Welding of Pipelines and Related Facilities PDF

WELDING OF PIPELINES AND RELATED FACILITIES ‹ 53 2 mm -0/+0.5 mm ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ 1 mm NOTE HAZ hardness impressions shall be entirely within the heat-affected zone and located as close as possible to the fusion boundary (between the weld metal and heat-affected zone). Figure 25—Hardnes...

WELDING OF PIPELINES AND RELATED FACILITIES ‹ 53 2 mm -0/+0.5 mm ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ ‹ 1 mm NOTE HAZ hardness impressions shall be entirely within the heat-affected zone and located as close as possible to the fusion boundary (between the weld metal and heat-affected zone). Figure 25—Hardness Locations for Cover Pass Repair Procedure at Fusion Line 5 /64LQí1/64 in. PPíPP 3 /64 in. (1 mm) NOTE Heat-affected zone (HAZ) hardness impressions must be entirely within the HAZ and located as close as possible to the fusion boundary (between the weld metal and HAZ). Figure 26—Hardness Locations for Partial Thickness Repair at Fusion Line 10.3.7.4.3 Requirements The minimum average value and minimum individual value of impact energy for each set of three specimens when tested at the minimum design temperature shall not be less than the minimum values specified for qualification of the production weld or as otherwise specified by the company. 10.4 Repair Welder Qualification 10.4.1 General The repair weld shall be made by a qualified welder experienced in methods used for repair of a defective weld. The welder shall be qualified according to the requirements of 6.2 or 6.3 in addition to the requirements of this section. When a repair procedure is required by 10.2, a welder shall be qualified using the applicable qualified repair procedure. Welders shall be qualified using a completed weld to make a repair weld following all the details of the repair procedure. The repair weld shall be deposited in the fixed position on a segment of a full-circumference test weld for each repair type to be qualified in the location(s) specified by the company. The repair weld shall be a minimum of 8 in. (203 mm) in length to provide the necessary weld deposit for destructive testing. A single completed weld may be used to qualify more than one type of repair. 54 API STANDARD 1104 Table 6—Repair Weld Maximum Hardness Values, HV10 a Weld Metal Hardness Location Heat-affected Zone Root and Midthickness Cap Root and Midthickness Cap Sour service, any welding process Note b Note b Note b Note b Non-sour service, any welding process 275 c 275 275 325 Non-sour service, lowhydrogen welding process 275 275 350 350 NOTE The company may specify other maximum hardness values. a A lower load may be used for t he narrow heat-affected zones in some welds made by mechanized or automatic processes. b For sour service, see applicable governing standard or specification document. c 300 HV10 material 0.375 in. (9.5 mm) thick and above. Details of the repair welder qualification shall be recorded and maintained with the complete results of the qualification test for each type and location of repair to meet the requirements of 6.8. 10.4.2 Testing of Repairs For a repair welder qualification test weld, the repair weld shall meet the visual examination requirements of 6.4 and 10.3.7.2. The destructive testing requirements in 6.5 are for qualification of a repair welder, except that test specimens shall be cut from the joint at each individual repair area location for each type of repair. The total number of specimens and the test to which each shall be submitted are shown in Table 7. As noted in Table 7, when wall thickness is over 0.500 in. (12.7 mm), the side bend tests shall be substituted for face bend or root bend tests. Table 7—Type and Number of Butt Weld Test Specimens per Repair Type for Repair Welder Qualification Repair Type Tensile Strength Nick Break b Root Bend Face Bend Side Bend Total (Minimum) Full thickness 0 2 1a 1a 0 4 Internal partial thickness 0 2 1a 0 0 3 External partial thickness 0 2 0 1a 0 3 Cover pass 0 2 0 1a 0 3 Back weld 0 2 1a 0 0 3 a Side bend tests are substituted for face bend or root bend tests when wall thickness is over 0.500 in. (12.7 mm). b One nick break specimen is taken at the transition between the repair weld end and original weld bead and the second nick break specimen located at the midpoint of the repair weld deposit. A welder who fails to pass the repair welder qualification test(s) shall be permitted to retest as described in 6.7. WELDING OF PIPELINES AND RELATED FACILITIES 55 10.4.3 Qualification Limits A repair welder who has successfully completed