Regarding Impact testing of Duplex SS Material

[ashaykadam]

I have a query regarding Impact Testing of Duplex SS Material.

As per ASME Section VIII Div. 1, Clause UHA-51(d)(3) Impact testing is exempted for Duplex SS as follows:

for the following steels in all product forms at MDMTs of −20°F (−29°C) and warmer:
(a) austenitic ferritic duplex steels with a nominal material thickness of 3⁄8 in. (10 mm) and thinner;

Does than mean,
1. Duplex SS having MDMT less than -29°C requires irrespective of thickness?
2. Duplex SS having (any) MDMT warmer than -29°C requires Impact testing irrespective of Thickness? Suppose take an example of MDMT 25°C. Will it call Impact Testing for any thickness?

 

[fegenbush]

I can understand question 1, but I am not certain from where question 2 comes.

1. Duplex SS having MDMT less than -29°C requires irrespective of thickness?

- Yes.

2. Duplex SS having (any) MDMT warmer than -29°C requires Impact testing irrespective of Thickness? Suppose take an example of MDMT 25°C. Will it call Impact Testing for any thickness?

- No. Impact testing for MDMT > -29°C is only required for materials having a thickness greater than 10 mm.

 

[SnTMan]

ashaykadam, 1) Yes
2) No, thickness 3/8" and less can be exempted
For your exmaple, see 2) above.

Regards,

Mike

 

[ashaykadam]

Thansk for your reply.

Sorry. I think some typographical error in my question 2.
I will reform my question 2. as follows:

2. Duplex SS having MDMT warmer than -29°C requires Impact testing (for thickness more than 10 mm) irrespective of MDMT?
Suppose my MDMT is 25°C or say 300°C. Will in that case aslo Duplex SS have to be Impact Tested?

 

[SnTMan]

ashaykadam, by my reading of the Code, I'd still say yes, if thickness exceeds 3/8.

I will say an MDMT of 300 C would be unusual

Regards,

Mike

 

[ashaykadam]

Thanks all.

Yes. I also agree.

I just put that as an example.

Was really surprised that Austenitic SS can be exempted from Impact Testing for MDMTs warmer than -198°C.

Wheras Duplex SS (Austenitic & Ferritic) have to be impact Tested irrespective of MDMT if thickness exceeds 10 mm.

Thanks anyway.
Have a Nice Day!

 

[SnTMan]

ashaykadam, see 6.2.3 of the attached for some insight.

Regards,

Mike

 

[ashaykadam]

Thanks Mike.

 

[fegenbush]

Mike,

I would advise against attaching copyrighted material no matter how helpful.

 

[ashaykadam]

No problem of copyrights as fasr as this attachment is concerned.

It is available for free download at below URL:

http://www.imoa.info/download_files/stainless-steel/Duplex_Stainless_Steel_2d_Edition.pdf

 

[SnTMan]

fegenbush, you are correct, of course, however I did get it at the link noted by ashaykadam.

 

[pradipgoswami]

Hi Ashaykadam,

A description of the grades to be welded would have been more meaningful.What's the duplex grade to be welded, Duplex-31803/32205 or super duplex UNS-32750/32760.

The ASME Section VIII requirements for impact testing for DSS base and weld metals are given in UHA-51(d)(3). They require impact testing of all DSS thicker than 10 mm (3/8 in.) or those with an MDMT less than –29 °C (–20 °F).

For a design temperature above -29Deg C, strictly ASME Sec-VIII, DIV-1 does not require impact test. However if the design specifications of any of the oil and gas majors are applicable impact test is mandatory (say like Shell-EP 61.40.20.31). For duplex/ and super duplex (especialliy super duplex) impact test is one way of determining the sensitivity of the steel to imtermetallic formation. See ASTM A923, method B for guidence.

Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario, Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299