asme b31.1 (interpretação nº 20)

7/30/2019 ASME B31.1 (Interpretação Nº 20)

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INTERPRETATIONS NO. 20

Replies to Technical Inquiries

July 1, 1991, Through December 31, 1991

It h as been agreed to publish interpretations issued by th e B3 1 Com mittee concerning B3 1.1 as partof the update service to the Co de. The interpretations h ave been assigned numb ers in chronological order.

Each interpretation applies either to the latest Edition or Addenda at the time of issuance of theinterpretation o r the Edition or Add enda stated in th e reply. Subsequent revisions to the Cod e may have

superseded the reply. These interpretations 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 n ature. In these cases, a revised reply bearing

the original interpretation number with the suffix R is presented. In the case where an interpretationis corrected by Errata, the original interpretation number with the suffix E is used.

AS ME procedures provide for reconsideration of these interpretations when o r if additional infor-

mation is available which th e inquirer believes might affect the interpretation. Fu rther, persons aggrieved

by an interpretation may appeal to the cognizant ASME committee or subcommittee. As stated in the

Statement of Policy in the Code documen ts, AS ME does not "approve," "certify," "rate," or "endorse"

any item, construction, proprietary device, or activity.

Th e interpretations will be issued twice a year up to the publication of the 1995 Edition. Interpreta-tions 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 20 through 25

will be included with the update service to the 1992 Edition.



ASME B31.1

Interpretations No. 20

Cases No. 15

Date of Issuance: October 31, 1992

This update contains Interpretations No. 20 and Cases No. 15.

Copyright0 1992THE AMERICAN SOCIETY OF MECHANICAL ENGINEERS

34 5 East 47th Street, New York, N.Y. 10017All Rights Reserved



Subject

100.1.2. Power P iping Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102.2.4. Sootblower Piping System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102.3.2. Temperature Fatigue C ycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102.4.3. Weld Joint Efficiency Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104.1.2. Thickness Allowance fo r Thre ads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104.8. Stress Du e to Sustained Loads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .115. Use of Flared. Flareless. and C ompression Type Tu be Fittings . . . . . . . . . . . . . . . . . . . . . . .122.3.2. Instrument Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122.8.2(B). Nominal Pipe Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .127.4.1 1(B). Repairs t o Base M aterials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .132. N D E p r i o r t o P W H T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Hot Tapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Scope of Application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Table 132. PW HT of P-No 5 Socket Welds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Use of Cast Iron Valves in Fuel Gas. Caustic and Acid Service . . . . . . . . . . . . . . . . . . . . . . . . . . .Valving for Feedwater Piping in Heat Recovery Steam Generators . . . . . . . . . . . . . . . . . . . . . . . .

Interpretation

20-10

20- 15

20-6

20- 11

20- 1

20- 12

20-14

20-4

20-9

20- 13

20-320-7

20- 16

20-8

20-5

20-2

File No .B31-91-036



83 .1 Interpretations No. 20

Interpretation: 20 -12

Subject: B31.1, 104.8, Stress Due to Sustained Loads

Date Issued: November 7, 1991

File: B3 1-90-003

Question: Does the B31.1, Para. 102.3.2(D) provide rules to evaluate the displacment effects of asupport element (a pinned brace, for example) that loads a piping system similar to a one-time anchorsettlement?

Reply: No, but the B31.1 does offer some guidance in the Introduction. "When no Section of theASME Code for Pressure Piping, specifically covers a piping system, at his discretion the user may select

any Section determined to be generally applicable. However, it is cautioned that supplementary require-ments to the Section chosen may be necessary to provide for a safe piping system for the intendedapplication. Technical limitations of the various Sections, legal requirements, and possible applicabilityof other codes or standards are some of the factors to be considered by the user in determining the

applicability of any Section of this Code."


Subject: B3 1.1, 127.4.1 l(B), Repairs to Base Materials


File: B3 1-91-023

Question (1): Is weld metal which is deposited on the inside diameter ofa piece of pipe or fittingsolely for the purpose of being able to machine a controlled counterbore dimension considered a repairto base material? The weld metal which is deposited does not become part of the minimum wall aftermachining.

Reply (1): No.

Question (2): If the weld metal deposited above in question (1) is to be used for both machiningof a controlled counterbore dimension and for minimum wall thickness after machining, is it to beconsidered a base metal repair.

Reply (2): Yes.



20-14, 20-15, 20-16 831.1 Interpretations No. 20

Interpretation: 20-14

Subject: B3 1.1, 115, Use of Flared, Flareless, and Compression Type Tube Fittings.


File: B3 1-91-025

Question: Is it acceptable to use flared, flareless, and compression type tubing fittings not listed in

Table 126.1 provided the requirements of Para. 115 are met?

Reply: Yes. See also Para. 123.2.1


Subject: B31.1, Paragraph 102.2.4, Sootblower Piping System


File: B3 1-91-029

Question: Are the calculated stresses in a sootblower piping system due to occasional transient

operating conditions (such as conditions during operation of a safety valve) permitted to exceed the

maximum allowable stress from Appendix A by the amounts permitted in Paras. 102.2.4(A) and (B)?

Reply: Yes; also see Para. 104.8.2


Subject: B3 1.1, Scope of Application


File: B31-91-035

Question: Does ASME B31.1 apply to piping systems within fuel cell electric generating plants?

Reply: Yes.



831.1 Interpretations No. 20


Subject: B3 1.1, 102.3.2, Temperature Fatigue Cycles

Date Issued: July 18, 1991

File: B31-91-001

Question: Does thef factor in Para. 102.3.2 apply to determining allowable stresses for a dynamic

variation (vibration) superimposed on a sustained stress not exceeding the allowable?

Reply: No. Paragraph 101.5.4 addresses this subject.


