Minimum Design Temperature without Impact testing for ASTM A 182 F51 1

[paavainathan]

Dear all,
what is minimum design temperature without Impact testing for ASTM A 182 F 51 DSS Forging as per ASME B 31.3 .If i use this material in my valves upto design temperature minus 20 Deg C the material shall be impact tested or not? please clarify .

 

[metengr]

Since SA 182 Grade F51 has a stress line in ASME Section II, Part D, Table 1A, the minimum design metal temperature for this material with no impact testing is -20 deg F (-29 deg C).

 

[rneill]

Interesting, I had never noticed before that the duplex forgings don't seem to be listed in Table A-1 of B31.3 (or at least my 2006 Copy).

ASTM A790 Grade 31803 pipe is listed and has a min temperature of -60 F and perhaps we could assume that value for the F51 forgings as F51 has the same UNS designation?

 

[SJones]

They are still not specifically listed in the 2008 version either which probably then invokes clause 323.2.4 which would then lead on to what constitutes 'qualification' of low temperature toughness. In my view, it means Charpy test at -20 deg C. Others may see it as simply referring to ASME II, or getting some lab data from the alloy supplier. No doubt that somebody who has had to go through the experience can provide enlightenment of the process.

Steve Jones
Materials & Corrosion Engineer

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

 

[metengr]

If i use this material in my valves upto design temperature minus 20 Deg C the material shall be impact tested or not? please clarify .

Let me clarify. If you have ASME B31.3, specifically review section 323.2.2 and Table 323.2.2 and finally 323.2.3. Regarding duplex stainless steels, they are mentioned in Material category A-3 of Table 323.2.2 along with other carbon and high alloy ferritic steels, etc.

Since this grade of duplex stainless steel is not listed in Table A-1 specifically, but is mentioned in row A-3, see column B of Table 323.2.2, Notes 3 and 5. Note 3 pertains to not having to conduct impact testing at or above -20 deg F (-29 deg C).

Again, as I mentioned above, this material has a stress line published in ASME Section II with a stated minimum design metal temperature, which meets the requirement in 323.2.3 for unlisted material and subsequently meets 323.2.4 for verification of serviceability. Therefore, no impact testing is required at or above -20 deg F (-29 deg C).

 

[rneill]

In reviewing Table 323.2.2, I take the F51 material to be an unlisted material since it does not appear in Table A-1.

My reading of Table 323.2.2 is that rows 1 to 6 apply specifically to listed materials. The general reference to Duplex in row 3 would be a reference to the listed grades of Duplex. Since F51 is not a listed material, it would be addressed in row 7 as an unlisted material.

According to row 7 of this table, where an unlisted material is comparable to a listed material, the requirements for the listed material shall be met. It then suggests that other unlisted materials (i.e., those that are not comparable to a currently listed material) shall be qualified per Column B.

In this case, since F51 material is comparable to A790 Grade S31803 material, and Table A-1 lists the A790 Grade S31803 material as suitable to -60 F, I would take it that we could apply this limit to the F51 material as well?

 

[SJones]

Like I said: there will be discussion as to what constitutes 'qualification.' I would tend to go along with rneill's reading of Table 323.2.2 but would have to baulk at considering a valve forging as a comparable product form to a pipe or tube.


Personally, I would have it all Charpy tested anyway just to make sure those nasty phases weren't present; but, then again, I'm not the manufacturer with the risk of failure.

Steve Jones
Materials & Corrosion Engineer

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

 

[paavainathan]

Thanks a lot for all your efforts and inputs.
As said by rneill & Sjones for a unlisted material we can compare with an equivalent listed material provided chemical,mechanical properties,heat treatment,method of manufacturing are same as per 302.2.3 of ASME B 31.3.

In our case the A 182 F51 UNS S31803 is a forging of DSS .In case of A790 UNS 31803 is a pipe of DSS.
I hope there are some difference in manufacturing process though the chemical compositions are same.In this context is it acceptable to compare and take 60Deg F as minimum design temperature?

 

[rneill]

As SJones points out the answer is not clear ... While the metallurgical properties are similar, the product forms themselves are not similar.

I'm not sure about the fact it has a stress line in ASME Section II necessarily making the limit -20 F since Table 1A shows -20 F as the min temperature for everything contained in the table and we know that Table A-1 of B31.3 certainly permits many of those materials to temperatures much lower than this without impact testing (including S31803 pipe material).

At this point, I think there is some latitude for the designer to use his judgement and expertise to make his own call on whether they deem the material/metallurgical properties of F51 to be comparable to S31803 pipe and thus whether they want to assign a minimum temperature of -60 F to the F51 or whether they want to specify impact testing.

You could always submit a code interpretation request but it would take some time to get an answer and I'm not sure it would be that much more helpful. However, perhaps it might stir the committee to consider adding these other Duplex materials to Table A-1 ?

I took a quick look and didn't notice any existing interpretations on the subject but my collection of interpretations is far from complete.

 

[metengr]

rneill, et al
The OP asked about -20 deg C, not below, regarding impact exemption for this material. With the stress line clearly stated in Section II, I believe this addresses the OP regarding service use considering the amount of testing required to have a stress line published in Table 1A of Section II. I agree there is confusion in B31.3. However, we were discussing about service use at or above -20 deg C, not below.

 

[SJones]

The first sentence of the OP actually asks for the minimum design temperature without impact testing. The second sentence then mentions a specific application at -20 deg C. In answering the former, rneill et al are also trying to cover the latter.

Steve Jones
Materials & Corrosion Engineer

http://www.oilandgaspeople.com/cv/11499664

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