Wrong PWHT Procedure Applied?

[Jason123456789]

I have a carbon steel valve with flanges welded one and the wrong heat treat procedure applied to it. The heat treat procedure used holds the temperature at 1550-1650 F for 45 minutes then removed and quenched in oil, until cool. The parts are then tempered in 1000 - 1200 f range for 2 hours to obtain hardness of Rc 28-36.

The correct procedure places the components in a furnace at 800 F, and increased to 1100-1200 f for 15 minutes per inch of weld thickness. After reaching 800, it is cooled in still air.

Is there something I can do, or should the part be scrapped.

Thanks!

 

[metengr]

You have a nonconformance. Did you obtain portable hardness values to confirm the hardness range you stated? You have basically normalized with liquid quench and tempered the carbon steel. This may be an acceptable heat treatment for service, but this depends on the service conditions. If you need a lower hardness, you can re-temper at 1200 deg F/inch of thickness for the thickness involved.

If the measured hardness is acceptable with the client, I would perform a surface NDT to ensure no cracks and report that the carbon steel valve and flanges were subjected to a normalization with liquid quench and temper heat treatment. The 1000 deg F temper is lower than I would like to see, but this is why I suggested obtaining hardness data to corroborate your assumption.

 

[weldstan]

Assuming that the part could be used, you would also need to requalify the WPS with the PWHT preformed.