Subject: B3 1.1, Hot Tapping

Date Issued: October 2, 1991

File: B3 1-90-023

Question: What rules apply to hot tapping of piping constructed to the rules of B31. l?

Reply: The hot tapping operation is not specifically addressed by the Code. However, all require-

ments that are applicable to branch connections (design, materials, fabrication, examination, and con-

struction) and the resulting system loads also apply. If specially designed components are used, Para.

104.7.2 also applies. The conditions under which the hot tap is made (i.e., welding on material containing

fluid) shall also be considered with regard to how they affect the welding process and the resulting

material properties.

Interpretation: 2 0- 8

Subject: B31.1, Table 132, PWHT of P-No. 5 Socket Welds


File: B3 1 90-63R

Question: Does the term "maximum material thickness of Y2 in." as used in Table 132, P-No. 5,

Note (l)(a)(2) apply to the thicker of the materials being joined at the weld?

Reply: Yes.



20-9, 20-10, 20-1 1


Subject: B3 1.1, 122.8.2(B), Nominal Pipe Size

B3 1.1 Interpretations No. 20


File: B31-91-011

Question: Paragraph 122.8.2(B) states: ". . . sizes 2% in. and larger and extra strong in sizes 2 in.

and smaller." Are these sizes NPS 2% and NPS 2, respectively?

Reply: Yes.

Interpretation:20-10

Subject: B3 1.1, 100.1.2, Power Piping Systems


File: B31-91-036

Question: Within a plant property line, may B31.1 jurisdiction begin at a second plant-installed

meter downstream of the gas company's meter?

Reply: No, B31.1 jurisdiction begins at the outlet of the gas company's metering station.


Subject: B3 1.1, 102.4.3, Weld Joint Efficiency Factors


File: B31-91-037

Question: May electric resistance welded (ERW)ubular products produced under SA, ASTM, or

API specificationsbe used with a joint efficiency factor of 100% if additional requirements are met per

Table 102.4.3 of B31.11

Reply: No.





Subject: B3 1.1, 104.1.2, Thickness Allowance for Threads


File: B3 1-89-037

Question: In Para. 104.1.2(a), under subparagraph (4) of nomenclature for t,, does the phrase

"forming or machining for jointing" include threading of pipe (and other component) ends as are

commonly used to join components together?

Reply: No.


Subject: B31.1, Valving for Feedwater Piping in Heat Recovery Steam Generators


File: B3 1-89-038

Question (1): A 3-pressure heat recovery steam generator (HRSG) has three evaporators (HP, IP,

LP), each fed by a common supply which has passed through an economizer. Each evaporator has its

own feedwater regulating station. Some installations have an LP feedwater supply through the econo-

mizer and so the HP and IP evaporators each need a feedwater pump as well. Assuming the economizer

and each evaporator has its own Manufacturer's Data Report so that all interconnecting piping is BEP,

what is the required feedwater valving and where is (are) the BEP terminal(s) if there is only one HRSG

per feedwater source?

Reply (1): Each evaporator and the economizer are treated as separate boilers with respect to theirinlet feedwater valving. Each evaporator shall have an inlet stop valve, check valve, and regulating valve.

The economizer shall also have an inlet stop valve and check valve. It may also be equipped with an

outlet stop valve. In the case of multiple HRSG's, the inlet to the economizer shall have a regulating

valve, unless the regulating function is performed by the valves installed at the inlets to each evaporator.

The BEP terminals in each case are the inlet to the first valve on the economizer inlet string and the

joints where the piping interfaces with the economizer and evaporator headers.

Question (2): Assuming the economizer and each evaporator are supplied under the same Manufac-

turer's Data Report so that all interconnecting piping is boiler proper, what is the required feedwater

valving and where is (are) the BEP terminals if there is only one HRSG per feedwater source? If there

are multiple HRSG's for a common feedwater source?

Reply (2): Each evaporator shall have an inlet stop valve, check valve, and regulating valve. The

economizer shall also have an inlet stop valve and check valve. Since all inter-connecting piping is boiler

proper, there need be no discharge stop valve on the economizer. In the case of multiple HRSG's, the

inlet to the economizer shall have a regulating valve, unless the regulating function is performed by the

valves installed at the inlets to each evaporator. The BEP terminals are the inlet to the first valve in the

economizer inlet string, and the inlet piping interface with the economizer inlet header.





Subject: B3 1.1, 132, ND E prior to P W HT

Da te Issued: July 17, 1991

File: B31-91-017

Question: Does B3 1.1 require tha t NDE be performed o n welds after they have been subjected to

the postweld heat treatment required by Para. 132?

Reply: No.


Subject: B3 1.1, 122.3.2, Instru men t Con nections

Da te Issued: July 17, 1991

File: B3 1-9 1-022

Question (1): Does B31.1-1989 Edition, Para. 122.3.2(A.l) require instrument piping take-offconnections to be not less than NPS 94 for service conditions in excess of either 900 psi or 8WF?

Reply (1): Yes.

Question (2): Does Para. 122.3.2(A. 1) also apply to tappin g on t he periphery of orifice plate flanges?

Reply (2): Yes.


Subject: B3 1.1, Use of Cast Iron Valves in F uel G as, Caustic a nd Acid Service


File: B3 1-90-005

Question (1): Fo r the purpose of material selection of a plug valve tha t meets the requirem ents ofPara. 107 of B31.1, is the plug considered a pressure retaining part?

Reply (1): No.

Question (2): Does B31.1 allow the use of cast iron bodied valves and fittings, with or withoutcorrosion-resistant linings, for acid an d cau stic service?

Reply (2): Yes, unless the chemical concentration in the system fluid is so high th at it is consideredto be toxic. See Para. 122.8.2.

asme b31.1 (interpretação nº 20)

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