Welding of Pipelines and Related Facilities PDF

WELDING OF PIPELINES AND RELATED FACILITIES 23 C A B NOTE This figure is not drawn to scale. Radius of plunger, A = 1 ¾ in. (45 mm); radius of die, B = 2 /഼ സ ഽ in. (60 mm); width of die, C = 2 in. (50 mm). Figure 8—Jig for Guided-bend Tests approximately a 3/4 in. (19 mm) width and then machi...

WELDING OF PIPELINES AND RELATED FACILITIES 23 C A B NOTE This figure is not drawn to scale. Radius of plunger, A = 1 ¾ in. (45 mm); radius of die, B = 2 /഼ സ ഽ in. (60 mm); width of die, C = 2 in. (50 mm). Figure 8—Jig for Guided-bend Tests approximately a 3/4 in. (19 mm) width and then machined or ground to the 1/2 in. (13 mm) width. The sides shall be smooth and parallel. The cover and root bead reinforcements shall be removed flush with the surfaces of the specimen. 5.6.5.2 Method The side bend specimens shall be bent in a guided-bend test jig similar to that shown in Figure 8. Each specimen shall be placed on the die with the weld at midspan and with the face of the weld perpendicular to the gap. The plunger shall be forced into the gap until the curvature of the specimen is approximately U shaped. Alternate bend test fixtures with bend radii equal to or less than the radius specified in Figure 8 may be used at the discretion of the company. 5.6.5.3 Requirements Each side bend specimen shall meet the root and face bend test requirements specified in 5.6.4.3. For test weld diameter greater than 12 3/4 in. (323.9 mm), a single failed side bend specimen may be replaced with two additional specimens from locations adjacent to the failed specimen. If either of the replacement bend test specimens fails, the weld is considered unacceptable. 5.7 Welding of Test Joints—Fillet Welds To weld the test joint for a fillet weld, a fillet weld shall be made to one of the configurations shown in Figure 10, following all the details of the welding procedure specification. 24 API STANDARD 1104 See Note 1 Wall thickness t »8 in. (3 mm) maximum radius on all corners 1 Approximately 9 in. (230 mm) See Note 2 1»2 in. (13 mm) Width of specimen t Wall thickness NOTE 1 The weld reinforcement is removed from both faces flush with the surface of the specimen. NOTE 2 Specimens may be machine cut to a width of ½ in. (13 mm), or they may be oxygen cut to a width of approximately ¾ in. (19 mm) and then machined or ground smooth to a width of ½ in. (13 mm). Cut surfaces are smooth and parallel. Figure 9—Side Bend Test Specimen: Wall Thicknesses Greater than 0.500 in. (12.7 mm) 5.8 Testing of Welded Joints—Fillet Welds 5.8.1 Preparation To test the fillet-welded joint, test specimens shall be cut from the joint at the locations shown in Figure 10. At least four specimens shall be taken and prepared as shown in Figure 11. The specimens may be machine cut or oxygen cut. They should be at least 1 in. (25 mm) wide and long enough so that they can be broken in the weld. For pipes less than 2.375 in. (60.3 mm) in OD, specimens shall be cut from the same general location. It may be necessary to make two test welds to obtain the required number of test specimens; two specimens shall be removed from each of two test welds. The specimens shall be air cooled to ambient temperature prior to testing. 5.8.2 Method The fillet weld specimens shall be broken in the weld by any convenient method. 5.8.3 Requirements The exposed surfaces of each fillet weld specimen shall show complete penetration and fusion, and a) the greatest dimension of any gas pocket shall not exceed 1/16 in. (1.6 mm); b) the combined area of all gas pockets shall not exceed 2 % of the exposed surface area; c) slag inclusions shall not be more than 1/32 in. (0.8 mm) in depth and shall not be more than 1/8 in. (3 mm) or onehalf the specified wall thickness in length, whichever is smaller; and d) there shall be at least 1/2 in. (13 mm) separation between adjacent slag inclusions. The dimensions should be measured as shown in Figure 6. WELDING OF PIPELINES AND RELATED FACILITIES 25 Two specimens from crotch and two at 90 to crotch NOTE This figure shows the location of test specimens for joints with an OD greater than or equal to 2.375 in. (60.3 mm). For joints with an OD less than 2.375 in. (60.3 mm), specimens are cut from the same general location, but two specimens are removed from each of two test welds. Figure 10—Location of Nick Break Test Specimens: Fillet Weld Procedure and Welder Qualification Test Welds 1 in. (25 mm) approx. May be hacksaw notched Hacksaw cut Approx. 