1、Designation:A531/A531M91 (Reapproved 2006) Designation: A531/A531M 12Standard Practice forUltrasonic Examination of Turbine-Generator Steel RetainingRings1This standard is issued under the fixed designation A531/A531M; the number immediately following the designation indicates the yearof original ad
2、option or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1This practice covers the procedures to be followed when performing ultr
3、asonic shear and longitudinal wave tests onturbine-generator retaining rings with an inside diameter to wall thickness ratio equal to or greater than 5:1 and with wallthicknesses from 1 to 4 in. (25 to 102 mm).1.2Although this practice describes methods of ultrasonically testing retaining rings by e
4、ither the contact or immersion method,it shall not restrict the use of improved inspection methods as they are developed. It is recognized that techniques for examinationand evaluation may be chosen in order to enhance or improve the results or to accommodate variations in procedures, equipment,or c
5、apabilities. Considering these characteristics, forgings may be inspected by a combination of both the contact and theimmersion methods, as mutually agreed upon between the manufacturer and the purchaser.1.3This practice and the applicable material specifications are expressed in both inch-pound uni
6、ts and SI units. However, unlessthe order specifies the applicable “M” specification designation SI units, the material shall be furnished to inch-pound units.1.4 *1.1 This practice covers ultrasonic examination of turbine-generator retaining rings produced in accordance with SpecificationsA288 andA
7、289/A289M with an inside diameter to wall thickness ratio equal to or greater than 5:1 and with wall thicknesses from1 to 4 in. 25 to 102 mm.1.2 Forgings may be inspected by either the contact or the immersion methods, or combinations thereof, as agreed upon betweenthe manufacturer and the purchaser
8、.1.3 Supplementary requirements of an optional nature are provided for use at the option of the purchaser. The supplementaryrequirements shall apply only when specified individually by the purchaser in the purchase order or contract.1.4 This practice is expressed in inch-pound and SI units; however,
9、 unless the purchase order or contract specifies the applicable“M” specification designation (SI units), the inch-pound units shall apply. The values stated in either inch-pound units or SI unitsare to be regarded separately as standard. Within the practice, the SI units are shown in brackets. The v
10、alues stated in each systemmay not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the twosystems may result in nonconformance with the standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated w
11、ith its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A288 Specification for Carbon and Alloy Steel Forgings for Magnetic
12、Retaining Rings for Turbine GeneratorsA289/A289M Specification for Alloy Steel Forgings for Nonmagnetic Retaining Rings for GeneratorsE127 Practice for Fabricating and Checking Aluminum Alloy Ultrasonic Standard Reference Blocks Practice for Fabricatingand Checking Aluminum Alloy Ultrasonic Standard
13、 Reference BlocksE317 Practice for Evaluating Performance Characteristics of Ultrasonic Pulse-Echo Testing Instruments and Systems withoutthe Use of Electronic Measurement Instruments2.2 Other Document:1This practice is under the jurisdiction of ASTM Committee A01 on Steel, Stainless Steel and Relat
14、ed Alloys and is the direct responsibility of Subcommittee A01.06on Steel Forgings and Billets.Current edition approved March 1, 2006.2012. Published April 2006.March 2012. Originally approved in 1965. Last previous edition approved in 20012006 asA531/A531M 91 (2001).(2006). DOI: 10.1520/A0531_A0531
15、M-91R06.10.1520/A0531_A0531M-12.2For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.1This document is not an ASTM
16、standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all
17、cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Recommended
18、 Practice for Nondestructive Personnel Qualification and Certification SNT-TC-1A,Supplement C-UltrasonicTestingOther Documents:Recommended Practice No. SNT-TC-1A Personnel Qualification and Certification in Nondestructive Testing33. Personnel Requirements3.1The manufacturer shall be responsible for
19、assigning qualified personnel to perform ultrasonic examination in conformancewith the requirements of this practice.3.2Personnel performing ultrasonic examinations in accordance with this practice shall be familiar with the following:3.2.1Ultrasonic terminology,3.2.2Instrument calibration,3.2.3Effe
