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Clause 304.1.2 (a) of ASME B 31.3, (with t<D/6 )

Clause 304.1.2 (a) of ASME B 31.3, (with t<D/6 )

Clause 304.1.2 (a) of ASME B 31.3, (with t<D/6 )

Dear friend

As per Clause 304.1.2 (a) of ASME B 31.3, the formula is acceptable if (with t<D/6 )

Questions :
1)"t" is Calculated Design Thickness (Excluded 12.5% / C.A ) or nominal?
2)If nominal Thickness (SELECTED THICKNESS) Has been selected so that t>D/6, What will be the B31.3 rule?

real Case :
Client PMS ==>PIPE 6" A106 THK 30.12 mm====> D/6=168/6=28 mm===>30.12>28
Max THK as per B36.10 for 6" is XXS(21.95)

RE: Clause 304.1.2 (a) of ASME B 31.3, (with t<D/6 )

t does not include either the 12.5% under-tolerance or CA.

Standard Designation: B31.3
Para./Fig./Table No:
Subject Description: 304.1.2; Straight Pipe Under Internal Pressure
Date Issued: 05/31/1983
Record Number:
Interpretation Number : 2-11
Question(s) and Reply(ies):
Question: For the pressure design of straight pipe under internal pressure, in accordance with 304.1.2 of B31.3, what equations apply when t is less than D/6 and when t is equal to or greater than D/6?

Reply: When t is less than D/6, the minimum wall thickness for pressure design shall be based on Eq. 3a, 3b, or 3c. When t is equal to or greater than D/6, the Code does not require that a specific equation be used in design. If Eq. 3a is used for design, the correct value for Y is d/(d + D). As stated in 304.1.2(b), the design of high pressure heavy wall pipe requires special considerations, and the final design is the responsibility of the designer.

RE: Clause 304.1.2 (a) of ASME B 31.3, (with t<D/6 )

Wow. It’s been a long time since the code committee provided such a long, explaining reply to an interpretation!

- You never get what you expect, you only get what you inspect.

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