Interpretations No. 1 to ANSI/ASME 831.8

Transcription

1 Interpretations No. 1 to ANSI/ASME (This supplement Is not part of ANSIIASME or the Addenda It is included for Information only.) It has been agreed to publish lnterpretations issued by the 831 Committee concerning as part of the subscription service. This supplement includes lnterpretations concerning issued between January 1,1983, and December 31,1983. They have been assigned Interpretation numbers in chronological order. Each Interpretation applies to the latest Edition or Addenda at the time of issuance of the Interpretation. Subsequent revisions to the Code may have superseded the reply. Future versions of this supplement will cover inquiries issued over 1 year periods. These replies are taken verbatim from the original letters, except for a few typographical and editorial corrections made for the purpose of improved clarity. ASME procedures provide for reconsideration of these lnterpretations when or if additional information is available which the inquirer believes might affect the Interpretation. Further, persons aggrieved by an lnterpretation 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.

2 831.8 Interpretations No. 1 Interpretation: 1-1 Date Issued: March 2, 1983 Subject: Design Based on Inside Diameter File: 1622 Question: Does ANSIIASME recognize and allow design based on inside diameter? Reply: No. Interpretation: 1-2 Date Issued: March 2, 1983 Subject: Pipe-Type Holders in 844 File: 1630 Question: According to of ANSIIASME 831.8, pipe-type holders should have a minimum clearance from fenced boundaries of site of 25 ft if maximum operating pressure is less than 1000 psig, and 100 ft if pressure is 1000 psig or more. However, of ANSIIASME also allows pipe-type holders to be installed in streets, highways, or in private rights-of-way not under the exclusive control and use of the operating company if the holders are designed, installed, and tested in accordance with the provisions of the Code applicable to a pipeline in the same location and operated at the same maximum pressure. Is it contrary to the requirements of ANSllASME if a pipe-type holder, which is to be installed on site under the exclusive control and use of the operating company, does not have any clearance limitations from the fenced boundaries, but it is designed, installed, and tested in accordance with the provisions of the Code applicable to a pipeline installed in the same location and operated at the same maximum pressure? Reply: It is not intended that the additional requirements for clearance from fenced boundaries set out in (a) and (b) be applied to pipe-type bottle holders meeting the requirements for the class location in which it is installed. Interpretation: 1-3 Date Issued: April 19, 1983 Subject: Design Safety Factors File: 1612 Question: If underthickness is not allowed in pipe fabrication specification, may a safety factor greater than 0.72 be used in ANSIIASME and ANSIIASME construction? Reply: There is no provision in ANSIIASME or ANSIIASME to permit a design factor greater than 0.72 to be used in the design of a liquid petroleum pipeline or natural gas pipeline. 3

3 831.8 Interpretations No. 1 Interpretation: 1-4 Date Issued: October 26,1983 Subject: Area of Reinforcement for Contoured Integrally Reinforced Fittings File: 1681 Question: Do the rules for extruded outlets apply to contoured integrally reinforced fittings? If not, what are the correct equations indicated in ANSIIASME 831.I, B31.2,B31.3,B31.4, and to be used in determining the limits of area reinforcement for contoured integral!^ reinforced branch connecting fittings (e.g., weldolet) and extruded outlets? Reply: The contoured integrally reinforced fitting is not an extruded outlet. The equations set forth in the 831 Codes for determining the reinforcing limits of an extruded outlet do not apply in determining the reinforcing limits of a contoured integrally reinforced fitting. The equations set forth in the Code documents for fabricated intersection area reinforcement limits are the only equations available for contoured integrally reinforced branch connecting fittings.

4 lnterpretations No. 2 to ANSIIASME B31.8 (This supplement is not part of ANSiIASME or the Addenda. it is included for information only.) It has been agreed to publish lnterpretations issued by the 831 Committee concerning as part of the subscription service. This supplement includes lnterpretations concerning issued between January 1, 1984, and December 31, They have been assigned lnterpretation numbers in chronological order. Each Interpretation applies to the latest Edition or Addenda at the time of issuance of the Interpretation. Subsequent revisions to the Code may have superseded the reply. Future versions of this supplement will cover inquiries issued over 1 year periods. These replies are taken verbatim from the original letters, except for a few typographical and editorial corrections made for the purpose of improved clarity. ASME procedures provide for rensideration 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.

5 B3 1.8 Interpretations No. 2 Interpretation: 2-1 Date Issued: November 16,1984 Subject: Hoop Stresses in File: Question: To determine whether hoop stresses exceed 30% of the SMYS of pipe in of ANSI/ ASME 831.8, shall the 0.30 factor be applied to the entire hoop stress formula given in (a)? Reply: No. The 0.30 factor shall be applied to 2StlD. Factors F, E, and T are not to be used in this Case.