20、ct of transducer material, size, frequency, and mode on test results,3.2.4Effect of material structure (grain size, cleanliness, etc.) on test results,3.2.5Effect of test distance on test results,3.2.6Effect of nonlinearity on test results,3.2.7Effect of thickness and orientation of discontinuities
21、on test results, and3.2.8Effect of surface roughness on test results.3.3A qualification record (see Note 1) of personnel considered suitable by the manufacturer to perform examination inaccordance with this practice shall be available upon request.NOTE1SNT-TC-1 A, Ultrasonic Testing Method, provides
22、 a recommended procedure for qualifying personnel. Other personnel qualificationrequirement documents may be used when agreed upon between the purchaser and supplier.3.1 Personnel performing ultrasonic examinations to this practice shall be qualified and certified in accordance with a writtenprocedu
23、re conforming to Recommended Practice No. SNT-TC-1A or other national standard acceptable to both the purchaser andthe supplier.4. Ordering Information4.1 When this practice is to be applied to an inquiry, contract, or order, the purchaser shall so state and shall also furnish thefollowing informati
24、on:4.1.1 The method or combination of methods to be used for inspection.4.1.2 The frequency to be used for conducting each inspection.4.1.3 Report requirements including C-scan plot, if applicable.4.1.4 Supplementary requirements, if any.5. General Requirements5.1 As far as possible the entire volum
25、e of the retaining rings shall be subject to ultrasonic inspection. Circumferential and axialfaces shall be machined flat and parallel to one another.5.2 The ultrasonic inspection shall be performed after final processing and heat treatment for properties, unless otherwisespecified in the order or c
26、ontract.5.3 Rings may be tested either stationary (contact) or while rotating (immersion). If not specified by the purchaser, acombination of methods may be used at the manufacturers option. Scanning speed shall not exceed 6 in./s (152 mm/s),15 cm/s,unless automatic recording (C-scan) equipment is e
27、mployed.5.4 To ensure complete coverage (during contact testing), the search unit shall be indexed approximatelyno more than 75 % ofthe transducer width with each pass of the search unit. During immersion testing establish a transducer index adjustment whichwill ensure complete coverage with suffici
28、ent overlap.5.5 During the testing, a combination of methods and frequencies of 1 MHz, 214 MHz, and 5 MHz may be used for accuratelylocating, determining orientation, and defining specific discontinuities detected during overall scanning.5.6 For reporting purpose, location of indications shall be ci
29、rcumferentially defined by clock position. The test notch or a similarlocator, such as a reference line bisecting the serial number, shall be used to define and identify the 12 oclock position.6. Apparatus6.1 Ultrasonic, Pulsed, Reflection Type of Instrument, shall be used for the examination. The s
30、ystem shall have a minimumcapability for examining at frequencies from 1 to 5 MHz.6.1.1The amplifier and the cathode ray tube shall provide linear response (within 5%) for at least 75% of the screen height(sweep line to top of screen).6.1.2The instrument shall contain a calibrated gain control or si
31、gnal attenuator (in each case, accurate within 65%) that willallow indications beyond the linear range of the instrument to be measured.3Available from the American Society for Nondestructive Testing, 914 Chicago Ave., Evanston, IL 60202.A531/A531M 1226.1.3When the immersion method of inspection is
32、employed, suitable equipment must be available so that the retaining ringscan be immersed in a liquid coupling agent or can be subject to inspection by the use of a column or stream of the couplant throughan appropriate container attached to the part or transducer. Equipment must also include fixtur
33、ing for smooth mechanical rotationof the part or the transducer during scanning. Electronic ApparatusA pulse-echo instrument permitting inspection frequenciesof 1, 2.25, and 5 MHz is required. The accuracy of discontinuity amplitude analysis using this practice involves a knowledge ofthe true operat
34、ing frequency of the complete inspection system. One of the best ways to obtain the desired accuracy is by use ofa tuned pulser and narrow band amplifier of known frequency response, with either a broadband transducer, or a narrow-band tunedtransducer of known and matching frequency.6.1.1 Apparatus
35、Qualification and CalibrationBasic qualification of the ultrasonic test instrument shall be performed atintervals not to exceed 12 months or whenever maintenance is performed that affects the equipment function. The date of the lastcalibration and the date of the next required calibration shall be d
