Material Double Certified

[Simdro]

Dear All,

I'm checking the Vendor Documents for a Big Vessel which should be had the shell courses and other welded parts in contact with the process fluid made by SS Tp316L as specified into the Client Mechanical Data Sheet.
The proposed Material by Vendor is double certified Material SA-240 Tp316/316L.
Therefore he had used into the calculation the mechanical properties (e.g.:Allowable Stresses, Yield, etc) of Tp316 and, at the same time, he had also declared the chemical properties of Tp316L.
The Vessel is designed in accordance with ASME VIII Div.1.
Can the applicable code accept to perform the Mechanical Calculation using the better Strenght Characteristc of Tp.316?

I don't know if I got it across.

 

[CodeRef]

This has been discussed here before. Search the posts using the keywords "Dual Certified 316L" and read the results.

If occuring after Construction and Stamping, please contact the jurisdiction of installation for guidance as this could result in a Rerating/Alteration.

Also, see the following interpretation

Subject: Section VIII, Division 1 (1992 Edition, 1992 Addenda); Reference to Dual Marked Material in Manufacturer's Data Report Forms

Date Issued: September 29, 1993
File: BC93-399

Question(1): May a dual stenciled material (e.g., SA-240 304/304L) be listed as SA-240 304, SA-240 304L, or SA-240 304/304L in the Manufacturer's Data Report Forms when using only one set of design allowables for the particular Grade designation?

Reply (1): No, the material shall be listed as the material grade chosen from the allowable stress tables.

Question (2): If the dual stenciled material is listed as SA-240 304, may the "Remarks" section of the Manufacturer's Data Report Form contain the phrase " The shelf and bottom head material meet all the requirements of SA-240 304 and SA-240 304L"?

Reply (2): Yes.

 

[vesselfab]

We use the higher stress level of the 304 or 316 material in our data book and calculations.

the client is happy because it says 304l or 316l for chemistry.

have not run into anyone that would not accept this.

 

[jte]

Simdro-

As vesselfab indicated, you are essentially trying to please two masters. There is no probibition for you using the "straight" grade material for all of you Code calc's. Keeps us stress geeks happy and complies with Code requirements. In addition, and entirely separately, you need to please your client's materials engineer. As far as the materials engineer is concerned, you're using the "L" grade material. Just don't mention the "L" in your Code documentation, except as noted in Question 2 of the Interpretation CodeJackal provided above.

If you're investigating this issue, please also consider "Optional" Appendix 7 in II-D "mandatory."

jt