ASME/ANSI Interpretations No. 7. Replies to Technical Inquiries May 1, 1988, Through April 30, 1989

Transcription

1 ASME/ANSI Interpretations No. 7 Replies to Technical Inquiries May 1, 1988, Through April 30, 1989 Gener~1 Inform~tion It has been agreed to publish interpretations issued by the 831 Committee concerning as partofthe subscription service. The interpretations have been assigned numbers in chronological order. An interpretation applies to the Edition or Addenda stated in the interpretation or, if none is stated, to the Edition or Addenda in effect on the date of issuance of the interpretation. Subsequent revisions to the Code may have superseded the reply. The interpret~tions ~re not part of the Code or its Addend~. 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 na,ture. In these cases, a revised reply, bearing the original intrepretation number with the 'suffix R, is presented. 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. For detailed instructions on preparation of technical inquiries to the 831 Committee, refer to Appendix Z. Code Reference ~nd Subject Indexes Code Reference and Subject Indexes have been prepared to assist the user in locating interpretations by location or by subject matter in the Code. They cover interpretations issued from Volume 1 up to and including the present volume, and will be updated with each volume.,,,":"/, 1.< ::.: 69

2 831.3 Subject Interpretation File No. Paras. 300, 300.1, and Fig ; Applicability,. Paras. 300(c)(3) and (5), and ; Longitudinal Stresses and Longitudinal 8ending Stresses-Sustained Loads. Paras.'3OO(c)(3l, , , and 319.7; Piping Supports. Paras , , and ; Pressure Relief Device Set Pressure. Paras , , and ; Allowable Stress-Calculating Displacement Stress Range. Paras and 328; Spacing of Welds.. '.' Para , and Tables A 1 and A 1 B; Spiral Welded Pipe. Para (f) and Fig ; 8ranch Reinforcement. Para. A ; Qualification Test for CPVC Piping. Paras. K315 and K322.3; Tubing Joints-Instrument Piping. Table A; Weld Acceptance Criteria-Concavity and Convexity R " B31-88-OO B

3 831.3 Interpretations No R,7-01 Interpret~tion: 6-03R Item: ANSI/ASME B Edition, Paras. 300(c)(3) and (5), and ; Longitudinal Stresses and Longitudinal Bending Stresses-Sustained Loads B Question (1): In accordance with ANSI/ASME B31.3, para (c), when calculating the longitudinal stresses due to pressure, weight and other sustained loads, should the thickness of pipe used in calculating SL be the nominal thickness minus mechanical, corrosion, and erosion allowances but not minus the manufacturer's mill tolerance? Reply (1): Yes. Question (2): In accordance with ANSI/ASME B31.3, para (C) when calculating the longitudinal bending stresses due to sustained loads, what stress intensification factors should be applied? Reply (2): ANSI/ASME B31.3 does not address the application of stress intensification factors for longitudinal stress due to sustained loads; but see ANSI/ASME B31.3, paras. 300(c)(3) and (5). Interpret~tion: 7-01 r. \ ~~t;. ANSI/ASME Edition with Addenda through 831.3c-1986, Paras , , and ; Pressure Relief ~vice Set Pressure May 24,1988 B Question: In accordance with ANSI/ASME 831.3, paras and , may the set pressure of a single pressure relieving device for a piping system be chosen higher than the design pressure of the piping system provided para is satisfied for the maximum relieving pressure? Reply: No. 73

4 7-02, Interpretations No. 7 Interpretation: 7-02 ASME/ANSI B Edition, Paras and 328; Spacing of Welds B I Question: In accordance with ASME/ANSI B31.3, are there requirements or guidelines on the minimum distance between welds in a pipe? Reply: No, except as provided in para (e). Interpretation: 7-03 ASME/ANSI B Edition, Para , and Tables A-1 and A-1 B; Spiral Welded Pipe B Question (1): In accordance with ASME/ANSI B31.3, Table A-1, does ASTM A 671 and A 672 as listed, apply for both straight welded pipes and spiral welded pipes? Reply (1): No. ASTM A 671 and A 672 do not include spiral welded pipe. ASTM specifications covering spiral welded pipe include "spiral welding" in their scope. These include ASTM A 134, A 139 and A 211. API-5L also includes spiral welding. See ASME/ANSI B31.3, Table A-1 B. Question (2): In accordance with ASME/ANSI B31.3, para , can carbon steel spiral welded pipe be used for severe cyclic service? Reply (2): No. 74