36、isplayed on the test equipment.6.1.2 The horizontal linearity shall be checked on a distance calibration bar using the multiple order technique (see PracticeE317). The horizontal linearity shall be 62 % of the metal path.6.1.3 The accuracy of the linearity shall be checked by ultrasonically verifyin
37、g the thickness of the component in at least onelocation beyond the near field of the transducer. If necessary, minor adjustments for differences in the ultrasonic velocities betweenthe calibration bar and the forging shall then be made.6.1.4 When the immersion method of inspection is employed, suit
38、able equipment must be available so that the retaining ringscan be immersed in a liquid coupling agent or can be subject to inspection by the use of a column or stream of the couplant throughan appropriate container attached to the part or transducer. Equipment must also include fixturing for smooth
39、 mechanical rotationof the part or the transducer during scanning.6.2 AmplifierThe amplifier and display shall provide linear response within 62 %, up to 100 % of full screen height.6.2.1 Amplifier CalibrationAn amplifier vertical linearity check shall be made prior to performing the test by observi
40、ng amultiple order pattern from a calibration block using a 2.25 MHz transducer (see Practice E317). The first back reflection shall beset at 100 % of full screen height. The higher order back reflections, 10 % and higher in amplitude, shall also be positioned onthe screen and their amplitudes noted
41、. The first back reflection shall be reduced to 50 % and then 25 % of full screen height. Theamplitudes of the higher order back reflections shall be noted at each step. The vertical linearity will be considered acceptable ifthe signal heights of the higher order reflections decrease in proportion t
42、o the decrease set for the first back reflection. Themaximum acceptable error for the decrease of the higher order reflections is the greater of 65 % of the expected back reflectionheight or 62 % of full screen height.6.3 Signal AttenuatorThe instrument shall contain a calibrated gain control or sig
43、nal attenuator that meets the requirementsof Practice E317 (in each case, accurate within 65 %) that will allow indications beyond the linear range of the instrument to bemeasured. It is recommended that these controls permit signal adjustments up to 25 to 1 (28 dB).6.4 Search Units:6.2.16.4.1 Conta
44、ct Method:6.2.1.1A6.4.1.1 A2.25 or 1.0-MHz, 45 angle beam shear wave search unit shall be employed for shear wave testing (2.25 MHzshall be used unless acoustic attenuation of the material is such that 1 MHz must be employed to obtain adequate penetration ofthe ring section). Adequate penetration is
45、 the ability to clearly resolve the calibration notch above resultant noise level.6.24.1.2 A 5, 2.25, or 1-MHz,34 to 118-in. (19.019.0 to 28.6-mm)28.6-mm diameter, longitudinal wave transducer shall beused for performing the longitudinal wave test.6.24.1.3 Acrylic resin shoes ground to the curvature
46、 of the retaining ring may be used to maintain the optimum contact anglebetween the transducer and outside diameter of the ring.6.24.1.4 When agreed upon between the purchaser and supplier, alternative test frequencies may be used to perform the requiredtests.6.2.26.4.2 Immersion Method:6.24.2.1 A5,
47、 2.25, or 1-MHz transducer,34 to 1 in. (19.019.0 to 25.4 mm)mm in diameter, suitable for water immersion, shallbe used for performing the required test.6.24.2.2 The manipulator (holder) for the search tube or transducer, or both, shall provide for angular manipulation of thetransducer for optimum re
48、sponse from the internal discontinuities. The tolerance or play present in the manipulation and in thetraversing unit should not be excessive so as to prevent ultrasonic examination at the required sensitivity level.6.24.2.3 When agreed upon between the purchaser and supplier, alternative test frequ
49、encies may be used to perform the requiredtests.6.2.2.46.4.2.4 Accessory EquipmentCoaxial cables and search tubes used in conjunction with the electronic apparatus capableof conducting the electrical pulses while immersed in a liquid, and collimators for shaping the sound beam may be used.6.35 Recording instruments or alarm systems, or both, may be used, provided sufficient range and sensitivity are available toproperly monitor the test.7. Preparation of the Forging for Ultrasonic Examination7.1 Surface roughness on the outside and inside diameter and radical
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