ASME B31.1 (Interpretação Nº 25)

7/30/2019 ASME B31.1 (Interpretação Nº 25)

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INTERPRETATIONS NO. 25

Replies to Technical Inquiries

January 1, 1994, Through June 30, 1994

It has been agreed to publish interpretations issued by the B31 Committee concerning B31.1

as part of the update service to the Code. The interpretations have been assigned 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 Subsequent revisionsto the Code may have superseded the reply. These inter pretations are not a part of the Code or the

Addenda.

These 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 the Statement of Policy in the Code documents, ASME does not "approve," "certify,"

"rate," or "endorse" any item, construction, proprietary device, or activity.

The interpretations will be issued twice a year up to the publication of the 1995 Edition.

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

Interpretations Nos. 8 through 13 were included with the update service to the 1986 Edition.

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

Interpretations Nos. 20 through 25 will be included with the update service to the 1992Edition.



Subject . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .. . . .00.1.3(C), Design Pressure. . . . . . . . . . . . . .. . . . . . . . . . . . . . . .. . . . . . . . . . . . . . .. . . . . . . . . . . . . . . .01.5,DynamicEffects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .02.2.4, Variation from Normal Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .04.1.2(A.1), Minimum Wall Thickness of Pipe104.3.1.Branch Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . .04.8, Analysis of Piping C omponen ts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .07. Valves for Vacuum Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18. Sleeve Coupled an d P rop rieta ~y oints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22. Design of Specific Piping Systems. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . .22. Installation of Safety Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22.1.1(A), Pressure Design for BEP

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22.6.2(D), Pressure Relief Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22.7.3(B), Piping for Flammable Liquids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27.4.2, Circumferential Weld Surface C ontours. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27.4.2(D). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35. Pipe Assembly Tolerances. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36.4.2, Visual Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36.4.2, Visual Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37.3.2, Testing of Nonboiler External Piping. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37.3.2 and 137.7.1, Hydrostatic Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ppendix D. Welding Tee per B16.9 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ig. 127.4.4(C). Minimum Welding Dimensions. . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . . . .. . . . . . . . . . .able 132. Postweld Heat Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .able 136.4, Nondestructive Examination R equirements

Interpretation25-13

File No .B31-92-067B31-93-13

B31-92-068

B31-94-11

B31-92-071B31-93-040

B31-94-08

B31-94-10

B31-94-07

B31-93-037

B31-93-18

B31-93-11B31-92-036B31-90-035

B31-93-48

B31-94-021

B31-93-023B31-93-047

B31-93-038

B31-93-043

B31-93-14

B31-94-023

B31-94-027

B31-94-024



B31.1 Interpretations No. 25

Interpretation: 25-1

Subject: B31.1, 127.4.2, Circumferential Weld Surface Contours

Date Issued: March 15, 1994

File: B3 1-90-035

Question (1): When not specified by the designer, is it permissible to fabricate a weld which

partially fills the groove between pipe, between fittings, or between pipe and a fitting so long as the

minimum wall thickness requirement of Para. 104.1.2 is met and a transition between the weld

surface and the pipe or fitting surface is provided in accordance with Para. 127.4.2(C)?

Reply (1): No.

Question (2): When specified by the designer, is it permissible to fabricate a weld which partially

fills the groove between pipe, between fittings, or between pipe and a fitting so long as the minimum

wall thickness requirement of Para. 104.1.2 is met and a transition between the weld surface and

the pipe or fitting surface is provided in accordance with Para. 127.4.2(C)?

Reply (2): Yes.


Subject: B31.1, 102.2.4, Variation from Normal Operation


File: B3 1-92-068

Question: When considering variations from normal thermal operating cycles, can the right sideterm of Eq. (13A), Para. 104.8.3, be multiplied by the 1.15 or 1.20 values contained in Para. 102.2.4?

Reply: No. The increases in allowable stresses for pressure design permitted by Para. 102.3.2(A)

and for occasional loads permitted by Para. 102.3.3(A), are not permitted in the evaluation of cyclic

stress ranges. Paragraph 102.2.4 provides limitations for pressure stress magnitudes, whereas the

right hand side of Eq. (13) is a limitation for cyclic thermal expansion stress ranges.


Subject: B31.1, 104.3.1, Branch Connections


File: B31-92-071

Question: In accordance with Para. 104.3.1(C.l), does a tee manufactured to ANSI B16.9 meet

the pressure requirements of ASME B31.1, as far as reinforcement in the crotch is concerned?

Reply: Yes. However, further consideration may be necessary for other loadings.





Subject: B31.1, 122.6.2(D), Pressure Relief Devices


File: B31-93-11

Question: Does Para. 122.6.2(D) of ASME B31.1 require that discharge lines from pressure

relieving safety devices be designed to facilitate drainage of any expected accumulation?