6 lnterpretations NO. 3 to ANSllASME (Thh rupplement is not pert of ANSllASME or the Addenda. It is included for information only.) It has been agreed to publish lnterpretations issued by the 831 Committee concerning as part of the subscription service. This supplement includes lnterpretations concerning B31.8 issued between January 1, 1985, and June 30, They have been assigned Interpretation numbers in chronological order. Each lnterpretation applies to the latest Edition or Addenda at the time of issuance of the Interpretation. Subsequent revisions to the Code may have suspended the reply. Future versions of this supplement will cover inquiries issued over 1 year periods. These replies are taken verbatim from the original letters, except for a few typographical and editorial corrections made for the purpose of improved clarity. ASME procedures provide for reconsideration of these lnterpretations when or if additional information is available which the inquirer believes might affect the Interpretation. Further, persons aggrieved by an lnterpretation 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.

7 831.8 Interpretations No. 3 Interpretation: 3-1 Subject: , Overpressure Protection for Fuel Gas Piping Date Issued: March 4, 1985 Fi le: B Question: At a power plant, high pressure natural gas is delivered to a meter set assembly which includes two regulating valves in series that reduce the natural gas pressure to a level suitable for firing the boiler. Do these two regulating valves in series provide the overpressure protection required by the ANSIIASME B31.T Code? Reply: As stated in Para (c), the scope of the ANSIIASME Code includes only the piping downstream from the meter set assembly. The meter set assembly and the piping upstream are included in the scope of the ANSVASME Code. Paragraph of the Code describes three suitable methods which may be used to regulate and limit the maximum safe value of the pressure delivered to the customer. The regulating valves, as described in this Inquiry, should be acceptable if they conform to one of the methods described in Para Interpretation: 3-2 Subject: and 825.3, Thickness to be Used to Determine Stress Relieving Date Issued: April 15, 1985 File: Question (1): A section of pipe having a wall thickness of less than 1: in. is to be welded to a fabricated tee having a nominal wall thickness greater than 1: in. which has been tapered to match the wall thickness of the pipe. Is stress relieving required per and of ANSIIASME Reply (1 1: Assuming the tee is manufactured under the appropriate MSS specification, the taper in the wall thickness of the tee is made in accordance with Appendix I of B31.8 and appropriate qualified welding procedures are employed, stress relieving is not required. Question (2): At what specific location is the wall thickness to be measured when determining the need for stress relieving as required in and of ANSIIASME B31.8? Reply (2): The determining wall thickness is the maximum wall thickness of the pipe or fitting in the heat-affected zone of the weld joint.

8 831.8 Interpretations No. 3 Interpretation: 3-3 Subject: (b) and Appendix I, Fig. 15, Acceptable End Preparations Date Issued April 1 5, 1985 File: Question: Does the joining of two equal strength pieces of pipe with unequal wall thickness, with the thicker piece being counterbored, meet the requirements of Fig. 15 of ANSIIASME B31.8? Reply: The weld configuration is one of unequal wall thickness and equal strength as depicted in Fig. 15(b), with asterisk footnote, or with equal walls as in Fig. 14. Interpretation: 34 Subject: , Installation of Gas Line Under Buildings Date Issued: June 5, 1985 File: Question: Gas piping is installed beneath a building floor. Does (b) require that the portion of the piping under the building, but not necessarily the section outside the building, be encased in a gas tight conduit? Reply: Yes.

9 I nterpretations No. It has been agreed to publish interpretations issued by the 831 Committee concerning as part of the update service. This supplement includes interpretations concerning issued between January 1, 1986, and December 31, They have been assigned interpretation numbers in chronological orde;. Each interpretation applies 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 may have superseded the reply. The interpretations are not 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. 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 sukommittee. 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.

10 831.8 Interpretations No. 4 Interpretation: 4-1 Subject: Flexibility Factor and Stress Intensification Factor Tables Date Issued: October 17, 1986 File: Question (1 ): What is the difference between a "welding tee per ANSl " and an "extruded welding tee" as stated in Appendix D, Table D-1, of ANSIIASME and Appendix E, Table E-1, of ANSIJASME 831.8? Reply (1): A "welding tee per ANSl 816.9" complies with all requirements of ANSl An "extruded welding tee" complies with the requirements of of ANSIIASME or and of ANSIIASME Question (2): Is the difference related to ANSl dimensions as defined by ANSIJASME and ANSIIASME ? Reply (2): No. Question (3): Is the difference related to manufacturing? Reply (3): ANSI does not specify manufacturing methods. Question (4): When a "welding tee per ANSl " does not meet the radius and thickness limits specified in Appendix D, Table D-1, of ANSIJASME or Appendix E, Table E-1, of ANSIIASME 831.8, is it permissible to use the flexibility characteristic h for an "extruded welding tee" provided r, 2 Db and T, < 1.ST? Reply (4): Yes, provided the tee is formed by an extrusion process; otherwise it is the responsibility of the designer to determine the proper flexibility characteristic.