5 831.3 Interpretations No Interpretation: 7-04 ASME/ANSI Edition, Paras , , and ; Allowable Stress-Calculating Displacement Stress Range Question (1): In accordance with ASME/ANSI 831.3, para , should the basic allowable stress at maximum metal temperature Sh used for calculating the allowable displacement stress range, be for the normal upper temperature underoperatif1g conditions, and exclude all short-time excursions above such normal operating temperature? Reply (1): No. In accordance with para , the allowable displacement stress range is based on the maximum and minimum temperatures for the displacement cycle under analysis.. Question (2): Are the provisions of ASME/ANSI 831.3, para applicable for establishing the allowable displacemeot stress range for flexibility analysis? Reply (2): No. i ""'.:. \ "',.,_.,...,'- -~.' 7S

6 1-05, Interpretations No. 1 Interpretation: 7-oS ANSI/ASME B Edition with Addenda through B31.3c-1986, Paras. 300(c)(J), , and 319.7; Piping Supports 6 ~~< '.. :~-.. B Question (1): When a pipe moves away from a support, should the longitudinal stresses for the pipe in the installed po~ition, or the longitudinal stresses for the pipe in the operating position, or both, be compared to ANSI/ASME B31.3 allowable in accordance with para (c>? Reply (1): Both. See also para. 300(c)(3). Question (2): Does ANSI/ASME B31.3 require the evaluation ofthe secondary effects ofpressure, such as pressure expansion and elongation or the Bourdon effect with bends? Reply (2): No. See also para. 300(c)(3). Question (3): Does ANSI/ASM E B31.3 address the stresses caused by axial forces in the displacement stress calculations? Reply (3): No. See also paras. 300(c)(3) and Question (4): What is the ANSI/ASME B31.3 definition of "displacement stress range"? Reply (4): The displacement stress range is defined in para as tithe algebraic difference between the extreme displacement condition and the original (as installed) condition (or any anticipated condition with a greater differential effect)." Interpretation: 7-06 ANSI/ASME B Edition with the B31.3a-1984 Addenda, Table A; Weld Acceptance Criteria-Concavity and Convexity. B Question: Is it the intent of ANSI/ASME B31.3 to interpret concavity and convexity by radiography on welds required by B31.3 or the engineering design to be radiographed when this interpretation can not be made by visual examination? Reply: For concavity, yes. ANSI/ASME B31.3 does not address convexity except as "internal protrusion" or "external reinforcement," neither of which is evaluated by radiography. 16 lor ~

7 831.3 Interpretations No , 7-88, 7-09 Interpretation: 7-07 ASME/ANSI B Edition, Paras. K315 and K322.3; Tubing Joints-Instrument Piping B Question: Does ASME/ANSI B31.3, para. K31 5 apply to process control (instrument piping) tube fittings and tube jo!nts? Reply: Yes. Interpretation: 7-oS ASME/ANSI B Edition, Para (f) and Fig ; Branch Reinforcement B Question: In accordance with ASME/ANSI B31.3, para (f), is the attachment weld between the reinforcement member and the run pipe required for a full encirclement type reinforcement installation? Reply: ASME/ANSI B31.3 does not specifically address full encirclement branch reinforcement. The Committee will be studying this item for possible future revisions. Interpretation: 7-09 Item: ANSI/ASME B Edition, Para. A ; Qualification Test for CPVC Piping December 8, 1988 B31-88-o21 Question: For CPVC plastic piping, is there a discrepancy between the hydrostatic test requirements in para. A for qualifying a bonding procedure specification (BPS) and the hydrostatic burst strength requirement for solvent cemented joints in ASTM F 493? Reply: No. ANSI/ASME B31.3, para. A requires that a test assembly containing joints withstand a hydrostatic test pressure of fo,:,r times the design pressure. ASTM F 493 qualifies the cement used in the joint. ',',. ~ \{~:~i; 77

8 Interpretations NO.7 Interpretation: 7-10 ASME/ANSI B Edition, Paras. 300, 300.1, and Fig ; Applicability ft'.'... t»;', o!to1 ;.' Item: December 8, 1988 B Question: Which section of the ASME/ANSI B31 Code for Pressure Piping covers piping for a transmission line between an oil terminal and a tank farm part of the piping being accessible to the public? Reply: ASME/ ANSI B31.3 and 831.4; see Fig of B31.3. L:. < 78