Table 131.1.3

[Fizza453]

Dear Code Users,

Is it correct that as per 2014 Edition of B31.3, For P-No.1 materials PWHT is not required for all thicknesses (even if control thickness is over 38 mm) provided that a preheat of 95C is applied (for nominal thickness over 25 mm )and multiple layer welds are employed (for nominal thickness over 5 mm) ?



Javed Nasir
Inspection Engineer
Technip-France Abu Dhabi

 

[pradipgoswami]

Hi Javed,

Pleases refer Table 331.1.3 Exemptions to Mandatory Postweld Heat Treatment

In addition to the rationale put forth by you please note the additional requirements as below should be considered for waiving PWHT. The highlighted clause is also to be considered while not considering PWHT and that's important in the context of B-31.3.
B 31.3 design & operating conditions involves severe possibilities of EAC(e.g. Stress Corrosion Cracking), where hardness & resultant residual stress is the major contribution factor. Hence while waiving PWHT it's advisable to consider all the applicable clauses.

(2) The control thickness is defined in para. 331.1.3.
(3) The nominal material thickness is defined in para. 331.1.3(c).
([highlight #FCE94F]4) No exemptions are permitted for PWHTs required by the designer or the WPS.[/highlight]
(5) Additional exemptions for welds made in accordance with para. 328.7 may be taken for the materials addressed.

Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299

 

[Fizza453]

Dear Pradip,

Thanks for your valuable comments.
Say PWHT is not required due to Point No 4.
AS I understand PWHT is not required even control thickness is over 38 mm provided that preheat is applied as required by Table 331.1.3. Do you agree?
If it is so, it looks strange when compared with Section I, VIII-1, VIII-2, B31.8.



Javed Nasir
Inspection Engineer
Technip-France Abu Dhabi

 

[pradipgoswami]

Hi Javed,
Clause No 4 is a waiver, it makes PWHT as mandatory.
My thoughts are this waiver is not general all across the board. If required in B-31.3 design,F323.4 Specific Material Considerations — Metals needs to be looked into.
Moreover if NACE or API RP's is specified in design , such as MR0175 or MR0103 and RP0472, waiver of PWHT gets difficult.
It would be good to know:- the design requirements, process fluids, operating requirements. and application of API, NACE clauses as above.
Everything should be considered before providing waiver of PWHT.
Thanks.

Pradip Goswami,P.Eng.IWE
Welding & Metallurgical Specialist
Ontario,Canada.
ca.linkedin.com/pub/pradip-goswami/5/985/299

 

[metengr]

Yes, PWHT is not required. If the WPS requires
PWHT or it is specified by contract you PWHT.

 

[Fizza453]

Dear Pradip,

agreed with you that there are many process concerns, stress corrosion cracking concerns etc.
Say if none of them is applicable. To make the question simple and straight forward, only Table 331.1.3 is a concern.
Is it correct that 40 mm control thickness (P-No.1 Group No.1) is exempted from PWHT provided that preheat of 95C is applied? As I read Table 331.1.3, it is exempted. Please give your feedback. Thanks.

Javed Nasir
Inspection Engineer
Technip-France Abu Dhabi

 

[david339933]

Correct.