45° bevel Flame cut 1 in. (25 mm) approx. Hacksaw cut 1 in. (25 mm) approx. 2 in. (50 mm) approx. Approx. 30° bevel Flame cut 2 in. (50 mm) approx. Figure 11—Location of Nick Break Test Specimens: Fillet Weld Procedure and Welder Qualification Test Welds, Including Size-to-size Branch Connection Welder Qualification Test 26 API STANDARD 1104 6 Qualification of Welders 6.1 General The purpose of the welder qualification test is to determine the ability of welders to make sound butt or fillet welds using previously qualified procedures. Before any production welding is performed, welders shall be qualified according to the applicable requirements of 6.2 through 6.8. It is the intent of this standard that a welder who satisfactorily completes the procedure qualification test is a qualified welder, provided the number of test specimens required by 6.5 has been removed, tested, and meet the acceptance criteria of 5.6, for each welder. Prior to starting the qualification tests, the welder shall be allowed reasonable time to adjust the welding equipment to be used. The welder shall follow the requirements of the applicable qualified welding procedure specification. The qualification of welders shall be conducted in the presence of a representative acceptable to the company. A welder shall qualify for welding by performing a test on segments of pipe nipples or on full-size pipe nipples, as specified in 6.2.1. When segments of pipe nipples are used, they shall be supported so that typical flat, vertical, and overhead welds are produced. The essential variables associated with procedure and welder qualifications are not identical. The essential variables for welder qualification are specified in 6.2.2 and 6.3.2. 6.2 Single Qualification 6.2.1 General For qualification to a single weld procedure specification, a welder shall make a test weld using a qualified procedure to join pipe nipples or segments of pipe nipples. The welder shall make a butt weld in either the rolled or the fixed position. When the welder is qualifying in the fixed position, the axis of the pipe shall be horizontal, vertical, or inclined from horizontal at an angle of not more than 45°. A welder making a single-qualification test for branch connections, fillet welds, or other similar configurations shall follow the specific welding procedure specification. Changes in the essential variables described in 6.2.2 require requalification of the welder. The weld shall be acceptable if it meets the requirements of 6.4 and either 6.5 or 6.6. 6.2.2 Scope A welder who has successfully completed the qualification test described in 6.2.1 shall be qualified within the limits of the essential variables described below. If any of the following essential variables are changed, the welder shall be requalified using an applicable qualified procedure. a) A change from one welding process to another welding process or combination of processes, as follows: 1) a change from one welding process to a different welding process; or 2) a change in the combination of welding processes, unless the welder has qualified on separate qualification tests, using each of the welding processes that are to be used for the combination of welding processes. b) A change in the direction of welding from vertical uphill to vertical downhill or vice versa. WELDING OF PIPELINES AND RELATED FACILITIES 27 c) A change of filler metal classification from Group 1 or 2 to any other group or from any Group 3 through 9 to Group 1 or 2 (see Table 1). A change of filler metal classification not listed in Table 1 to any other filler metal classification or vice versa. d) A change from one specified OD group to another. These groups are defined as follows: 1) specified OD less than 2.375 in. (60.3 mm), 2) specified OD from 2.375 in. (60.3 mm) through 12.750 in. (323.9 mm), 3) specified OD greater than 12.750 in. (323.9 mm). e) A change from one specified wall thickness group to another. These groups are defined as follows: 1) specified pipe wall thickness less than 0.188 in. (4.8 mm), 2) specified pipe wall thickness from 0.188 in. (4.8 mm) through 0.750 in. (19.1 mm), 3) specified pipe wall thickness greater than 0.750 in. (19.1 mm). f) A change in position from that for which the welder has already qualified (e.g. a change from rolled to fixed or a change from vertical to horizontal or vice versa). A welder who qualifies in the fixed position shall also be qualified to perform rolled welds within the essential variables qualified. A welder who qualifies on a butt weld shall also be qualified to make lap fillet welds within the essential variables qualified. A welder who successfully passes a butt weld qualification test in the fixed position with the axis inclined 45° from horizontal shall be qualified to do butt welds and lap fillet welds in all positions. g) A change in the joint design (e.g. the elimination of a backing strip or a change from V bevel to U bevel). 