11 831. I Interpretations No. 4 Interpretation: 4-2 Subject: 826.2, NDE of Gas Compression Equipment Date Issued: December 1, 1986 File: B Question (1): According to 8?6.2, what percentage of the butt welds in new packaged gas equipment shall be examined for use in Class 3 locations? Reply (1): 100 /o if practical, but no less than 90% [see 826.2(b)(5)]. Question (2): If a gas compression package is designed and tested for use in a Class 3 location and is later relocated to a compressor station, what additional requirements apply? Reply (2): None. Question (3): A new section of piping is added to existing gys compression equipment. What percentage of the new welding is required to be examined? I I Reply (3): See Reply (11. Question (4): If new piping is added to existing gas compression equipment, is it required that any of the existing welding be examined? Reply (4): No, if it met the conditions of 826.2(b)(5).

12 Interpretations No. Replies to Technical Inquiries February 1, 1987, Through December 31, 1988 It has been agreed to publish interpretations issued by the 831 Committee concerning as part of the update sewice to the Code. The interpretations have been assigned interpretation numbers in chronological order. Each interpretation applies 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 may have superseded the reply. The interpretations are not part of the Code or the Addcmk. These replies are taken verbatim from the original letters, except for a few typographical and editorial corrections made for the purpose of improved clarity. 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.

13 831.8 Interpretations No. 5 Interpretation: 5-1 Subject: ANSIIASME 831.8, I, Overpressure of Corroded Piping Systems Date Issued: February 5, 1987 File: Question: When a reduced Maximum Allowable Operating Pressure (MAOP) of a corroded piping system has been set equal to the safe maximum pressure determined in accordance with the methods of Appendix L, may the provisions of of ANSIIASME be applied, where the piping system pressure relief or pressure limiting station(s) prevent the pressure from exceeding the reduced MAOP plus 1 P/o, or prevent the pressure from producing a nominal hoop stress greater than 7S0/b of the specified minimum yield strength, whichever is lower? Reply: The provisions of of ANSIIASME B31.8 may be applied because Appendix L provides a P' which may be less than the original design pressure or established MAOP. The P' would then become the new MAOP for purposes of determining the not-to-exceed pressure in This not-to-exceed pressure is the lower of 1 100/0 of P' or the pressure which produces a hoop stress of 75% of SMYS based on the original nominal wall thickness.

14 5-2, Interpretations No. 5 Interptation: 5-2 Subject: ANSIIASME 831.8, 841.I 23 and (c), Pipeline Reclassification Date Issued: February 5, 1987 File: Question (1): Why do the requirements in 841.I23 of ANSIIASME call for all pipeline bridges in Class 1 areas to be of Type 8 construction? Reply (1): See (a).of ANSIIASME Question (2): Where changes in population index imply that road or river crossings would require to be classified with a higher construction type, would it be necessary to reduce the maximum permissible operating pressure or replace crossings with increased wall thickness, or would it be sufficient to retest the section hydrostatically to prove the integrity? Reply (2): Class locations and population density indexes are defined in Subparagraph (c) indicates what items to study when the population density index increases. Paragraph fully covers the alternatives available with respect to retesting, lowering the MAOP, or replacing pipe as a result of a population density index increase. Question (3): In (c) the Code lists five areas to be considered in a study to reclassify a line. Is the Committee able to advise on more specific points or particular areas that should be reviewed or inspected, and the most critical points that require careful consideration when embarking on a reclassification study? Reply (3): As a Code writing body, the Section Committee is limited to interpreting the Code and cannot give advice on specific applications. Interpretation: 5-3 Subject: ANSIIASME 831.8, (dl and (c), Valves at Offshore Platforms Date Issued: February 12, 1988 Question (1): Do the requirements of ANSIIASME specify a location for valves that are required to shut off the flow of gas to an offshore platform in an emergency? Reply (11: No, only that valves or other components shall be provided to shut off the flow of gas to the offshore platform. See (d). Question (2): Do the requirements of ANSIIASME specify a location for blowdown valves? Reply (2): No, only that each section of pipeline between block valves can be blown down, and blowdown piping shall be sized such that under emergency conditions the section of line can be blown down as rapidly as is practical. See (c).

15 031.8 lnteqmtations No. 5 Subject: ANSIIASME 831.8, (a), Steel Pipe Design Formula File: Date Issued: February 12, 1988 Question: When determining design pressure for okler pipelines in place and where pipe records are minimal, wouldn't the 24,000 psi valve be a sufficient downgrade for both the E and S factors found in design formula (a) of ANSIIASME Reply: No. See Subject: ANSIIASME 831.8, 833.4, Stress Calculations File: Date Issued: April 14, 1988 Question (1 1: Paragraph of ANSIIASME states that "The sum of 833.4(b) and (c) shall not exceed 75% of the allowable stress in the hot condition...." An interpretation of this requirement is that (b) + (c) shall not exceed 54% of SMYS (75% of 72% for design factor = 0.72 locations). Does this reflect the intent of this section? Reply (1): No. The sum of (b)+(c) cannot exceed 75% of SMYS. The longitudinal pressure stress (b) is limited by , SFT. Question (2): Subparagraph (c) of ANSIIASME includes "wind" as an occasional load component. Stresses resulting from wind induced vortex shedding on above ground pipelines has always been considered a fatigue load. This fatigue load is evaluated using fatigue load criteria, and not as an occasional wind load to be included under the requirements of 833.4(c). Is this correct? Reply (2): Yes.

