Dear Support
I have defined a user material A671 CC65, which has temperature beyond the minimal value TEMPERATURE in the database. Rohr2 use the option LOW TEMPERATURE to get the allowable stress. when I run the calculation, I got the allowable stress is 62.5 MPa at the temperature -40 C for 12.5mm wallthickness of pipe, and several parts are overstressed. I think the allowable stress is very low, so I wonder if that is right?
Best regards
Low Temperature in ASME B31.3
- rohr2support
- Beiträge: 455
- Registriert: Mi 14. Sep 2011, 08:23
Re: Low Temperature in ASME B31.3
Hi
I think there is a confusion about the interpretation of the "allowable stresses".
If you are in the low temperature zone below the allowable of the material (Fig. 323.2.2A) you can either do impact testing or you can use the material without any additional test by reducing the allowable values using the reduction curve
from FIG 323.2.2B. So in other words you are using the material outside of specification but you can still use it.
In your case you have -40°C where 10°C is allowable (Curve A). So you go 50° below the limit.
The reduction factor for 50°C is 0.43 so you can only use 43% of the allowable stresses at 10°C
or you can do impact testing.
Best regards
Rohr2Support
I think there is a confusion about the interpretation of the "allowable stresses".
If you are in the low temperature zone below the allowable of the material (Fig. 323.2.2A) you can either do impact testing or you can use the material without any additional test by reducing the allowable values using the reduction curve
from FIG 323.2.2B. So in other words you are using the material outside of specification but you can still use it.
In your case you have -40°C where 10°C is allowable (Curve A). So you go 50° below the limit.
The reduction factor for 50°C is 0.43 so you can only use 43% of the allowable stresses at 10°C
or you can do impact testing.
Best regards
Rohr2Support
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- r2user
- Beiträge: 144
- Registriert: Mi 14. Sep 2011, 10:18
Re: Low Temperature in ASME B31.3
Hi Rohr2support
Thank you for your prompt response. I think it helps me a lot. The two figures are used for carbon steel material.
I want to ask a simple question, can we use that for A671 CC65?
Best regards
Thank you for your prompt response. I think it helps me a lot. The two figures are used for carbon steel material.
I want to ask a simple question, can we use that for A671 CC65?
Best regards
- rohr2support
- Beiträge: 455
- Registriert: Mi 14. Sep 2011, 08:23
Re: Low Temperature in ASME B31.3
Hi
The material A671 CC65 is listed in Table A1 as carbon steel with temperature curve B.
So my assumption of curve A was wrong.
You should use curve B of fig. 323.2.2.A and the allowable temperature for 12.5mm wall is about -28°C.
So the reduction factor from fig. 323.2.2.B should be taken at (40-28)=12° and is about 0.8 instead of 0.43.
You may need to update your material description by clicking on "Low temperatures" and change to curve B like this: Best regards
The material A671 CC65 is listed in Table A1 as carbon steel with temperature curve B.
So my assumption of curve A was wrong.
You should use curve B of fig. 323.2.2.A and the allowable temperature for 12.5mm wall is about -28°C.
So the reduction factor from fig. 323.2.2.B should be taken at (40-28)=12° and is about 0.8 instead of 0.43.
You may need to update your material description by clicking on "Low temperatures" and change to curve B like this: Best regards
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-
- Beiträge: 4
- Registriert: Sa 24. Sep 2011, 04:02
Re: Low Temperature in ASME B31.3
Hi Rick,
Yeah, I see it.
Thank you for your professional technology support.
Every time I talk with you about problems, I will learn some new technology knowledge.
it's very exciting.
weiyi duan
Yeah, I see it.
Thank you for your professional technology support.
Every time I talk with you about problems, I will learn some new technology knowledge.
it's very exciting.
weiyi duan