SA-105 Material_ MDMT -20°F 1

[Mechanical1991]

Hi all,
I have a question about SA-105 material
According to ASME VIII Div 1 2019, the SA-105 material belongs to Curve A (before it belonged to curve B), which does not reach up to -20°F MDMT. Can I apply Figure UCS-66.1 to reduce the temperature to reach MDMT -20°F?

Thanks for your comments

 

[Cobra17]

you can use UCS-66(b)(1)(-b) stress ratio to reduce it per UCS-66(b)(3)

 

[Mechanical1991]

Thanks Cobra 17,
Now I understand, ASME VIII 2019 UCS-66(b)(1)(-b) still allows temperature reduction to be applied to flanges under the consideration that it is a "components
not stressed in general primary membrane tensile stress, such as flat heads, covers, tubesheets, and flanges"

But is it advisable to apply these temperature reductions???? since SA-105 is currently located on the curve A for some reason.

 

[Cobra17]

SA-105 is only located on curve A if it doesn't meet UCS-66(c)(1)(-a), assuming it's a flange

(1) ASME B16.5, ASME B16.47, and long weld neck
forged flanges:
(-a) when produced to fine-grain practice and
supplied in the heat-treated condition (normalized, normalized
and tempered, or quenched and tempered after
forging) and used at design temperatures not colder than
–20°F (–29°C)
(-b) when supplied in the as-forged condition and
used at design temperatures not colder than 0°F (–18°C).

If they do meet (-a), then they are curve B per figure UCS-66.

(2) Curve B applies to the following:
(a) see below:
A/SA-105 forged flanges produced to fine grain practice and normalized, normalized and tempered, or quenched and tempered after
forging


If you are talking about a coupling or something like that, then it can be a Curve B per figure UCS-66 Note (2)(c)

(c) all pipe, fittings, forgings and tubing not listed for Curves C and D below

 

[Mechanical1991]

You are right Cobra 17.
In my case, I am talking about a Flange SA-105 (Curve A), then the minimum design temperature is 0°F.
My question was if it is possible to apply the temperature reduction for the sa-105 (only) flanges and thus be able to obtain MDMT -20F?

Thanks!!

 

[Morcuse]

To your question: yes, it is possible to reduce UCS-66(c) with the corresponding ratio in UCS-66(b)(1)(-b).

Is it advisable? You need to use your engineering judgement here.

 

[Mechanical1991]

Thanks Morcuse for your input. All answers are very helpful.