16 831.8 Interpretations No. 5 Interpretation: 5-6 Subject: ANSIIASME 031.8, 833, Stress Calculations File: Date Issued: April 19, 1988 Question (1): In evaluating expansion stress under ANSIIASME 831.8, should both the thermal and pressure effects be considered? If not, which of the two and why? Reply (1): Yes, but not together. Thermal effects should be considered in while pressure effects should be considered in 833.4(b). Question (2): Is axial force in a pipeline a component of the longitudinal pressure stress? Reply (2): No. The longitudinal force resulting from pressure stress is one component of axial force in a pipeline. Question (3): In of ANSIIASME 031.8, is it correct to assume that the intent is that the longitudinal pressure stress considers only the effects of pressure and that the longitudinal bending stress considers external loads, both sustained and occasional? If not, what is the intent? Reply (3): Yes. Bending stresses due to internal pressure should be considered in the longitudinal pressure stress [833.4(b)] and the external loads, sustained or occasional, should be considered in the longitudinal bending stress [833.4(c)], which are primary and not secondary.

17 831.8 Interpretations No. 5 Interpretation: 5-7 Subject: ANSIIASME 031.8, 833.4, Stress Due to Displacement File: B Date Issued: August 1 1, 1988 Question (1 1: A piping system is being designed from one offshore platform to another offshore platform via a connecting bridge as per ANSIIASME (classification of steel pipe construction Type C). Platforms are subject to severe deflections under extreme environmental conditions and their differential deflection is severe. Is this deflection effect on piping a part of the loads discussed under 833.4(c) (wind, etc.)? Reply (11: No. Subparagraph 833.4(c) is intended to limit the sum of longitudinal bending stresses resulting from externally applied "primary" loadings, from whatever source. It is not intended to apply to stresses resulting from self-limiting, secondary displacement strains. Wind and wave action that acts on the pipe itself is an externally applied "primary" loading and must be included in 833.4(c). However, wind and wave action that is applied to an offshore platform causes a predictable displacement of the platform which is limited by the design of the platform. Movement of the platform imposes displacements on the piping restraints and supports which is similar to thermal effects. These displacements must be included with thermal effects in flexibility and expansion analysis. Question (2): If so, can the allowable stress for 833.4(b) and (c) be increased to a higher value as per ANSIIASME 031.4? Reply (2): No. There are no increases permitted in the allowable stresses specified in and ASMEIANSI and have no bearing on 833 of ANSIIASME Question (3): As per ASMEIANSI 031.3, the deflection effects are to be considered together with thermal effects for displacement stress range computation only. Does this apply to ANSIIASME stress range computation also? Reply (3): Yes. Secondary stresses resulting from externally imposed fixed displacements should be included with the calculation of expansion stresses covered in and 833.4(a). Question (4): Occasionally some clients interpret that the expansion stress (secondary stress) as per ANSIIASME for construction type C shall not exceed 0.5s. Does the allowable expansion stress require adjustment based on construction type? Reply (4): No. Question (5): Are there any adjustments to the allowable limits for the total longitudinal stress computed per 833.4(a), (b), and (c) to reflect the construction type? Reply (5): The longitudinal pressure stress calculated in 833.4(b) must be adjusted for the construction type design factor.

18 l nterpretations No. 6 Replies to Technical Inquiries April 1, 1989, Through August 31, 1989 It has been agreed to publish interpretations issued by the 831 Committee concerning as part of the update service to the Code. The interpretations have been assigned interpretation numbers in chronological order. Each interpretation applies 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 may have superseded the reply. The interpretations are not 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. 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.

19 831.8 Interpretations No. 6 Interpretation: 6-1 Subject: ANSIIASME B31.8, Paras (b) and (g), Qualification of Steel Pipe Date Issued: April 5, 1989 File: Question: For qualification of used steel pipe or unidentified new steel pipe for use at stress levels above 6000 psi, ANSIIASME specifies the following requirements (in addition to others): (i) flattening test for pipes larger than NPS 2 [reference para (b)]; (ii) yield-tensile ratio less than or equal to 0.85 [reference para (g)]. Can it be interpreted from the above that for new pipes ordered as per a 'Code' approved standard (e.g. API 5L), the above requirements should be specified as additional requirements, in the event they are not mandatory requirements, for a particular type or grade of steel pipe? Reply: No. Interpretation: 6-2 Subject: ANSIIASME B31.8, Requirements for Compressed Air Piping Systems Date Issued: June 22, 1989 File: Question: Does ANSIIASME B31.8 cover piping systems for compressed air systems, such as those used in industrial automation, robotics, and air driven tools? Reply: No. You are directed to the Scope sections of B31.I (para ), B31.3 [para l(b)], and (para ) which may be suitable for your application. You may wish to also review the requirements of Chapter VII in B31.3 on nonmetallic pipe.

