Yield strength at higher temperature

Hi all,

I need your opinions on the matter of yield strength at higher temperature, over 1000'F, which are not listed in Table Y-1 of Part D, ASME SEC.II.
For example, what shall I do if I need yield strength of N06600(inconel 600) at 1100'F. Can I use extrapolation from table Y-1? Or can I use the value from the manufacturer's publication?
If I can use manufacturer(Special Metals)'s data, do I have something to do for getting approval by the owner?

Please share your experience about this situation.

Regards,

Hi,

As per UHX 13.3; Yield strength shall be taken from TableY-1 in Section-II, Part D. When a yield strength value is not listed in TableY-1, one may be obtained by using the procedure in UG-28(c) (2) Step3.

If not possible then ask the manufacturer (which is selected by your client) to provide you the values.

Hope this will help.

Regards,
R.K.

I suggest you to compare the yield strength values in ASME II D and in Special Metals' brochure for the elevated temperatures.

If they are the same you may need to check the strain value to consider. At limit temperatures the strain is almost uncontrollable. Check it with client and manufacturer for the purpose.

If the compared yield strength values are not the same and ASME considers the lower values for the same elevated temperature, I would not recommend to go further, you either change the material (if you can find better) or try to reduce the metal temperature that ASME accepts for the stress and the strain.

When you work in the creep range of the material and especially on the higher limit you need to take the strain into consideration. I don't have the code with me to direct you on the issue. But I think you understand correctly what I do talk about.

Thank you RK,

I saw method in UG-28(c)(2)Step3 is for pipe with D/t < 10. Can I still use it even if D /t > 10?


And Ibrahim,
Sy at 600'C is about 40ksi from the brochure. But this value is larger than min. yield strength of 35ksi at 70'F(21'C) from Table Y-1. That's my headache.

Hi Parky,

I think the value mention in UG-28 will be for D/t >= 10. I dont have the STD at this point, but you can recheck this.
For D/t<10 I guess there are equation mentioned in UG-28.

(I am not 100% sure but it should be in step 7 or Step 8).

Regards,
R.K.