对接焊缝射线检测工艺规程NDT.doc

DOC. NO.：QCND-012 CONTROLLED UNCONTROLLED COPY NO.: RT EXAMINATION PROCEDURE543210陈鑫亮2015.01.06钱辉2015.01.06REV.NO.PREPARED BYAPPROVED BY NDE LEVEL ASME Pressure Vessel ProcedureDoc. No.QCND-014MT Examination ProcedureRev. No.5Page 12 / 51 General1.1 This procedure is applied to the x-ray radiographic examination of butt welds for pressure vessels constructed in accordance with ASME Code Section Div1, 2010 ED. and 2011 AD.1.2 This procedure shall be supplemented, when necessary, with the examination instructions defining more specific variables, which will be prepared by NDE Level personnel.2 Qualification of Examination Personnel 2.1 Any person engaged in radiographic examination shall be qualified and certified as a radiographic examiner in accordance with BAOSEs “Written Practice for NDE Personnel Training, Qualification and Certification”(QCND-011).2.2 The NDE Levelshall receive the necessary instruction or supervision from a certified NDE Level or Level Examiner. The NDE Level shall receive the instruction or supervision from a NDE Level Examiner.2.3 According to the respective responsibility range, all examiners shall complete the examination conforming to the referencing ASME Code Sections, standards and written instructions. They shall assure the working quality.3 Equipment, Tools and MaterialsThe LevelExaminer shall select the equipment, tools and materials to assure that they are in compliance with the following conditions and the requirement of the examination instruction.3.1 One of the x-ray equipment shall be selected from Table 1.Table 1TypeManufactureMax. TubeVoltage(KVp)Max. TubeCurrent(mA)Focal Size(mm2)Permitted max.Steel thickness(mm)XXQ1605Dandong16050.89XXG2505Dandong2505239XXQ3005Dandong30053.550XXH3205Dandong32053.5503.2 Film AGFA TESTIX C7 film shall be used in our Company. Depending on the x-ray penetration thickness, other suitable industrial radiographic film shall be selected. When using two films method, two different types of film shall be selected.3.3 Intensifying ScreenA suitable lead screen shall be selected from Table 2.3.4 Densitometer and Step Wedge Film The digital densitometer listed in Table 3 shall be used for judging radiograph density. The densitometer shall be checked against a calibrated step wedge film at least every 90 days by the NDE Level or Examiner, in accordance with T-262 of Section. The step wedge calibration film shall have been verified within the last year by the National Calibrating Measuring Center, with a national standard unless, prior to first use, it was maintained in a light-tight and waterproof sealed package as supplied by the manufacturer. Step wedge calibration film may be used without verification for one year upon opening, provided it is within the manufacturers stated shelf life.Table 2 Intensifying Screen Thickness (mm)Tube VoltageFrontBack6.49.5659.512.77612.719.08719.025.49825.438.110938.150.8111050.863.5121163.5100.013 For welds with reinforcements, the thickness on which the IQI is based is the nominal single wall thickness plus the estimated weld reinforcement not to exceed the maximum permitted by the Section Division 1. For welds without reinforcements, the thickness on which the IQI is based is the nominal single wall thickness. In both cases backing rings or strips shall not be considered as part of the weld thickness in IQI selection.3.5.3 Placement of IQIs The IQI(s) shall be placed on the source side of the part being examined. When configuration or size prevents placing the IQI(s) on the part or weld, the IQI(s) may be placed on a separate block in compliance with para. T-277.1 of Section V. The separate block shall be placed as close as possible to the part being radiographed. Where inaccessibility prevents hand placing the IQI(s) on the source side, the IQI(s) shall be placed on the film side in contact with the part being examined. A lead letter “F” shall be placed adjacent to or on the IQI(s). The IQI(s) shall be placed on the weld so that the length of the wires is perpendicular to the length of the weld. The identification number(s) and, when used, the lead letter “F” shall not be in the area of interest, except when geometric configuration makes it impractical.3.5.4 Number of IQIs When one or more film holders are used for an exposure, at least one IQI image shall appear on each radiograph. If the density of the radiograph anywhere through the area of interest varies by more than minus 15% or plus 30% from the density adjacent to the designated wire of a wire IQI, within the minimum/maximum allowable density ranges specified, then an additional IQI shall be used for each exceptional area or areas and the radiograph retaken. For cylindrical components or spherical components where the source is placed at the center of the component for a single exposure, at least three IQIs, spaced approximately 120deg. apart, are required.3.5.5 IQI Sensitivity Radiography shall be performed with a technique of sufficient sensitivity to display the essential wire of a wire IQI, which is essential indication of the image quality of the radiograph. The radiographs shall