High operating temperature of ASTM A 333 Gr. 6, aging (hardening) and loss of toughness/ductility?

[EstebanR]

This is a low temperature carbon steel used for applications down to -50 F as per ASME B 31.3. But what is the highest temperature in which this material can be safely used, in piping, especially considering ageing or aging, which can cause a loss in toughness/ductility? Is this material prone to suffer from this, what conditions would cause it, and can it be prevented?
I see that this material is used a lot up to 200 C, yet I have also heard about loss of toughness because of hardening at temperatures over 150 C.
Thanks in advance for the insight, references and comments.

 

[JackLeeKH3]

Hi EstebanR,

The highest temperature of A333 Gr6 can be safely used are much depending the design condition i.e. design pressure & design temperature. You may using the wall thickness calculation formula to determine how high temperature you can go with your selected pipe schedule. Note: The higher temperature, the lower the material stress.

For an example, your design condition is 90 barg and 35 DegC, Sch40 pipe 4" (with 1.5mm C.A.) - safe to use.
However, when you increase temperature to higher, let say 250 DegC - then it is not safe to use, because higher temperature has weaker the material. At this case, you need thicker pipe, like Sch80, - then it is safe to use.

If I not mistaken, whenever there is high pressure and high temperature happened than what the pipe is designed for, it can cause a loss in its toughness/ductility.

Just my 2 cents. Thank you.

 

[XL83NL]

B31.3 stress allowables for A333-6 go up to, I think, 600 C. I wouldnt want to use it for that temperature though.
I believe these carbon grades would be limited to 400, max 425 C. Also, read the title of the ASTM A333 spec. And then compare to A106.

Also refer to B31.3 para F323.4(b) and ASME Sect II-D, non-mand. app. A.

 

[weldstan]

At 200C operating temperature, A333-6 properties will not be adversely affected.

 

[EstebanR]

Thanks for the replies. I got my hands around a bunch of articles that I need to go through. We will see if something interesting comes up regarding ageing of the material.

JackLeeKH3
Yeah, steels will lose strength with temperature and so the allowables will be smaller. I am more interested in what happens when the material ages - loses ductility - as a result of being cold-worked or exposed to a certain temperature for a long period of time. What conditions could yield this loss in toughness; what treatments, heat, elements could help prevent it.

XL83NL
Thanks. I checked that appendix of ASME B31.3 and it didn't say anything about ageing, so it seems like it is not a big concern.

Weldstan
Thanks for the input. I think maybe you are right and it does not seem like it will be trouble.

 

[XL83NL]

I guess I didnt the read OP's 1st post good enough. At 200 deg C I wouldnt be concerned about it