Reply: Yes.

Interpretation:25-5

Subject: B31.1, 101.5, Dynamic Effects


File: B31-93-13

Question: Is it the intent of ASME B31.1, Para. 101.5, that dynamic effects of earthquake,

impact, wind, and vibration must be considered by the piping designer, even if not specified by the

owner?

Reply: Yes. Consideration may or may not involve analysis.


Subject: B31.1, 122.1.1(A), Pressure Design for BEP


File: B31-93-18

Question: This Inquiry relates to Boiler External Piping, as defined in Para. 100.1.2(A) of ASME

B31.1, for steam service. The set pressure of the boiler safety valve is less than the maximum

allowable working pressure of the boiler. Is it permissible to use the set pressure of the boiler safety

valve as the internal design pressure for the steam piping?

Reply: Yes, provided that all applicable requirements of Paras. 122.1.1(A) and 122.1.2 of ASME

B31.1 are met and the internal design pressure for the steam piping is not less than 100 psig.





Subject: B31.1, 136.4.2, Visual Inspection


File: B31-93-023

Question (1): May the required visual examination of the completed weld occur after the

pressure test required by Para. 137?

Reply (1): The ASME B31.1 Code does not specify when the required examination of the

completed welds should be performed.

Question (2): Is it a requirement of the ASME B31.1 Code that the fabrication sequence shall

be arranged so as to provide for making the maximum number of joint inside surfaces "readily

accessible" for examination for incomplete penetration?

Reply (2): No.

Question (3): Paragraph 136.4.2 of the ASME B31.1 Code references "portions of a compo-

nent." What is the definition of a component?

Reply (3): Component is defined in Para. 100.2.

Question (4): Is it required that the required visual examination occur "before, during, or after

the manufacture, fabrication, assembly, or test" as stated in the ASME B31.1 Code, Para. 136.4.2?

Reply (4): No. Visual examinations may occur whenever the examiner wishes to be present.

However, it is required that the completed weld receive a visual examination that verifies that the

completed weld meets the acceptance criteria of Para. 136.4.2.

Question (5): What inspections are required by the ASME B31.1 Code?

Reply (5 ) : The inspections required are those that the Owner's inspector (as defined in Para.

136.1) or the Authorized Inspector (as required when the system is Boiler External Piping) has

determined to be needed in order to assure the piping has been constructed in accordance with the

applicable requirements of the ASME B31.1 Code.


Subject: B31.1, 122, Installation of Safety Valves


File: B31-93-037

Question: Does ASME B31.1 require that valves, addressed within the scope of Para. 122, be

installed with the valve stem either at or above the horizontal plane to prevent entrapment of liquids

within the valve bonnet?

Reply: No. The inquirer is referred to Para. 107.1(C).



25-9,25-10,25-11

Interpretat ion: 25-9

Subjec t: B31.1, Pa ra. 137.3.2, Testing of Non boiler External Piping

Da te Issued: March 15, 1994


File: B31-93-038

Question (1): For piping used with a h ot water bo iler designed for 150 psig a nd 210°F, are thetest requ iremen ts of P ara. 137.3.2 applicable?

Reply (1): Yes.

Question (2): For the above referenced piping, are full penetration welds required?

Reply (2): Yes, except for welds designed in accordance w ith P ara. 104.3.1(C.2) and fabricatedin accordance with Para. 127.4.8(F).

Interpretat ion: 25-10

Subjec t: B31.1, 136.4.2, Visual Inspection


File: B31-93-047

Question: Do es ASM E B31.1 set an accep table limit for acceptance of surface porosity foundby visual examination?

Reply: No.

Interpretat ion: 25-1 1

Subjec t: B31.1-1967, 127.4.2 (D)


File: B31-93-48

Question: Does the reinforcement requirements detailed in USAS B31.1-1967 Edition, Para.127.4.2(D), apply to the root reinforcement of single V butt weld p ipe joints?

Reply: No.





Subject: B31.1, 137.3.2 and 137.7.1, Hydrostatic Test

Date Issued: April 22, 1994

File: B31-93-043

Question (1): Does ASME B31.1 define the term "not practical" in Para. 137.7.1?

Reply (1): No. It is the responsibility of the owner to determine which test shall be done on

NBEP. See Para. 137.3.2

Question (2): Does ASME B31.1 exempt piping, valves, and fittings NPS 1 inch and less from

hydrostatic test requirements?

Reply (2): No.


Subject: B31.1, 100.1.3(C), Design Pressure

Date Issued: April 29, 1994

File: B31-92-067

Question: What rules of ASME B31.1 apply to the design pressure of piping downstream of a

pressure reducing valve?

