Regulatory Guide 1.66

Nondestructive Examination of Tubular Products

ML13064A108
Person / Time
Issue date:	10/31/1973
From:	US Atomic Energy Commission (AEC)
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References
RG-1.066
Download: ML13064A108 (3)

"ujOctober 1973U.S. ATOMIC ENERGY COMMISSIONREGULATORYDIRECTORATE OF REGULATORY STANDARDSGUIDEREGULATORY GUIDE 1.66NONDESTRUCTIVE EXAMINATION OF TUBULAR PRODUCTSA. INTRObUCTIONGeneral Design Criterion 1, "Quality Standards andRecords," of Appendix A, "General Design Criteria forNuclear Power Plants," to 10 CFR Part 50, requires thatstructures, systems, and components important to safetyhe designed, fabricated, erected, and tested to qualitystandards commensurate with the importance of thesafety functions to be performed. Appendix B, "QualityAssurance Criteria for Nuclear Power Plants and FuelReprocessing Plants," to 10 CFR Part 50, requires thatnIeasures he established to assure materials control andcontrol of special process, and that proper testing beperformed. This guide describes a method ofimplementing these requirements acceptable to the AECRegulatory staff with regard to the nondestructiveexamination requirements for tubular products used for'mponents of the reactor coolant pressure boundaryA other -safety-related systems. This guide applies tolight-water-cooled reactors. The Advisory Committee onReactor Safeguards has been consulted concerning thisguide and has concurred in the regulatory postion.B. DISCUSSIONThe requirements for nondestructive examination ofwrought seamless tubular products used for componentsof nuclear power plants are specified in paragraphNB-2550 of Section 111, "Nuclear Power PlantComponents," American Society of MechanicalEngineers (ASME) Boiler and Pressure Vessel Code.'These code requirements cover the examination ofseveral product forms (pipe, tubing, flar~ges, fittings)under a single category, "Seamless and Welded (WithoutFiller Metal) Tubular Products and Fittings"' withoutspecifying the examination method to be used for each'Copies may be obtained from the American Society ofMechanical Engineers, United Engineering Center, 345 East 47thStreet, New York, New York 10017.product form. Instead, the code simply states that theproducts shall be examined by one of several methodslisted.The requirements for the specific examinationmethods mentioned in NB-2550 lack detail and needsupplementing. In practice, examination procedureswhich conform to these requirements have permitteddefects of unacceptable size in tubular products to goundetected because the defects were unfavorablyoriented for the examination procedure applied.To assure adequate control of quality for theproducts listed above, supplementary requirements havebeen incorporated in this guide which include theidentification of specific examination methods to beused for each product form and additional requirementsfor specific examination methods when appropriate.Ultrasonic Examination of Pipe and Tubing. Pipe andtubing should be examined by the ultrasonic methodusing the angle beam technique in both the axial andcircumferential directions. The ASME Coderequirements in NB-2550 supplemented by ASTME-213, "Standard Method for Ultrasonic Inspection ofMetal Pipe and Tubing for LongitudinalDiscontinuities,"2 provide a suitable basis for detectingaxial defects. However, no consensus standard exists fbithe detection of circumferential defects (found in pipemanufactured by processes such as extrusion, swaging.and tube reducing). Therefore, supplementaryrequirements for this purpose are included in this guide.The acceptance criteria for ultrasonic examinationare based on a comparison of ultrasonic indicationsreflected from discontinuities in the product withindications from standard defects in a referenue2Copies may be obtained from American Society forTesting and Materials, 1916 Race Street, Philadelphiai.Pennsylvania 19103.USAEC REGULATORY GUIDES Copies of published guides may be obtained by request indicating the divisionsdesired to the US. Atomic Energy Commission. Washington. D.C. 20545,Regulatory Guides are issued to describe and make available to the public Attention: Director of Regulatory Standards. Comments and suggestions formethods acceptable to the AEC Regulatory staff of implementing specific parts of improvemnnts in these guides ae encouraged and should be sent to the SecretaryTommission's regulations, to delineate techniques used by the staff in of the Commission. U.S. Atomic Energy Commission. Washington. D.C. 20545.uing specific problems or postulated accidents, or to provide guidance to Attention: Chief. Public Proceedings Staff.,,,;nts. Regulatory Guides are not substitutes for regulations and compliance-;th them is not required. Methods and solutions different from those set out in The guides are issued in the following ten broad divisions:the guides will be accepltable if they provide a basis for the findings requisite tothe issuance or continuance of a permit or license by the Commission. 1. Power Reactors 6. Products2. Research and Test Reactors 7. Transportation3. Fuels and Materials Facilities 8. Occupational HealthPublished guides wilt be revised periodically, as appropriate. to accommodate 4. Environmental and Siting 9. Antitrust Reviewcomments and to reflect new information or experience. .Materials and Plant Protect-or, 10. General specimen. The ASME Code requires that standarddefects be axial notches on the inside and outside of thereference specimen, for which optimum resolution isdeveloped tb, scanning in the transverse (circumferential)tdieclittor. l lowevet, transversw scanning is not ideal forresolving defects oriented in other directions. As aconsequence, when pipe or tubing is examined usingtransverse scanning and axial standard defects, defects ofunacceptable size with unfavorable orientation mayappear to be smaller than the reference standard andthus escape detection. To adequately detectcircuinferentia! defects, it is necessary to scan in theaxial directidn with equipment calibrated usingcircum icrent ial notches.lFurther, scanning should be performed in both axialand both circumferential directions for optimumdetection of defects oriented in directions not normal tothe ' surface. This four-way scanning may beaccomplished by separate passes of the pipe through theexamination