Materials & Welding: Re: [MW:30211] ASME B31.3 PWHT

Tuesday, November 5, 2019

Re: [MW:30211] ASME B31.3 PWHT

Dear Sirs,

Thanks for your support.

Question: Preheat of > 95C (200F) is not used but the weld is made with multiple passes. Is PWHT required for a weld joining P-No.1 materials, when the control thickness is less than or equal to 25 mm (1 inch) but the nominal material thickness is greater than 25 mm (1 inch)?

Answer: Since weld is made with multiple pass so PWHT is not required for P-No-1 materials.

Reply ==> Since the exemption shall be based on nominal thickness. I understand that this case (see attached picture) PWHT is required ( because nominal material thickness is greater than 25 mm (1 inch) -& preheat 95 deg C not applied ). Please correct me if I am wrong. Thank you.

Could you please advise me: which thickness, Control thickness or Norminal material thickness, shall be used to determine PWHT requirements & exemptions as per ASME B31.3 ?

Answer: Its control thickness which decides the requirement of PWHT but the exemption shall be based on nominal thickness. Here for P-No.1 , for all control thickness its exempted subjected to the requirements of Column 4 of Table 331.1.3 c is met. Similarly for P=no.3 materials PWHT is must for control thickness greater than 16mm but for lesser thickness it can be exempted subjected to the requirements of table 331.1.3.

Vào Th 3, 5 thg 11, 2019 vào lúc 14:24 atul khatri <atul.mnnit@gmail.com> đã viết:

Question: Preheat of > 95C (200F) is not used but the weld is made with multiple passes. Is PWHT required for a weld joining P-No.1 materials, when the control thickness is less than or equal to 25 mm (1 inch) but the nominal material thickness is greater than 25 mm (1 inch)?
Answer: Since weld is made with multiple pass so PWHT is not required for P-No-1 materials.

Could you please advise me: which thickness, Control thickness or Norminal material thickness, shall be used to determine PWHT requirements & exemptions as per ASME B31.3 ?

Answer: Its control thickness which decides the requirement of PWHT but the exemption shall be based on nominal thickness. Here for P-No.1 , for all control thickness its exempted subjected to the requirements of Column 4 of Table 331.1.3 c is met. Similarly for P=no.3 materials PWHT is must for control thickness greater than 16mm but for lesser thickness it can be exempted subjected to the requirements of table 331.1.3.

Regards,
Atul Khatri

On Tue, Nov 5, 2019 at 8:44 AM José Juan Jiménez Alejandro <jjjimeneza@gmail.com> wrote:

El lun., 4 nov. 2019 a las 5:14, anhtrangnghieng (<anhtrangnghieng@gmail.com>) escribió:
Dear Sir,

Please support me to clarify this subject.
Thanks in advance!

Vào 17:15, T.2, 4 Th11, 2019 atul khatri <atul.mnnit@gmail.com> đã viết:
Hi,
Do you still have some doubt on replies to your query dated 03-Aug having subject "Difference between Control thickness & nominal material thickness ( Para. 331.1.3(c)" ?

Thanks
Atul Khatri
"

On Mon, Nov 4, 2019 at 8:44 AM anhtrangnghieng <anhtrangnghieng@gmail.com> wrote:
Dear Experts,

Could you please advise me for the following questions:

Question: Preheat of > 95C (200F) is not used but the weld is made with multiple passes. Is PWHT required for a weld joining P-No.1 materials, when the control thickness is less than or equal to 25 mm (1 inch) but the nominal material thickness is greater than 25 mm (1 inch)?

Could you please advise me: which thickness, Control thickness or Norminal material thickness, shall be used to determine PWHT requirements & exemptions as per ASME B31.3 ?

Thank you in advance for any help you can provide.

Regards.
--
PV

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