20 831.8 Interpretations No. 6 Interpretation: 6-3 Subject: ANSIIASME 831.8, Para (f), Design of Flow Lines Date Issued: August 17, 1989 File: Question (1): ANSIIASME 831.8's para (0 states that this Code does not apply to flow lines between wellheads and traps or separators. Many flow lines in the oil field have been designed using the design formula from this Code under para. 841.I 1 (a). What is the intent of this exclusion? Reply (1 ): The original intent of excluding flow lines from is unknown; however, the intent of is to cover field gathering pipelines, transmission lines, and distribution systems. See Fig. 18, Appendix I. Question (2): If is not the appropriate Code for flow line design, what is? Reply (2): See 831 Code Case 137, Piping Not Covered by Any ANSIIASME 831 Section, for guidance. Interpretation: 6-4 Subject: ANSIIASME 831.8, Paras (g) and , Exclusion from Scope- Instrument Piping Date Issued: August 2 1, File: E Question: Does ANSIIASME require that the pressure-containing portion of an in-line sensing device be designed, fabricated, examined, and tested in accordance with the rules of ANSIIASME Reply: Yes.

21 Interpretations No. 6 Interpretation: 6-5 Subject: ANSIIASME 831.8, Para. 840.l(a), Maximum Allowable Stress for Buried Pipe Subject to Ground Movement Date Issued: August 2 1, 1989 File: Question: Under the requirements of ANSIIASME 831.8, what is the maximum allowable stress for buried gas pipelines subject to movement at active ground faults? Reply: The Code does not specifically indicate the maximum allowable stresses in buried gas pipelines resulting from catastrophic events such as movement at fault crossings. See para (a). Interpretation: 6-6 Subject: ANSI IASME B3 1.8, Para , Limits of Compressor Station Piping Date Issued: August 22, 1989 File: B Question (1): Under the requirements of ANSIIASME B31.8, what is the basis of using Type C construction for compressor stations? Reply (1 1: Table A. Question (2): Is Type C construction related to reciprocating compressor stations? Reply (2): Type C construction applies to all types of compressor stations including reciprocating. Question (3): What is the breakpoint for Type C construction? Reply (3): The station suction and discharge valves if the station is located in Location Classes 1, 2; or 3. See para Question (4): Under the requirements of ANSIIASME does compressor station piping, Type C, apply from the suction valve to the discharge valve? Reply (4): Type C construction applies from the station (not the compressor unit) suction valve to the station (not the compressor unit) discharge valve. See para

22 6-7 Interpretation: Interpretations No. 6,-- -. '\ Subject: ANSIIASME 831.8, Para and Table SA, Limits of Compressor Station Piping Date Issued: August 23, 1989 File: B Question (11: Under the requirements of ANSIIASME 831.8, Para and Table A, is Type C construction only limited up to the discharge valve of the individual compressor units, and Type 8 construction limited to the combined suction and discharge line of a compressor station? Reply (11: No. Type C construction applies from the station (not the compressor unit) suction valve to the station (not the compressor unit) discharge valve. Question (2): If new piping is added upstream of the discharge fire gate, of an existing compressor station for incorporation of gas cooling equipment, is such piping required to be of Type C construction? Reply (2): Yes. Question (3): Do the requirements of Para and Table A limit Type C construction to compressor stations having reciprocating compressor units, or do they include compressor stations having centrifugal compressors as well? Reply (3): Type C construction applies to all types of compressor stations including reciprocating and centrifugal.

23 INTERPRETATIONS NO. 7 Replies to Technical Inquiries September 1, 1989, Through August 31, 1990 It has been agreed to publish interpretations issued by the 831 Committee concerning as part of the update service to the Code. The interpretations have been assigned interpretation 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 may have superseded the reply. The interpretations are not 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. 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.

24 831.8 lnterpretations No.7 Interpretation: 7-1 Subject: Hydrotest Preparation Date Issued: June, 12, 1987 File: Question: May all joints, including welds, used in piping systems covered by ANSVASME B31.I, ANSIIASME 831.3, ANSIIASME 831.4, ANSIIASME 831.8, ANSVASME B31.9, and ANSIIASME 831.I 1 be primed and painted prior to hydrotest? Reply: Yes. Note: This interpretation was inadvertently omitted from Interpretations No. 5, which includes interpretations issued from February 1, 1987, through December 31, Interpretation: 7-2 Subject: Paras. 841.I 1 (a) and 841.I 21 (f), Mimimum Yield Strength Date Issued: February 26, 1990 File: Question: Is it permissible under the requirements of para. 841.I21 (f) in ANSIIASME to use an actual yield strength value that is less but not greater than the specified minimum yield strength as stipulated in the specification? Reply: Yes.