equipment in each direction (back andforth) or by a single pass through equipment containingfour complete and independent channels ofinstrumentation.Eddy-Current Examination. Eddy-current examinationmay he used as an alternative to ultrasonic examinationfor thin-walled pipe and tubing. However, this methodshould be limited to materials with uniform magneticproper ties (variability in magnetic properties may resultfrom a variation in the degree of cold work in thematerial due to fabrication) and to pipe and tubing ofappropriate sizes and thicknesses. Since the limiting sizeand thickness may be affected by such variables as coildesign, frequency, material properties, andinstrunmentation, these limitations should be establishedby the ability to resolve standard notches on bothoutside and inside surface of the reference specimen.Examination of Fittings. To the degree feasible, fittingsshould be examined using a volumetric examinationmethod. Ultrasonic examination is preferred whenapplicable, but radiographic examination usingappropriate techniques will also detect unacceptabledefects. The use of these techniques may be limited bysize, product configuration, or material condition(coarse-grained stainless steel) in which case a surfaceexamination method (magnetic particle or liquidpenetrant) should be applied.C. REGULATORY POSITIONNondestructive examination applied to tubularproducts used for components of the reactor coolantpressure boundary and other safety-related systemswhich are designed for pressures in excess of 275 psig ortemperatures in excess of 2000F should be capable ofdetecting unacceptable defects regardless of defectshape, orientation, or location in the product.Accordingly, to the degree practical, the examinationsshould include methods that apply to the entire volumeof the product and should include techniques designed;to locate all types of defects. In particular, procedure&!for ultrasonic examination of pipe and tubing shouldprovide a sensitivity that will detect randomly orienteddefects that occasionally develop in pipe and tubingmanufactured by extrusion, swaging, or tube-reducingprocesses. To increase the probability of detecting suchdefects, the examination requirements for tubularproductsl' specified in the ASME Boiler and PressureCode, Section Ill, "Nuclear Power Plant Components,"'should be supplemented as follows:1. Required Examinationsa. Wrought seamless and welded (without fillermetal) pipe and tubing should be examined over theentire volume of the material by the ultrasonic methodin accordance with ASTM E-213, "Standard Method forUltrasonic Examination of Pipe and Tubing forLongitudinal Discontinuities, and paragraphs C.2. andC.3. below. Alternatively, eddy-current methods inaccordance with NB-2554, Section 7II, ASME Code, maybe used provided the material has uniform magneticproperties and the product is limited to sizes andthicknesses for which meaningful examination resultscan be obtained by eddy-current methods.b. Tubular products used for Class 1 vessel nozzlesshould be examined by the ultrasonic method inaccordance with NB-2552 or the radiographic method inaccordance with NB-2553 over the entire volume +imaterial and by the magnetic particle methodLaccordance with NB-2555 or the liquid penetrantmethod in !.-rnrint-A w,,ith NB-55 oi'n 1 externalsurfaces and all accessible internal surfaces.c. Wrought seamless fittings (including flanges andfittings machined from forgings and bars) should beexamined by the ultrasonic method in accordance withNB-2552 or the radiographic method in accordance withNB-2553 over the entire volume of the material forwhich meaningful examination results can be obtained.Fittings or sections of fittings for which meaningfulresults cannot be obtained by these methods because ofirregular geometry or size should be examined by themagnetic particle method in accordance with NB-2555or the liquid penetrant method in accordance withNB-2556 on all external surfaces and all accessibleinternal surfaces.d. Welded tubular products (with filler metaladded) should be examined in accordance withNB-2560, Section IIl of the ASME Code. When theoption for ultrasonic examination of finished weldedpipe is invoked as permitted by NB-2560, theexamination should also meet the requirements ofASTM E-213, "Standard Method for UltrasonicExamination of Metal Pipe and Tubing," and paragraphsC.2. and C.3. below.3 Piping of 2 inch nominal pipe size or less which meet:design requirements of NB-3673,Section III, ASME cod,exempted from the examination requirements.1.66-2 2. Ultrasonic Examinationa. The procedure for ultrasonic examinationshould provide a sensitivity which will consistentlydetect defects that produce indications equal to orgreater than the indications produced by standarddefects in the reference specimen described in paragraphC.3. below and, insofar as practical, should be capable ofdetecting such defects regardless of orientation. Productswith defects that produce indications in excess of thereference standards are unacceptable unless the defectsare eliminated or repaired.b. The techniques employed in ultrasonicexamination of pipe should include angle beam scanningin both transverse and both longitudinal directions.c. The rotation of the pipe and translation (feedhelix) of the search unit assembly should be mai,,ainedconstant and should be such that 10MW/, volumetriccoverage is assured in the longitudinal and r-knsversedirections.d. The calibration procedure for ultrasonicexaminations should be conducted in both transverseand both longitudinal directions and at the speed thatwill be used for acceptance examination of the piping.3. Reference SpecimenIn addition to the axial notches or grooves required.by NB-2552,Section III of the ASME Code, thereference specimen used for ultrasonic examination ofpiping should also contain transverse notches extendingcircumferentially on the inner and outer surfaces. Thetransverse notches should have the same dimensionalrequirements as the axial notches (e.g., length ofapproximately I inch or less depending on the diameter,a width not to exceed 1/16 inch, and a depth not greaterthan the larger of 0.004 inch or 5 percent of the nominalwall thickness). All standard notches should be separatedsufficiently to preclude any interference or amplificationof their respective indications.1.66-3