the qualification test described in 10.4.3 shall be qualified within the limits of the essential variables described below. If any of the following essential variables are changed, the repair welder using a repair procedure shall be requalified: a) any change from one repair type to another, except when changing from a full thickness repair to any partial thickness repair; b) a change in filler metal group (see Table 1); c) an increase in depth of the repair area greater than two times the deposited repair weld thickness in the repair welder qualification test; d) a change in position from that for which the repair welder has already qualified (e.g. a change from flat to vertical or a change from vertical to horizontal or vice versa), except overhead position qualifies for all positions. 10.5 Supervision The repair shall be made under the supervision of an individual acceptable to the company who is experienced and knowledgeable in methods and procedures used for repairs. Inspection of repairs shall be performed as specified by the company. Welding inspection personnel shall meet the requirements of 8.3. Repairs shall be documented and maintained by the company. 10.6 Acceptance Criteria Repaired areas shall be inspected and evaluated by the same NDT methods previously used to determine a defect. Visual inspection is considered adequate when the defect was rejected by visual means and repaired by grinding without additional welding. NDT of a repair weld includes as a minimum the total repair area plus 10 % of the total repair weld length, or 2 in. (50 mm); whichever is longer on each side of the repair area. Repairs shall be considered acceptable when the repair area meets the standards of acceptability of Section 9 or more stringent acceptance criteria specified by the company. NOTE A repair weld of a weld originally inspected and rejected using alternative acceptance criteria derived in accordance with Annex A must be reinspected and meet the standards of acceptability of Section 9 or more stringent acceptance criteria as specified by the company. Repair of the total length of defect(s) rejected by Annex A alternative acceptance criteria is required. A partial length repair of a defect is prohibited. 11 Procedures for Nondestructive Testing (NDT) 11.1 Radiographic Test Methods 11.1.1 General Section 11.1 presents the requirements for producing radiographic images on film or other media through the use of Xrays or gamma rays. A detailed procedure for the production of images shall be established and recorded. Radiographic film produced by the use of this procedure shall have the density (see 11.1.10), clarity, and contrast required by this standard. Images produced by other systems shall have the requisite sensitivity to define clearly the essential wire diameter of the proper image quality indicator (IQI). The following criteria shall be used to evaluate images: a) an acceptable image quality that is free from fog and from processing irregularities that could mask the image of actual imperfections, 56 API STANDARD 1104 b) the prescribed IQI and the essential wire diameter, c) a satisfactory identification system, d) an acceptable technique and setup, e) compatibility with acceptance standards. All requirements that refer to the quality of the resulting images shall apply equally to X-rays and gamma rays. The use of radiographic testing and the frequency of its use shall be at the option of the company. The company and the radiographic contractor should agree on the radiographic procedure or procedures to be used prior to the performance of production radiography. The company shall require the contractor to demonstrate that the proposed procedures produce acceptable images and shall require the contractor to use such procedures for production radiography. 11.1.2 Details of Procedure 11.1.2.1 General The details of each radiographic procedure shall be recorded. A copy of the record shall be furnished to the company for its records. The record may be in the form of writing, a sketch, or both. As a minimum, each procedure shall include the applicable details listed in 11.1.2.2 and 11.1.2.3. 