25 831.8 Interpretations No. 7 Interpretation: 7-3 Subject: Para , Welder Qualification Test Date Issued: February 26, 1990 File: B Question (1 ): Under the requirements of ANSIIASME 831.8, para , is it permissible to test the welder to API but ignore the results of tensile and nick-break tests? Reply (1): No. Question (2): Under the same paragraph in Question (I), is it permissible to test the welder to API 1104 but using only six bend tests instead of two tensile, two nick, and two root bend tests? Reply (2): No. Question (3): Under the same paragraph in Question (I), is it permissible to test the welder to API but use Appendix G of ANSIIASME B31.8 to test the straps? Reply (3): No. Question (4): If Reply (3) is no, are there some other requirements than those questioned in (11, (21, and (3)? Reply (4): Yes. Test the welder to the provisions of API 1104 including the guided bend tests. Interpretation: 7-4 Subject: Para , Setting of Pressure Relief Valves Date Issued: March 7, 1990 File: Question: Under the requirements of ASME B31.8, para , can a safety relief valve be set at any pressure between the maximum allowable operating pressure (MA0P)and 110% of the maximum allowable operating pressure for compressor station piping? Reply: Yes. The safety relief valve can be set at any point which will assure the operating pressure of the compressor and discharge piping will not exceed the maximum allowable operating pressure by more than 10%.

26 INTERPRETATIONS NO. 8 Replies to Technical Inquiries September 1, 1990, Through August 31, 1991 Interpretations 8-1 Through 8-8 It has been agreed to publish interpretations issued by the B31 Committee concerning B31.8 as part of the update service to the Code. The interpretations have been assigned interpretation 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 may have superseded the reply. The interpretations are not 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. ASME procedures provide for reconsideration of these interpretations when or if additional information is available which the inquirer believes mlght 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.

27 831.8 Interpretations No. 8 Interpretation: 8-1 Subject: ASME B31.8, Para. 802, Applicability to Bypass Lines Date Issued: November 21, 1990 File: B Question (1): Does ASME B31.8 apply to bypass lines around pipeline block valves? Reply (1): Yes. Question (2): Does ASME B31.8 apply to bypass lines which operate at temperatures as low as - 46"C? Reply (2): No. ASME B31.8 is not applicable to piping with metal temperatures below -20 F. [See para (b).] Interpretation: 8-2 Subject: ASME B31.8, Para , Plastic Pipe and Tubing Design Formula Date Issued: March 4, 1991 ) File: B Question: Based on the attached derivation, should not the design formula for plastic pipe and tubing in para be Reply: No. The formula found in the Code is based on an International Standards Organization (ISO) equation. See ASTM D b Interpretation: 8-3 Subject: Design of Scraper Traps Date Issued: April 9, 1991 File: B Question (1): Can a barrel of a scrapper trap be designed in accordance with ASME B31.8? Reply (1): Yes. Question (2): Can Appendix 24, ASME Section VIII, Division 1 be applied to the design for the end closure, when the clamp type connection is applied to the end closure of the scraper trap? Reply (2): Yes.

28 831.8 Interpretations No. 8 Interpretation: 8-4 Subject: ASME B Edition, Paras and (c), Inspection of Welds and Testing After Construction Date Issued: April 9, 1991 File: B Question (1): Does para exempt a piping system intended to operate at 1440 psig with material having a specified minimum yield strength of 35,000 psi from radiographic or other NDE? Reply (1): Paragraph would apply only if the hoop stress S, is less than 20% of the SMYS; otherwise, para would apply. Question (2): Under para (c), would pipelines and mains in Location Class 2 require testing at 1.25 times MOP regardless of hoop stress? Reply (2): Yes. Interpretation: 8-5 Subject: ASME B Edition, Para and Appendix E, Stress Intersification Factor Date Issued: April 9, 1991 File: B Question: When determining the expansion stress as defined by para , may the in-plane ii and out-plane i, intensification factors be used rather than the more conservative stress intensification factor i? Reply: Yes. See Notes (1) and (2) of Table E-1. Interpretation: 8-6 Subject: ASME B Edition, Para (b), Use of Buttwelding Fittings With Nonstandard Dimensions Date Issued: June 23, 1991 File: B Question: Do reducers or reducing outlet tees that have nonstandard dimensions and are in "partial compliance" with ANSI B16.9 or MSS SP-75 fulfill the requirements of ASME B31.8? Reply: Yes, provided the requirements of paras and are met.

