ASME B31.1 INTERPRETATIONS VOLUME 45

ASME B31.1 INTERPRETATIONS VOLUME 45

B31.1

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ASME B31.1 INTERPRETATIONS VOLUME 45

Interpretation: 45-1

Subject: B31.1-2007, Para 101.7.2, Expansion Joints

Date Issued: January 27, 2009

File: 07-1440

Question: Since para. 101.7.2 excludes bellows, slip, or sleeve type expansion joints from use in any piping system connecting the boiler and the first stop valve, are other types of expansion joints excluded?

Reply: No.

Interpretation: 45-2

Subject: B31.1-2004, Definition of Sustained Pressure, Minimum Wall Thickness Calculation

Date Issued: February 6, 2009

File: 06-1432

Question (1): Is Òmaximum sustained pressureÓ referenced in para. 122.13 referring to the Òmaximum sustained operating pressureÓ exerted by the pump as described in para. 101.2.2?

Reply (1): Yes.

Question (2): When determining the value of P to be used in the minimum wall thickness equations of para. 104.1.2, is it acceptable for the designer to take into account automated protection devices, such as safety/relief valves, to reduce the piping design pressure?

Reply (2): Yes.

Interpretation: 45-3

Subject: B31.1-2007, Para. 122.3.2(B), Instrument Piping Valves

Date Issued: April 13, 2009

File: 08-672

Question: Is it the requirement of para. 122.3.2(B.2.2) of the 2007 Edition of ASME B31.1, when blowdown valves are used, that the rating of the valves at the instrument be equal to 1.5 times the design pressure of the piping system at 100¡F and need not exceed the rating of the blowdown valves?

Reply: Yes.

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ASME B31.1 INTERPRETATIONS VOLUME 45

Interpretation: 45-4

Subject: Para. 104.8.1, Pipe Nominal Wall Thickness

Date Issued: May 26, 2009

File: 08-1793

Question: Should the pipe nominal wall thickness without deduction for mechanical, corrosion, and erosion allowance be used for the calculation of the section modulus to determine the longitudinal stress due to weight and other sustained mechanical loads in para. 104.8.1, eq. (11)?

Reply: Yes.

Interpretation: 45-5

Subject: Table 136.4

Date Issued: July 1, 2009

File: 08-1755

Question (1): When the requirements of General Note (a) of Table 136.4 have been met, is 100% RT or UT required for all butt welds greater than NPS 2 with design temperatures over 750¡F?

Reply (1): Yes.

Question (2): When the requirements of General Note (a) of Table 136.4 have been met, is 100% RT or UT required for all butt welds greater than NPS 2 and thickness over 3Ú4 in. with design temperatures between 350¡F and 750¡F and pressures in excess of 1,025 psig?

Reply (2): Yes.

Interpretation: 45-6

Subject: B31.1-2004 Edition, Para. 131.6

Date Issued: September 17, 2009

File: 09-818

Question (1): Piping of material belonging to P-No. 3, 4, 5A, 5B, or 6 is tack welded using a qualified WPS. The tack welds are made using bridge tacks that will be slow cooled, removed, and the area examined for cracks prior to welding the joint. Per B31.1-2004 Edition, para. 131.6.1, does this tack weld constitute the commencement of welding that would then require the preheat to be maintained until the requirements of para. 131.6.1(A) or para. 131.6.1(C) are met?

Reply (1): No.

Question (2): Welding has been completed on piping of material belonging to P-No. 5B and has been allowed to cool to 200¡F or lower to achieve a fully martensitic microstructure just prior to performing the required PWHT. Per B31.1-2004 Edition, para. 131.6.1, does the weld described in the background constitute an interruption of welding?

Reply (2): No.

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ASME B31.1 INTERPRETATIONS VOLUME 45

Interpretation: 45-7

Subject: Table 121.5, General Note (c)

Date Issued: November 30, 2009

File: 09-971

Question: Is the suggested pipe support spacing table based on stress not exceeding 2,300 psi (15.86 MPa) with a sag of no greater than 0.1 in. (2.5 mm) between supports?

Reply: Yes.

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