11.1.2.2 Film Radiography As a minimum, the procedure for film radiography shall include the following details. a) Radiation source—The type of radiation source, the size of the effective source or focal spot, and the voltage rating of the X-ray equipment. b) Intensifying screens—The type and placement of the screens and, if lead is used, their thickness. c) Film—The film brand or type or both and the number of film in the holder or cassette. For multiple-film techniques, the way in which the film is to be viewed shall be specified. d) Exposure geometry—Whether single-wall exposure for single-wall viewing (SWE/SWV), double-wall exposure for single-wall viewing (DWE/SWV), or double-wall exposure for double-wall viewing (DWE/DWV); the distance from the source or focal spot to the film; the relative positions of the film, weld, source, IQIs, and interval or reference markers; and the number of exposures required for radiography of a complete weld. e) Exposure conditions—Whether milliampere or curie minutes, the X-ray voltage or the input voltage and amperage, and the exposure time. f) Processing—Whether automatic or manual; the time and temperature for development and the time for stop bath or rinsing, fixing, and washing; and drying details. g) Materials—The type and thickness range of material for which the procedure is suitable. h) IQIs—The type of material, identifying ASTM or ISO set, and essential wire diameter. i) Heat shields—Material, thickness, and the distance from the film side of the heat shield to the pipe surface. WELDING OF PIPELINES AND RELATED FACILITIES 57 11.1.2.3 Other Imaging Media As a minimum, the procedure for radiography using imaging media other than film shall include the following details. a) Radiation source—The type of radiation source, the size of the effective source or focal spot, and the voltage rating of the X-ray equipment. b) The image collection system used. c) The image processing system used. d) The image viewing system used. e) The image storage system used. f) Exposure geometry—Whether SWE/SWV, DWE/SWV, or DWE/DWV; whether in motion or still imaging; the scanning speed for in motion imaging; the distance from the source or focal spot to the imager surface; the relative positions of the imager surface, weld, source, IQIs, and the intervals or reference markers; the amount of geometric magnification; the total magnification used for viewing; and the number of images required for radiography of a complete weld. g) Exposure conditions—Whether milliampere or curie minutes, the X-ray voltage or the input voltage and amperage, and when applicable, the exposure time. h) Materials—The type and thickness range of material for which the procedure is suitable. i) IQIs—The type of material, identifying ASTM or ISO set, and essential wire diameter. j) Heat shields—Material, thickness, and the distance from the imaging side of the heat shield to the pipe surface. 11.1.3 Exposure Geometry 11.1.3.1 Film Radiography When a radiographic source is centered in the pipe for exposing a butt weld, one exposure is adequate for the radiographic testing of the complete weld (SWE/SWV). When the radiographic source is outside but not more than 1/2 in. (13 mm) from the weld surface, at least three exposures separated by 120° shall be made for the radiographic testing of a complete weld (DWE/SWV). When the radiographic source is outside and more than 1/2 in. (13 mm) from the weld surface, at least four exposures separated by 90° shall be made for the radiographic testing of a complete weld (DWE/ SWV). When the OD of the piping containing the weld is 3.500 in. (88.9 mm) or less, a DWE/DWV procedure may be used. When this procedure is used and the radiation beam is offset so that the source-side and film-side portions of the weld do not overlap in the areas of the radiograph being evaluated, at least two exposures separated by 90° shall be made for the radiographic testing of a complete weld. When the source-side and film-side portions of the weld are superimposed, at least three exposures separated by 60° shall be made for the radiographic testing of a complete weld. When smaller diameter, thicker wall pipe is radiographed, additional exposures should be made to minimize the distortion of imperfection images at the ends of the radiographs. The minimum distance between the source or focal spot and the source side of the object being radiographed shall be determined by the following formula (using constant units of measurement): D = St ⁄ k 58 API STANDARD 1104 where D is the minimum distance, in inches (mm), between the source or focal spot and the source side of the object being radiographed; S is the size, in inches (mm), of the effective source or focal spot; t is the thickness of the weld, in inches (mm), including reinforcement, plus the distance between the film side of the weld and the film; k is the geometric unsharpness factor. When t is determined for SWE/SWV and DWE/SWV procedures, the thickness of the single wall and its weld reinforcement shall be used. When t is determined for DWE/DWV procedures, the OD of the weld (i.e. the OD of the pipe plus twice the average height of the weld crown) shall be used; k is defined as 0.02 in. (0.5 mm) for material with a thickness of less than or equal to 2.000 in. (50.8 mm). 