SA-516 60 & SA-516 70 simultaneously 3

[Paulettaa]

Dear all

A supplier of carbon steel plates says that the product conforms to both SA-516 60 & SA-516 70. Am I allowed to consider the allowable stress to be that of SA-516 70 and for UCS-66 consider the exemption curve to be that of SA-516 60 in the design of the same equipment as per VIII-1. If yes where can I find a reference to this issue in ASME BPVC VIII-1 or in ASME BPVC II ?

Regards

 

[marty007]

No. Once you make a selection to use the properties of one grade, the material must then be treated as that grade alone for all other physical property and code rule design aspects.

See ASME IID - Appendix 7-240

 

However, dual certified steel can be useful in welding procedure qualification.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

 

[Paulettaa]

Thank you marty007. That was completely to the point.

Actually I was thinking about the meaning of the temperatures listed in Table A2.15 of SA-20 ASME BPVC Sec.II-A. In this table for SA-516 grade 60 and a shell thickness of 60 mm, the impact test temperature is -46 C. However, that temperature for SA-516 grade 70 is mentioned to be -35 C. In my calculations of thickness I took the plate to be SA-516 70 however the MDMT is -45 C. Then I thought this multiple certified plates may be a solution. I want to know if these plates are impact tested are they impact tested in the lower temperature?

And a more general question is that what is the meaning of the mentioned temperatures in the table A2.15? Does it mean that if I choose a lower temperature for the impact test I have violated any requirements of the code? or it simply says that the possibility of a brittle fracture is much higher below these temperatures?

Regards

 

[SJones]

See the text of SA-20, 12.1.5.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[marty007]

SJones is spot on.

Just for information, in my area we can find pretty well any thickness of SA-516-70 plate tested to -50°F. That appears to be the standard around here.

 

[Paulettaa]

Thank you for your replies.

I noticed in the specification of SA-516 that the tensile strength has both minimum and maximum values rather than just a minimum.

First, I want to know why there is an upper limit for the tensile strength since it seems to be a beneficial property.
I mean if the tensile strength is 563 MPa, is it not OK to certify the material as SA-516 60? A laboratory has rejected our materials both for chemical and mechanical test results.
The reason for rejecting it mechanically is that its tensile strength is 563 MPa which is more than the upper limit on the tensile strength. The average value of the impact test is 217 J and the yield strength is 415 MPa these values are both well above the minimum requirement.

For the case of the chemical rejection they have mentioned that the chromium content is 0.38%. I found it in SA-20 Table 1. Based on this table this material cannot be any of SA-516 grades.
What happens if the chromium content is higher than that mentioned in this table? does it result in welding difficulties?

Regards

 

[r6155]

1)The laboratory is correct.
2)Check with original manufacturer’s test report
3)Talk to the plate supplier

Regards
r6155

 

[weldstan]

The purchaser must specify impact testing requirements for SA-516. It is readily available from stockists with impacts at -50F, although not with 217 Joules as a minimum. On e can also direct order from the mill.