also display the identifying numbers and letters. If the essential wire do not show on any film in a multiple film technique, but do show in composite film viewing, interpretation shall be permitted only by composite film viewing.3.6 “B” Mark A lead symbol “B”, with minimum dimensions of 13mm in height and 1.6mm in thickness, shall be attached to the back of each film holder during each exposure to determine if backscatter radiation is exposing the film.3.7 Location Markers The image of the location markers for the coordination of the part with the film shall appear on the film without interfering with the interpretation, with such an arrangement that is evidence that complete coverage was obtained. Location markers shall be placed on the part, not on the exposure holder/cassette.3.7.1 Single-Wall Viewing(a) Source Side MarkersLocation markers shall be placed on the source side when radiographing the following: (1) Flat components or longitudinal joints in cylindrical or conical components will be according to Fig. 2.(2) Curved or spherical components whose concave side is toward the source and when the “source-to-material” distance is less than the inside radius of the component;(3) Curved or spherical components whose convex side is toward the source.(b) Film Side Markers(1) Location markers shall be placed on the film side when radiographing either curved or spherical components whose concave side is toward the source and when the “source-to-material” distance is greater than the inside radius.tDFilm Source side marker D: Source to material distance t：thickness of workpiece Fig 2(2) As an alternative to source side placement in 3.7.1(a), location markers may be placed on the film side when the radiograhp shows coverage beyond the location markers to the extent demonstrated by Fig.3, i.e. : Leff =（X+Mf+X）.(c) Either Side Markers Location markers may be placed on either the source side or film side when radiographing either curved or spherical components whose concave side is toward the source and the “source-to-material” distance equals the inside radius of the component. Fig.33.7.2 Double-wall viewing, at least one location marker shall be placed on the source side surface adjacent to the weld (or on the material in the area of interest) for each radiograph. 3.8 A system shall be used to produce permanent identification on the radiograph traceable to the contract, component, weld seam, or part numbers，as appropriate. On the radiograph, the following shall be plainly and permanently included and in any case this information shall not obscure the area of interest. (See Fig.4)(1) BAOSE (2)Job No. (3)Weld No. (4)Center mark. (5) Position No. (6)Repair mark, if used. (7)Location Marks. (8)Date of making radiograph7. Location Mark(Left) 1.Companys Name IQI 3.Weld No. 4. Center Mark 5.Position No. 6.Pepair Mark 7. Location Mark(Right)BAOSE A S T M 2.Job No. 8.Date of Making Radiograph Fig 43.9 Facilities for Viewing Radiographs 3.9.1 Illuminator used to view radiographs shall be verified that it has sufficient intensity to be visible for the essential wire diameter of IQI and can diffuse the light uniformly. When the radiograph is smaller than the viewing portion of illuminator or will include low density areas, the masks shall be provided to exclude any extraneous light.3.9.2 In order to obtain the necessary brightness through the radiograph at least 30cd/m2, the viewing equipment shall have the following illumination:Table 6Radiograph DensityMinimum Illumination2.03,000cd/m23.030,000 cd/m24.0300,000 cd/m23.10 Viewing Room Subdued background lighting shall be provided such that the intensity shall not cause troublesome reflection, shadows or glares on the radiograph.4 Check of Surface to be Radiographed Prior to starting of radiographic examination, the Examiner shall check or verify that the surface to be radiographed satisfies the following conditions.4.1 The reinforcement of butt welded joints is within the value specified in Section Division 1 as shown in Table 7.4.2 Any surface irregularities, such as weld ripples, splashing, undercut and surface roughness, cannot mask or be confused with the image of any discontinuity.Table 7NominalThickness mmMaximum Reinforcement mmCategory B & C Butt weldsOther Welds4.8134.02.413255153.25176647610266GENERAL NOTES:(a) For double welded butt joints, this limitation on reinforcement given above shall apply separately to both inside and outside surfaces of the joint.(b) For single welded butt joints, the reinforcement limits given above shall apply to the outside surface of the joint only.(c) Thickness of weld reinforcement shall be based on the thickness of the thinner of the materials being joined.(d) The weld reinforcement thickness shall be determined from the higher of the abutting surfaces involved.