A53 Gr. B pipe hardness 1

[Mous1747]

I’m my plant we have a A53 GR. B pipe that was designed for max temp of 750F as per B31.3

However this pipe was exposed to 950F for almost 10 hours

The pipe didn’t fail or anything but we are concerned that the hardness gone above the limits

Is there max hardness allowed for this pipe that we shouldn’t go above?

 

[weldstan]

Hardness will not be increased.

 

[Mous1747]

Weldstan, thanks for your reply can you direct me to a reference ?
I looked at the ASTM standard specification for A53 but there was no mention of hardness
So I’m not sure where can I find more information

 

[weldstan]

The temperature will have to exceed the lower critical followed by rapid cooling to have a potential for increased harness. Your temp is well below the lower critical temperature and the time at temp will actually lower the at room temperature hardness.

The ASM Metals Handbooks amongst other texts provide info in this regard. I have also had experience hardness testing of low carbon steel piping experiencing similar upsets.

 

[Mous1747]

so just to clarify it would be fair to say that any cooling rate from temperatures below A1 results in the same
microstructure and hardness?

 

[CWEng]

Yes, but not the same residual stresses.