11.1.3.2 Other Imaging Media For in-motion imaging, the exposure geometry shall be evaluated at the maximum scanning speed to be used during the radiographic testing of the complete weld. 11.1.4 Type of IQIs IQIs shall conform to the requirements of either ASTM E747 or ISO 19232-1 wire IQI. The company shall define which type of IQI (ASTM or ISO) is to be used. The IQI shall be made of a material that is radiographically similar to the material being welded. 11.1.5 Selection of IQIs The IQI shall consist of either a series of six (6) wires for ASTM E747 wire type or a series of seven (7) wires for ISO 19232-1 wire type IQI, arranged in order of increasing diameter. The essential wire diameter to be used, based on the thickness of the weld is shown in Table 8 for ASTM E747 wire type IQI and Table 9 for ISO 19232-1 wire type IQI. At the option of the company, smaller wire diameter IQI than those specified above may be used, provided the required radiographic sensitivity is obtained. The radiographic images of the IQI identifying style number and ASTM set letter or ISO designation shall appear clearly. The image of the essential wire diameter shall appear clearly across the entire area of interest. NOTE For purposes of IQI selection, when the SWE/SWV or DWE/SWV technique is used, the thickness of the weld means specified wall thickness plus the weld reinforcement (internal plus external combined). When the "elliptical" DWE/DWV technique is used, the thickness of the weld means twice the specified wall thickness plus the single weld reinforcement (internal plus external combined). When the “superimposed” DWE/DWV technique is used, the thickness of the weld means twice the specified wall thickness plus twice the weld reinforcement (internal plus external combined). Table 8—Weld Thickness vs Diameter of ASTM E747 Wire Type IQI Weld Thickness Essential Wire Diameter ASTM Set Letter in. mm in. mm 0 to 0.250 0 to 6.4 0.008 0.20 A >0.250 to 0.375 >6.4 to 9.5 0.010 0.25 A or B >0.375 to 0.500 >9.5 to 12.7 0.013 0.33 B >0.500 to 0.750 >12.7 to 19.1 0.016 0.41 B >0.750 to 1.000 >19.1 to 25.4 0.020 0.51 B >1.000 to 2.000 >25.4 to 50.8 0.025 0.64 B WELDING OF PIPELINES AND RELATED FACILITIES 59 Table 9—Weld Thickness vs Diameter of ISO Wire Type IQI Weld Thickness Essential Wire Diameter Wire Identity in. mm in. mm 0 to 0.250 0 to 6.4 0.008 0.20 13 >0.250 to 0.375 >6.4 to 9.5 0.010 0.25 12 >0.375 to 0.500 >9.5 to 12.7 0.013 0.33 11 >0.500 to 0.750 >12.7 to 19.1 0.016 0.41 10 >0.750 to 1.000 >19.1 to 25.4 0.020 0.51 9 >1.000 to 2.000 >25.4 to 50.8 0.025 0.64 8 11.1.6 Placement of IQIs 11.1.6.1 Film The IQIs shall be placed as follows. a) When a complete weld is radiographed in a single exposure using a source inside the piping, at least four IQIs placed across the weld and spaced approximately equally around the circumference shall be used. For the DWE/ DWV procedure, one IQI shall be placed on the source side of the pipe and across the weld so that the essential wire image is superimposed onto the weld images. For the DWE/SWV or SWE/SWV procedures requiring multiple exposures or multiple films for complete inspection of the weld, and where the length of film to be interpreted is greater than 5 in. (130 mm), two IQIs placed across the weld and located on the film side shall be used. One shall be within 1 in. (25 mm) of the end of the film length to be interpreted and the other shall be at the center of the film. When the film length to be interpreted is 5 in. (130 mm) or less, one IQI shall be placed on the film side, across the weld and located at the center of the length to be interpreted. When a repaired weld is radiographed, an additional IQI shall be placed across each repaired area. b) When it is not practical to place an IQI on the weld due to weld configuration or size, the IQI may be placed on a separate block. Separate blocks shall be made of the same or radiographically similar material and may be used to facilitate IQI positioning. The thickness of the separate block material should be the same as the thickness of the weld. c) Heat shields—IQI may be placed on a heat shield rather than in contact with the pipe, provided that the acceptability of such IQI placement is demonstrated during procedure qualification. 