Normalizing 1

[weldtek]

Is there a specific ASME Code requirement for time at temperature? I'm aware that normalizing is typically performed at 100 F above the upper critical temperature, but, is there a specific requirement for the time it is held at that temperature.

 

[metengr]

weldtek;
For conventional heating of components, the soak time is typically 1 hour per inch of material thickness to allow for uniform heating (in cases of post weld heat treatment, the Code is clear on this issue) and to allow for phase transformation kinetics to complete during austenitizing (annealing or normalizing).

The one hour inch of material thickness has been used for many years by heat treaters and boiler/pressure vessel fab shops, which as a practice, made its way into most Standards and Codes.

 

[weldtek]

Metengr,
Thanks for the quick response. I've seen some MTR's that show as little as 30 mins/ inch and, and others that show longer hold times. The material specification and SA 20 both lack specific hold time requirements for normalizing. Metals Handbook has suggestions for annealing times but not for normalizing. As you say, the Code is specific with regard to hold times for SR, but, I guess in the case of normalizing, industry standards prevail.