(e) Weld reinforcement may be removed if so desired.5 Setup for Exposure Level or level individual shall set up the equipment, tools and materials for exposure in accordance with the examination instruction so all requirements for radiograph will be met. The setup information shall be truly and clearly recorded as described in paragraph9.5.1 Arrangement of Film，IQI and Markers.5.1.1 Film cassette, IQI and markers shall be placed in accordance with Fig. 4. The Examiner who performs the exposure shall carefully insert the specified film into cassette and attach the “B” mark on its back.5.1.2 If the density of the radiograph anywhere through the area of interest varies by more than 15% or +30% from the density adjacent to the designated wire of a wire IQI within the minimum and maximum allowable density ranges specified in Table 8, then two IQIs shall be used. One shall be placed on the lightest area of interest and the other shall be placed on the darkest area of interest.5.2 Geometric Condition for Exposure.5.2.1 Source-to-object distance and distance from source side of object to the film shall meet the requirements of geometric unsharpness(Ug). The geometric unsharpness of radiograph shall not exceed what described in Table 9.Table 8 Acceptable Min &Max Density.Method of ViewingDensity of RadiographMinimumMaximumSingle1.84.0Composite1.34.0Each radiograph of a composite set shall have a minimum density of 1.3.Table 9 Acceptable Unsharpness (mm)Thickness of MaterialUg max 500.5150750.76751001.02The geometric unsharpness Ug of the radiograph shall be determined in accordance with: Ug = F*d/DWhere:F = source size: the max. projected dimension of the radiating source (or effective focal spot ) in the plane perpendicular to the distance D from the weld or object being radiographed.d= distance from source side surface of the weld or object being radiographed to the film.D= Distance from source of radiation to weld or object being radiographed.D and d shall be determined at the approximate center of the area of interest.5.2.2 The density and sensitivity within the effective viewing area for one film shall conform to the requirement specified. The effective examination length can be determined by means of method of actual examinations. 5.2.3 In general, the direction of the central beam of radiation shall be perpendicularly centered on the area of interest. When special defects need be detected, it shall be based on the examination instruction prepared by the Level Examiner.6 Film ProcessingThe Examiner shall develop the exposed films in accordance with the film processing procedure. The processing data shall be recorded. The chemical composition of developer and fixer, temperature and time shall be according to the recommended practice of the film manufacturer.6.1 Manual Processing Sequence The manual processing sequence see Tab10.Tab10 Film Processing SequenceSequencedevelopingStopbathingfixingwashingwettingdryingTime58(200C)115152030”15(600C)6.2 Processing Quality Requirements.The processed radiographs shall be free of mechanical, chemical or other blemishes. Such blemishes include, but are not limited to:a) fogging.b) processing defects such as streaks, water marks, or chemical stains.c) scratches, finger marks, crimps, static marks, smudges, or tears.d) loss of detail due to poor screen-to-film contact.e) false indications due to defective screens.7 Evaluation of Radiographs 7.1 Prior to evaluating the radiographs, the NDE level or shall check if the information in radiographing record and the exposure location drawing of the component or product are complete and correct.7.2 Prior to being interpreted, the radiographs shall be checked whether their own quality is conformed to the specified requirements. Otherwise, the radiograph has to be retaken.7.3 In addition to the requirement described in Paragraph 6.2, the requirement of radiograph quality also includes:7.3.1 Density Limitation The transmitted film density near the discernible minimum wire of an IQI on radiograph and the area to be interpreted shall be within the limitations specified in Table “B” Mark. The bright image of “B” mark shall not appear on a darker background of the radiograph. If dark image of “B” appears on the lighter background, it should not be taken as a reason that radiograph quality is unaccepted.7.3.3 IQI The IQI images and designated wire of wire IQI specified shall appear on the radiograph so asto ensure the quality level of inspection meeting the requirement of Table T-276 of Section .8 Acceptance Standards8.1 Acceptance standards for the radiographic examination of welds shall refer the ASME Code Section Div.1,UW-51(full RT) and UW-52(spot RT)for pressure Vessels.8.2 Indications shown on the radiographs of welds and characterized as imperfections are unacceptable for pressure vessel welds that are full radiographed under the following conditions . a) Any indication characterized as a crack or zone of incomplete fusion or penetration. b) Any other elongated indication on the radiograph which has a length greater than:6mm for t up to 19mm1/3 t for t from 19mm to 57mm19mm for t over 57mm where t is the thickness of the weld excluding any allowable reinforcement.c) Any group of aligned indications that have an aggregate length greater than t in a length of 12t, except when the distance between the successive imperfections exceeds 6L.L is the length of the longest imperfection in the group.d) Rounded indications