11.1.6.2 Other Imaging Media For imaging media other than film, IQI placement shall be the same as that required by 11.1.6.1. The IQI may be placed above the surface of the pipe or held in position between the surface of the pipe and the imager by a fixture attached to the imager or scanning device. Acceptability of such IQI placement shall be demonstrated during procedure qualification. 11.1.7 Production Radiography Only Level II or III radiographers shall interpret the radiographic images of production welds. Radiographers shall report to the company all defects observed in the images unless the company requires that all imperfections observed be reported. The radiographer shall indicate whether the weld meets the requirements of Section 9. The company shall determine the final disposition of the weld. 60 API STANDARD 1104 11.1.8 Identification of Images Images shall be clearly identified by the use of lead numbers, lead letters, markers, or other identification so that the proper weld and any imperfections in it can be quickly and accurately located. The company may specify the identification procedure to be used. Whenever more than one image is used to inspect a weld, identification markers shall appear on each image and adjacent images shall overlap. The last reference marker on each end of the image shall appear on the appropriate adjacent images in a way that establishes that no part of the weld has been omitted. 11.1.9 Storage of Film and Other Imaging Media 11.1.9.1 Film All unexposed films shall be stored in a clean, dry place where the conditions will not detrimentally affect the emulsion. If any question arises about the condition of the unexposed film, sheets from the front and back of each package or a length of film equal to the circumference of each original roll shall be processed in the normal manner without exposure to light or radiation. If the processed film shows fog, the entire box or roll from which the test film was removed shall be discarded, unless additional tests prove that the remaining film in the box or roll is free from preexposure fog exceeding 0.30 H&D transmitted density for transparent-based film or 0.05 H&D reflected density for opaque-based film. NOTE H&D refers to the Hurter-Driffield method of defining quantitative blackening of the film. (Ferdinand Hurter and Vero Charles Driffield, “Photochemical Investigations and a New Method of Determination of the Sensitiveness of Photographic Plates,” J. Soc. Chem. Ind., May 31, 1890.) 11.1.9.2 Other Imaging Media Imaging media other than film shall be stored in strict accordance with the manufacturer’s recommendations. 11.1.10 Film Density 11.1.10.1 General Except for small localized areas caused by irregular weld configurations, the transmitted H&D density in the area of interest of transparent-based film shall not be less than 1.8 or greater than 4.0. The reflected H&D density for opaquebased film shall not be less than 0.5 nor greater than 1.5. Transmitted H&D densities through small localized areas may exceed these limits; however, minimum densities shall not be less than 1.5 and maximum densities shall not exceed 4.2; reflected H&D density shall not be less than 0.25 and shall not exceed 1.8. NOTE H&D refers to the Hurter-Driffield method of defining quantitative blackening of the film. (Ferdinand Hurter and Vero Charles Driffield, “Photochemical Investigations and a New Method of Determination of the Sensitiveness of Photographic Plates,” J. Soc. Chem. Ind., May 31, 1890.) 11.1.10.2 Film Viewing Equipment The viewing equipment (illuminator) shall be of the variable high intensity type and shall be capable of viewing film densities within the range specified in 11.1.10.1. It shall be equipped to prevent light, coming from around the outer edge of the radiograph or through low density portions of the radiograph, from interfering with interpretations. 11.1.10.3 Film Viewing Facilities Viewing facilities shall provide subdued background lighting of an intensity that will not cause troublesome reflections, shadows, or glare on the radiograph. WELDING OF PIPELINES AND RELATED FACILITIES 61 11.1.10.4 Image Processing When requested by the company, film or other imaging media shall be processed, handled, and stored so that the images are interpretable for at least three years after they are produced. 11.1.10.5 Image Processing Area The image processing area and all accessories shall be kept clean at all times. 11.1.10.6 Radiation Protection The radiographer shall be responsible for the protection and monitoring of every person working with or near radiation sources. The protection and monitoring shall comply with applicable federal, state, and local regulations. 