always, always get your own copy of the material spec you refer to before you get too far. That way you won't get any surprises when the material you think you've specified isn't available in the needed size or strength level.

If you're doing ASME Code work you are absolutely restricted to materials specified in the Code you're working to. These materials always carry an ASME SA- or SB- specification. Don't try to substitute ASTM specifications. The ASME Material specs are always developed from ASTM specifications but frequently are more restrictive than the corresponding ASTM spec. Moreover you won't have allowable stresses for a material that isn't covered in a given Code. AISI specs or UNS numbers are chemistry only--they're no good for Code design, except to help you locate a particular ASME specification.

When you ask a question, don't just ask for properties--give some indication of the service and the Code you're working to. Explain why you need the information and what you intend to do with it. Be specific--don't just ask for 'all the properties.' In the first place it's incredibly stupid to base a design on materials data you get from a complete stranger via e-mail. You've no guarantee that the responder knows what you're talking about or what he's talking about or that the source of his information is authoritative or reliable. Use what you hear as a guide, then do your own homework. In the second place it's rude as hell to expect someone else to do your research for you.

And by way of warning, requests for copies of any such specifications (or drawings, design, or engineering data) will be rejected at moderation time without explanation. The PipingDesign list isn't a clearing house for warez or copyright material, proprietary data or anything else that your moderators, in their wisdom, feel is inappropriate.

Christopher Wright P.E. |"They couldn't hit an elephant at chrisw@skypoint.com | this distance" (last words of Gen.

.......................................| John Sedgwick, Spotsylvania