See ASME 1 A-101.2 For thicknesses of 2 in. (50 mm) or greater,
the following rates of heating and cooling should be
applied; however, these rates should not be applied to
P-No. 7 and P-No. 10I welded base materials:
(a) Above 800°F (425°C), the heating rate should not
exceed 600°F/hr (335°C/h) divided by the thickness in
inches (in millimeters, the thickness divided by 25
shall be used), but in no case should it be more than
600°F/hr (335°C/h).
(b) Above 800°F (425°C), the cooling rate should not
exceed 600°F/hr (335°C/h) divided by the thickness in
inches (in millimeters, the thickness divided by 25
shall be used), but in no case should it be more than
600°F/hr (335°C/h).
(c) The rates of heating and cooling need not be less
than 100°F/hr (55°C/h).
From 800°F (425°C) or below, the pressure part should
be cooled in still air.

Regards

Thank you r6155.

I did se A-101 but that only mentioned 50mm and above material thickness. what if the base material is under 50mm like in my example where the base material is 25mm then do you half the cool/heating rate?

cheers.

Please, read (slowly) A-101.

Regards

It isn't fair to chastise someone (even passive aggressively) when you give them a Code paragraph that clearly states 2" or greater. At least reference PW-39.3 that leads to A-101.

@ david339933
You are some confused. ASME 1 A-101 is very clear for all thickness.

Regards

Haha ok ok 25mm / 25 =1
355 / 1 = 355C/hour

Just the first line of A-101 “for thickness 2” or great”

All thanks for that. Be working as a welder for 12 years been given a roll as welding inspectors a few weeks ago. And just trying to learn as much as I can about all aspects of the codes / standards
Cheers

@ OZWelder
You need to consider A-101.1 (not A-101.2)
Good information in WRC 452 Bulletin "Recommended practices for local heating of welds in pressure vessels"

Regards

See more here.
Interpretation Detail
Standard Designation: BPV Section I
Edition/Addenda:
Para./Fig./Table No:
Subject Description: PW-39, Heating and Cooling Rate for PWHT
Date Issued: 09/09/1981
Record Number: BC-81-154
Interpretation Number : I-81-24
Question(s) and Reply(ies): Question: In PW-39.3, it is mentioned that weldments shall be
heated slowly to the PWHT temperature as recommended in
Table PW-39. What is the recommended rate of heating and
cooling?
Reply: Section I avoids defining specific limits for heating and
cooling rates because of the very wide range of thicknesses
which may be encountered. The principal concern implied by
the word "slowly" is that when different thicknesses of material
are being heated or cooled together, too fast a rate of
temperature change may cause distortion by the differential
rate of temperature change, and the differences in metal
temperature, between the thick and thin sections.

Regards

@6155

Thank you very much for your assistance