PWHT on tube to tubesheet welds 1

[bytejuice2]

I have a Waste Heat Boiler with water/steam 250°C shell side and gas 3490C tube side.
Tubes are A.106 Gr.B, tubesheet is P355NH EN10028.3 (like A.516.70)
Tubesheet are integral 26mm thick with bend radius.
tubes are 4" and are welded to tubesheet with a groove tipe 'J', full penetration.
The distance between center of tube holes is 156mm.
My question is:
When is mandatory the PWHT on welds on tube to tubesheets joints?

thanks - Bytejuice2

 

[metengr]

The requirements for PWHT are defined in accordance with the particular Standard or Code of construction for the boiler. For example you have EN standards (12952 for water tube boilers, 12953 for shell boilers, etc) and ASME Boiler and Pressure Vessel Code, Section I.

I am most familiar with Section I. If you review part PW-39, this is the section providing direction for PWHT. Table PW-39 provides the PWHT requirements for P-No 1 base material. Based on the clarifications and notes in this table, you will find that for tube-to-tubesheet welds of thickness less than 3/8", PWHT is not required provided a 200 deg F is used for tubesheet thicknesses greater than 3/4".

 

[maryam1]

base on ASME secI PW.39 when pressure parts of two different P No. groups are joind by welding , the postweld heat treatment temperature is controlled by the higher P number and when nonpreassure parts are welded to pressure parts , the postweld heat treatment temperature of the pressure parts shall control. I would like to know , what happen if the nonpressure parts have the higher p number.

 

[metengr]

Per PW-39.2, ...When nonpressure parts are welded to pressure parts, the PWHT of the pressure part shall control. This means that if the nonpressure part is a higher P-No and is welded to a pressure part with a lower P-No, the PWHT temperature of the weld joint shall be limited by the pressure part PWHT temperature range.

 

[maryam1]

thank you dear metenger for your good help,but in this situation what should we do about the heat treatment time?

 

[metengr]

Can you provide more information about what you are joining? The PWHT time is based on nominal thickness at the weld joint. You need to determine nominal thickness and follow the rules in PW-39 for the pressure part PWHT time and temperature requirements.