Discordance between B31.1 and Sec.8 regarding Thickness for PWHT

Question

Discordance between B31.1 and Sec.8 regarding Thickness for PWHT

Newbie2211 (Mechanical)

(OP)

12 Jun 23 08:07

Hi guys!
I found discordance between B31.1 Table 132.1.1-1 and ASME BPVC Sec.8 UCS-56, So I ask you which one should apply.

In Table 132.1.1-1 of B31.1 2018 Ed., control thickness is criterion for PWHT.

But in UCS-56 of ASME BPVC Sec.8 2021 Ed., nominal thickness is criterion for PWHT.
And for P-15E, "Weld Thickness(Nominal)" is criterion for PWHT.

I'm so confused because those two thickness are different.
Could you tell me which one is correct?

DekDee (Petroleum) · Answer 1 · 2023-06-12 09:35:32

One is a Pressure Piping Code and one is a Pressure Vessel code.
If you are dealing with something you feel may be a Pressure vessel and a Pressure pipe then feel free to ask for clarification.
Otherwise, please use a bit of logic.

r6155 (Mechanical) · Answer 2 · 2023-06-12 12:16:25

@ Newbie2211
ASME B31.1 2018 is old. See 2022 ed and read again

Regards

Newbie2211 (Mechanical) · Answer 3 · 2023-06-12 23:03:16

@DekDee

Thank you for your kind reply.
We typically use B31.1 rather than BPVC Sec.8, so I think I need to apply B31.1.

Thanks.

Newbie2211 (Mechanical) · Answer 4 · 2023-06-12 23:05:06

@r6155

In B31.1 2022 Ed., control thickness is criterion for PWHT too.

r6155 (Mechanical) · Answer 5 · 2023-06-13 12:15:36

@ Newbie2211
Thickness is always the way to go for PWHT for most materials. B31.1 and VIII are the same concept, no discordance.
There are other reasons for needing a PWHT.
I told you B31.1 2022 because it is the current edition.

Regards

Cobra17 (Mechanical) · Answer 6 · 2023-06-13 16:25:54

I want to know why Table UCS-66 and 323.2.2A have different values.

Geoff13 (Structural) · Answer 7 · 2023-06-14 14:11:04

Each Code has different :

Types of products covered
Factors of safety
Authors
History
Consequences of failure
Etc
Etc

Thus I would expect B31.1 and Sect VIII Div 1 to have different requirements.

Use the Code applicable to the product you are designing, and ignore other Codes.

SnTMan (Mechanical) · Answer 8 · 2023-06-14 14:59:15

In addition, different committees formulate the rules for the different Codes.

Regards,

Mike

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Discordance between B31.1 and Sec.8 regarding Thickness for PWHT