11.2 Magnetic Particle Test Method When magnetic particle testing is specified by the company, a detailed written procedure for magnetic particle testing shall be established that meets the requirements of ASTM E709. The company and the NDT contractor should agree on the magnetic particle testing procedure or procedures prior to the performance of production testing. The company shall require the contractor to demonstrate that the proposed procedures will produce acceptable results and shall require the contractor to use such procedures for production testing. 11.3 Liquid Penetrant Test Method When liquid penetrant testing is specified by the company, a detailed written procedure for liquid penetrant testing shall be established that meets the requirements of ASTM E165. The company and the NDT contractor should agree on the liquid penetrant testing procedure or procedures prior to the performance of production testing. The company shall require the contractor to demonstrate that the proposed procedures will produce acceptable results and shall require the contractor to use such procedures for production testing. 11.4 Ultrasonic Test Methods 11.4.1 General When ultrasonic testing is specified by the company for the inspection of new and/or in-service circumferential butt welds, the requirements of this section shall apply. A detailed procedure for use of the individual ultrasonic techniques shall be established and recorded. The use of ultrasonic testing and the scope of its use shall be at the option of the company. The company and the ultrasonic contractor should agree on the ultrasonic procedures before the performance of production testing. The company shall require the ultrasonic contractor to demonstrate the proposed procedures to produce acceptable and accurate results and shall require the contractor to use such procedures for production testing. Caution is advised when this method is applied to in-service weld inspection due to potential parent material and surface imperfections that can interfere with the use of the ultrasonic technique. All surfaces to be ultrasonically scanned shall be in the uncoated condition. For new construction projects, the coating cutback (bare pipe length) at pipe ends necessary for ultrasonic scanning should be specified prior to the pipe being coated. Pipe seams should be ground flush with the pipe surface for the distance necessary for ultrasonic scanning. 62 API STANDARD 1104 11.4.2 Details of Procedure 11.4.2.1 General The details of each ultrasonic procedure shall be recorded. A copy of the record shall be furnished to the company for its records. The record shall be in the form of both writing and sketches. As a minimum, each procedure shall include the applicable details listed in 11.4.2.2. 11.4.2.2 Ultrasonic Procedure As a minimum the procedure for ultrasonic testing of welds shall include the following specific application details. a) Type of welds to be tested, joint preparation dimensions, and welding processes. b) Material type (i.e. size, grade, thickness, process of manufacturing per API 5L). c) Scanning surface preparation/condition. d) Stage at which examination is to be performed. e) Ultrasonic instrument/system and probes (i.e. manufacturer, type, size, etc.). f) Automatic or manual. g) Couplant. h) Testing technique: 1) angles, 2) frequencies (MHz), 3) temperatures and ranges, 4) scanning patterns and speeds, 5) reference datum and location markers (i.e. root face and circumferential locations). i) Reference standards—detail sketches showing plan view and cross-section view dimensions of production material reference standard blocks and all reference reflectors. j) Calibration requirements—the interval at which calibration of the instrument or system is required, the sequence of setup calibration prior to inspecting welds, including all standard calibration blocks to be used, the reference sensitivity reflectors to be used, the reference sensitivity-level setting [i.e. distance amplitude correction (DAC) or time-corrected gain (TCG)], and the intervals for verification of calibration settings. k) Scanning level—the sensitivity setting in decibels (dB) to be added to the reference sensitivity for scanning. l) Evaluation level—the level or height of echoes detected during scanning at which further evaluation is required and any sensitivity adjustment to be made before evaluating for acceptance or rejection. m) Recording of results—type of record (e.g. sketch, thermal printer, compact disc, etc.) and whether all reflectors or only unacceptable reflectors will be recorded. n) Ultrasonic examination report—an example of the examination reports.