ASME B31.1 (Interpretação Nº 34)

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ASME B31.1

INTERPRETATIONS NO. 34

Replies to Technical Inquiries

July 1,1999, Through December 31,1999

It has been agreed to publish intepretations issued by the B31 Committee concerning B31.1 as part

of the update service to the Code. The interpretations have been asssigned numbers in chronological

order. Each interpretation applies either to the latest Edition or Addenda at the time of issuance of

the interpretation or the Edition or Addenda stated in the reply. Subsequent revisions to the Code mayhave superseded the reply.

The replies are taken verbatim from the original letters, except for a few typographical and editorial

corrections made for the purpose of improved clarity. In some instances, a review of the interpretation

revealed a need for corrections of a technical nature. In these cases, a revised reply bearing the original

interpretation number with the suffix R is presented. In the case where an interpretation is corrected

by Errata, the original interpretation number with the suffix E is used.

ASME procedures provide for reconsideration of these interpretations when or if additional information

is available which the inquirer believes might affect the interpretation. Further, persons aggrieved by

an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in theStatement of Policy in the Code documents, ASME does not "approve," "certify," "rate," or "endorse"

any item, construction, proprietary device, or activity.

Interpretations Nos. 2 through 7 were included with the update service to the 1983 Edition and

Interpretations Nos. 8 through13

were included with the update service to the 1986 Edition. InterpretationsNos. 14 through 19 were included with the update service to the 1989 Edition. Interpretations Nos.

20 through 25 were included with the update service to the 1992 Edition. Interpretations Nos. 26

through 30 were included with the update service to the 1995 Edition. For the 1998 Edition, interpretations

will be issued as necessary up to twice a year until the publication of the 2001 Edition.



Subject Interpretation

102.2.1 and 1 04.5. I(A), External Forces and Moments Acting on a Flange. . . . . . . . . 34 - 1102.3.2(D) and 102.3.3(A), Inclusion of SIF's for Longitudinal Stresses . . . . . . . . . 34-2

File No.



B31.1 Interpretations No. 34

Interpretation: 34-1

Subject: B3 1.1, Paras. 102.2.1 and 104.5.1 A), External Forces and Moments Acting on a Flange

Date Issued: July 2 1, 1999

File: B3 1-97-042

Question (1): When selecting a flange on the basis of the pressure-temperature rating given in ASME

B 16.5, i n accordance with B3 1.1, paras. 102.2.1 and 104.5. (A), is it required to consider any external

forces and moments acting on the flange?

Reply (I ): Yes. Paragraphs 102.2.1 and 104.5.1 relate to pressure design only. In addition to pressure

design, piping systems must be designed for external forces and moments (see para. 101.1).

Question (2): If a flange is designed in accordance with ASME Boiler and Pressure Vessel Code, Section

VIII, Division 1, as allowed by B3 1.1, para. 104.5.1 A), is it required that the design pressure be increased

to account for external forces and moments acting on the flange?

Reply (2): No. B3 1 . 1 does not specify a method to be used to account for external forces and moments.

The equivalent pressure method (see nonmandatory Appendix 11, para. 4.2.3) is just one acceptable methodused to account for external forces and moments.

Queston (3): Is the method of analyzing a flange, in accordance with B31.1, Appendix 11, para. 4.2.3,

to prevent leakage of the flange, or is it to prevent failure of the flange itself?

Reply (3): The equivalent pressure method is intended to prevent overloading of the flange due to the

combination of internal pressure and external moments. The failure mode due to overloading of the flange

is not specified by the Code.

Question (4): When analyzing a flange, in accordance with B31.1, Appendix 11, para. 4.2.3, can the

Committee provide a method of converting a moment about a center line of the flange into an equivalentpressure?

Reply (4): The Committee does not recommend, endorse, or approve methods of analysis, except where

stated basic design principles and formulas are supplemented as deemed necessary with specific requirements

to assure uniform application of principles and to guide selection and application of piping elements

Interpretation: 34-2

Subject: B3 . I, 1967 Edition, Paras. 102.3.2(D) and 102.3.3(A), Inclusion of SIF's for Longitudinal Stresses

Date Issued: July 2 1,1999

File: B3 1-97-056

Question: Does USAS B3l . 1-1967, paras. 102.3.2(D) and 102.3.3(A), require consideration of intensified

longitudinal stresses (load divided by the cross section based on nominal pipe properties) produced by

weight and other sustained andlor occasional loads?Reply: No. USAS B31.1-1967 does not require that the stress intensification factors (SIF's) listed in

Appendix D, or fraction thereof, be applied to the longitudinal stresses produced by weight and other

sustained/occasional loads. However, as stated in the Foreword, the Code never intentionally puts a ceilinglimit on conservatism, and a designer is free to specify more rigid requirements as he feels they may be

justified.

ASME B31.1 (Interpretação Nº 34)

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