29 831.8 Interpretations No. 8 Interpretation: 8-7 Subject: Paragraph 840.2(b) and Tables A and B, Definition of Location Class 1, Division 1 Date Issued: June 23, 1991 File: B Question: Table A, Basic Design Factor F, identifies a Location Class 1, Division 1, and an associated design factor Table B, Design Factors for Steel Pipe Construction, lists the type of facility and the associated location class for pipelines, etc. Paragraph 840.2(b) is referenced. I have Addenda through January 15, 1991 for the 1989 Edition. However, I cannot find any reference wherein Division 1 and Division 2 are differently defined for Location Class 1. Could you please point out the proper paragraph. I would appreciate it very much. Reply: Paragraph 840.2(b) is being revised to include definitions of Location Class 1 Division 1 and Location Class 1 Division 2. The proposed definitions are presently going through the ASME approval process before publication. Interpretation: 8-8 Subject: Welding Terminology 1 Date Issued: June 24, 1991 File: B Question (1): What is meant by "longitudinal joint factor E" of Table 841.1B? Reply (1): In ASME B31.8a-1990 Addenda, the longitudinal joint rating factor is contained in Table A. The longitudinal joint factor is the term E in the design formula of para (a) used to compensate for the characteristic strength of a weld seam in a pipe. Question (2): What is the definition of "electric arc welding"? i Reply (2): Definitions of welding processes are contained in para The term "electric arc welding" is not defined. Both electric-fusion-welded pipe [para (c)] and double submerged-arc-welded pipe [para (e)] are produced using electric arc welding in which coalescence is produced by heating with a electric arc(s) between the metal electrode(s) and the work. Question (3): What is meant by "joint efficiency"? Reply (3): Joint efficiency is not defined even though para (d) is titled "Joint Efficiency." However, the terms "joint efficiency" and "longitudinal joint factor" mean the same thing.

30 INTERPRETATIONS NO, 9 Replies to Technical Inquiries September 1, 1991, Through August 31, 1992 Interpretation 9-1 It has been agreed to publish interpretations issued by the B31 Committee concerning B31.8 as part of the update service to the Code. The interpretations have been assigned interpretation 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 may have superseded the reply. The interpretations are not 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. 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.

31 831.8 Interpretations No. 9 Interpretation: 9-1 Subject: Paragraph , Wrinkle Bends Date Issued: August 31, 1992 File: B Question (1): First of all, please acknowledge if it is correct that ASME can give answers to any question on ANSI B31.8 since ANSI B31.8 has been developed by one of ASME's committees. Reply (1): This interpretation originates from the B31.8 committee directly and is in full accordance with the ASME policy on inquiries. Question (2): ANSI B31.8, para (a), states "all bends shall be free from buckling..." Please advise us of the definition of buckling and how buckling is different from wrinkle bends in para (f). Reply (2): There is no definition of buckling in B31.8. Paragraph (a) is intended to mean bends other than wrinkle bends. Question (3): ANSI B31.8, para (f) states: "Wrinkle bends shall be permitted only on systems operating at less than 30% of the specified minimum yield strength. When wrinkle bends are made in welded pipe, the longitudinal weld shall be located as nearly to 90 deg. with the top of the wrinkle as conditions will permit. Wrinkle bends with sharp kinks shall not be permitted. Wrinkles shall have a spacing not less than the distance equal to the diameter of the pipe measured along the crotch. On pipe NPS 16 and larger, the wrinkle shall not produce an angle of more than 1% deg. per wrinkle." (a) What is the definition of "wrinkle bends"? Is it wrinkles in bends which happen to exist unavoidably on intrados of the bends during the bending process, or is it one kind of bending method such as hot bend and cold bend? (b) What is the definition of "crotch"? Could you explain how to measure "the diameter of the pipe measured along the crotch" by a drawing? (c) It seems to be practically difficult to measure an angle of wrinkle. Could you recommend the method of measuring the angle of a wrinkle? (d) On pipe NPS 16 and larger, there is a permitted tolerance for the angle per wrinkle. How is it in the case of pipe under NPS 16? (e) Would you acknowledge the following specific case? "Pipe bend of material API 5L X46 seamless pipe can be permitted on systems operating at 1,250 psi even though it has wrinkles on intrados, if wrinkles meet the tolerances of spacing and angle specified in para (f)." We believe the above is correct, as 1,250 psi is less than 30% of the minimum yield strength of X46 pipe (1,250 psi < 46,000 psi x 30% = 13,800 psi). Reply (3): (a) A wrinkle bend as used in B31.8 is a bend in which the wrinkles are produced intentionally to secure a shorter radius bend. The use of such bends is restricted to systems operating at less than 30% of SMYS. It is not related to the method of bending. (b) The term crotch in para refers to the line along the inner curvature of a pipe bend. (c) The geometry of the individual wrinkle is not specifically measured. The language refers to the total angle of the bend divided by the number of visible wrinkles, i.e., the change in bend angle per wrinkle.