Reply: The design pressure of piping downstream of a pressure reducing valve shall be deter-

mined in accordance with the rules of Para. 101.2.2. Where the design pressure is less than that ofthe piping upstream of the pressure reducing valve, the requirements of Para. 122.5 shall be met.


Subject: B31.1, 122.7.3(B), Piping for Flammable Liquids

Date Issued: June 22, 1994

File: B31-92-036

Question (1): For flammable and combustible liquids, does ASME B31.1, Para. 122.7.3(B),

permit the use of copper tubing, where metal temperatures do not exceed 400°F, to match thecopper alloy fittings permitted in this paragraph?

Reply (1): No. The allowance applies only to copper alloy valves and fittings.

Question (2): Does Para. 122.7.3(C) permit copper tube and copper alloy valves and fittings in

areas having metal temperatures between 400°F and 500°F?

Reply (2): No.





Subject: B31.1, Appendix D, Welding Tee per B16.9


File: B31-93-14

Question (1): May the applicable flexibility and stress intensification factors in B31.1, Appendix

D, be used for a welding tee manufactured in accordance with ASMEIANSI B16.9 without supple-

mentary dimensional specifications?

Reply (1): Yes.

Question (2): Is the manufacturer of a welding tee specified for use in B31.1 piping system and

manufactured in accordance to ASMEIANSI B16.9 without supplementary dimensional specifica-

tions obliged to comply with any requirements of ASME B31.1, Appendix D?

Reply (2): No.


Subject: B31.1, 104.8, Analysis of Piping Components

Date Issued: June 22. 1994

File: B3 1-93-040

Question: Referring to Para. 104.8.4, Eqs. (ll), (12), and (13), how should the moment values

for sustained and occasional loads, MA and M,, and the moment-range value for thermal expansion

Mc be determined considering the effect that varying gaps may exist between the pipe and itssupports at different times during operation?

Reply: The Code does not specify how to calculate moments and moment-ranges due to dif-

ferent loads or combinations of loads. In the determination of loads, gaps produce nonlinearities in

the analyses which may often be considered negligible.


Subject: B31.1-1992, 122, Design of Specific Piping Systems


File: B31-94-07

Question: Does Para. 122 of ASME B31.1 Code require that eccentric reducers with flat side

up be provided upstream of pressure control valves when the valves are sized smaller than the

pipeline?

Reply: No.



B31.1 Interpretations No . 25


Subject: B31.1-1992, 107, Valves for Vacuum Service


File: B31-94-08

Question: Does ASME B31.1 require that valves used in vacuum service have an external sealing

arrangement, such as seal water to gland packing, to prevent air from entering the system.

Reply: No.


Subject: B31.1-1992, 118, Sleeve Coupled and Proprietary Joints


File: B31-94-10

Question: Does Para. 118 of ASME B31.1 Code require tie-rods (control units) to meet the

requirement for "adequate provision to prevent separation of the joint"?

Reply: No.


Subject: B31.1-1989, 104.1.2(A. ), Minimum Wall Thickness of Pipe


File: B31-94-11

Question (1): May a measured minimum wall thickness of pipe be used to verify B31.1 Power

Piping Code compliance with the design minimum wall thickness?

Reply (1): Yes.

Question (2): What Code or Standard must be used to measure the pipe wall thickness?

Reply (2): The Code does not specify how to measure the pipe wall thickness?





Subject: B31.1, 135, Pipe Assembly Tolerances


File: B3 1-94-021

Question: Does piping fabricated to the fabrication tolerances of PFI Standard ES-5 (Fabri-

cating Tolerances) meet the requirements of ASME B31.1?

Reply: ASME B31.1 does not specify the fabricating tolerances. This is a responsibility of the

designer.


Subject: B31.1, Fig. 127.4.4(C), Minimum Welding Dimensions


File: B31-94-023

Question: In Fig. 127.4.4(C), is a maximum weld size specified?

Reply: No. However, the weld size may be limited by the physical configuration of the joint.


Subject: B31.1, Table 136.4, Nondestructive Examination Requirements


File: B31-94-024

Question: In Table 136.4, for buttwelds on piping over NPS 2, is radiography required for all

pressures, regardless of the design temperature?

Reply: No.





Subject: B31.1, Table 132, Postweld H eat Tre atme nt


File: B3 1-94-027

Question: I s th e "nominal thickness in accordance with Para. 132.4.1" the sam e as the "nominalmaterial thickness," m entioned in Notes (I)(B) for P-Nos. 1 and 3 in Table 132?

Reply: No. Th e "nominal thickness in accordance with Par a. 132.4.1" may be th e weld thickness

under some specified conditions but the "nominal material thickness" is always the material thick-

ness.

ASME B31.1 (Interpretação Nº 25)

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