32 Interpretations No. 9 (d) Paragraph does not include a limit for the angle of a bend containing wrinkles L, in pipe smaller than NPS 16. (e) The example stated is incorrect. The internal pressure has been confused with the specified minimum yield strength of the bend material. The maximum allowable operating pressure of the example bend depends on its thickness and is 30% of the pressure calculated according to the equation in para Question (4): We understand that there is a separate standard ES-24 issued by PFI (Pipe Fabrication Institute) which specifies pipe bending methods, tolerances, processes, and material requirements. Please advise whether PFI Standard ES-24, para. 6.2, has any relation with ANSI B31.8, para (f). Reply (4): The PFI Standard ES-24 is not under the jurisdiction of ASME and we are unable to comment on how it is to be applied. Question (5): We would like to know whether there is any charge for your service. Reply (5): There is'no charge for the B31.8 Section Committee to provide interpretations of the B31.8 Code.

33 INTERPRETATIONS NO. 10 Replies to Technical Inquiries September 1, 1992, Through August 31, 1993 Interpretations 10-1 Through It has been agreed to publish interpretations issued by the B31 Committee concerning B31.8 as part of the update service to the Code. The interpretations have been assigned interpretation 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 may have superseded the reply. The interpretations are not 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. 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.

34 B31.8 Interpretations No. 10 Interpretation: 10-1 Subject: ASME B31G-1991 Date Issued: June 3, 1993 File: B Question: Does ASME B31G-1991 Manual for Determining the Remaining Strength of Corroded Pipelines cover all of the ASME B31 Codes for Pressure Piping? Reply: No. ASME B31G-1991 covers only ASME B31.4 Liquid Transportation Systems for Hydrocarbons, Liquid Petroleum Gas, Anhydrous Ammonia, and Alcohols; ASME B31.8 Gas Transmission and Distribution Piping %stems; and ASME B31.11 Slurry Transportation Piping Systems. Interpretation: 10-2 Subject: ASME B Edition, Duplex Stainless Steels Date Issued: June 7, 1993 File: B Question: Is the use of duplex stainless steel, such as ASTM A 790 Grade S31803, permitted by the rules of ASME B31.8? Reply: No. Interpretation: 10-3 Subject: ASME B Edition, Para (c) and Fig. F5, Reinforcement of Welded Branch Connections Date Issued: June 7, 1993 File: B Question (1): Is there an inconsistency between the definition of d as specified in ASME B Edition, para (c) and ASME B Edition, Fig. F5? Reply (1): Yes. The correct definition for d is "the length of the finished opening in the header wall measured parallel to the axis of the run" as shown in para (c). The definition of d in Fig. F5 is being corrected. Question (2): Does ASME B Edition include branch connections by insertion? Reply (2): No.

35 831.8 Interpretations No. 10 Interpretation: 104 Subject: ASME B Edition, Para , Location Class 4 Date Issued: June 7, 1993 File: B , B , B , B Question: Does ASME B Edition provide a numerical index for the description of "multistory buildings are prevalent" and "traffic is heavy or densey7 as stated in ASME B Edition, para ? Reply: No. Interpretation: 10-5 Subject: ASME B Edition, Paras and Date Issued: June 7, 1993 File: B Question (1): Does ASME B Edition state whether to use Division 1 or Division 2 in gas pipelines regions classified as Location Class l? Reply (1): No. The choice is made by the operating company. Question (2): Does ASME B Edition address the condition prescribed in para in sections of pipeline classified as Division 1 assuming an internal pressure that produces a hoop stress equivalent to 80% of the specified minimum yield strength? Reply (2): No.

36 831.8 Interpretations No. 10 Interpretation: 10-6 Subject: ASME B Edition, Platform Piping Date Issued: July 7, 1993 File: B Question (1): From two wellhead platforms, a 6 in. test line from a test manifold and an 18 in. production line from a production manifold transport gas to their respective separators on a productionlutility platform. These lines are installed on connecting bridges via a support platform. Is the ASME B Edition appropriate for the design of these lines crossing the connecting bridges? Reply (1): No. Per para (f), the Code does not apply to flow lines between wellhead and separator. Question (2): May the ASME B Edition be extended to design temperature below -20 F [para (b)J once the impact tests at the lowest design temperature are accepted according to specified requirements? Reply (2): No, per para (b), the Code does not apply to piping with metal temperatures below -20 F. Question (3): Is the design factor F = 0.6 acceptable for these lines (para ) [reference Question (I)]? Reply (3): The ASME B Edition does not apply to these lines. Interpretation: 10-7 Subject: ASME B Edition, Paragraph 827 Date Issued: August 2, 1993 File: B Question: (1): Does ASME B31.8, para. 827 allow only repair of defective welds in accordance with API 1104? Reply (1): No. Para. 827 also allows the removal of the defective weld. Question (2): Under para. 827, are welding procedures and welders qualified in accordance with the ASME BPV Code, Section IX per para also acceptable. Reply (2): Yes. Welding procedures and welders qualified per para are acceptable to repair defective welds in accordance with API 1104.