6.3 Multiple Qualification 6.3.1 General For multiple qualification, a welder shall successfully complete the two tests described below, using qualified procedures. For the first test, the welder shall make a butt weld in the fixed position with the axis of the pipe either horizontal or inclined from horizontal at an angle of not more than 45°. This butt weld shall be made on pipe with an OD of at least 6.625 in. (168.3 mm) and with a wall thickness of at least 0.250 in. (6.4 mm) without a backing strip. The weld shall be acceptable if it meets the requirements of 6.4 and either 6.5 or 6.6. Specimens may be removed from the test weld at the locations shown in Figure 12, or they may be selected at the relative locations shown in Figure 12 but without reference to the top of the pipe, or they may be selected from locations that are spaced equidistantly around the entire pipe circumference. The sequence of adjacent specimen types shall be identical to that shown in Figure 12 for the various pipe diameters. Specimens shall not include the longitudinal weld. For the second test, the welder shall lay out, cut, fit, and weld a branch-on-pipe connection in which the specified diameters of the run and the branch pipes are equal. This test shall be performed with a pipe diameter of at least 6.625 in. (168.3 mm) and with a specified wall thickness of at least 0.250 in. (6.4 mm). A hole with specified diameter approximately equal to the inside diameter (ID) of the branch pipe shall be cut in the run. The weld shall be made with the run pipe axis horizontal and the branch pipe axis extending vertically downward from the run pipe. The completed weld shall exhibit complete penetration around the entire circumference. Completed root beads shall not contain any burn-through (BT) of more than 1/4 in. (6 mm). The sum of the maximum dimensions of separate unrepaired BTs in any continuous 12 in. (300 mm) length of weld shall not exceed 1/2 in. (13 mm). 28 API STANDARD 1104 Top of pipe Nick break Under 2.375 in. (60.3 mm) Top of pipe Root bend Root or side bend See Note 2 Nick break Top of pipe Tensile Nick break Root or side bend Nick break Root or side bend Greater than 4.500 in. (114.3 mm) Greater than or equal to 2.375 in. (60.3 mm) but less than or equal to 4.500 in. (114.3 mm); also, less than or equal to 4.500 in. (114.3 mm) when wall thickness is greater than 0.500 in. (12.7 mm) but less than or equal to 12.750 in. (323.9 mm) Root or side bend Nick break Tensile Top of pipe Root bend or side bend Tensile Nick break Nick break Tensile Face or side bend Greater than 12.750 in. (323.9 mm) Face or side bend Nick break Tensile Tensile Nick break Root or side bend NOTE 1 At the company’s option, the locations may be rotated, provided they are equally spaced around the pipe; however, specimens do not include the longitudinal weld. NOTE 2 One full-section tensile strength specimen may be used for pipe with an OD less than or equal to 1.315 in. (33.4 mm). Figure 12—Location of Test Butt Weld Specimens for Welder Qualification Test WELDING OF PIPELINES AND RELATED FACILITIES 29 Four nick break specimens shall be removed from the weld at the locations shown in Figure 10. They shall be prepared and tested in accordance with 5.8.1 and 5.8.2. The exposed surfaces shall meet the requirements of 5.8.3. 6.3.2 Scope A welder who has successfully completed the butt weld qualification test described in 6.3.1 on pipe with an OD greater than or equal to 12.750 in. (323.9 mm) and a branch weld with pipe and branch having specified ODs greater than or equal to 12.750 in. (323.9 mm) in which the specified diameters of the run and branch pipes are equal shall be qualified to weld in all positions; on all wall thicknesses, joint designs, and fittings; and on all pipe diameters. A welder who has successfully completed the butt weld and branch weld requirements of 6.3.1 on pipe with an OD less than 12.750 in. (323.9 mm) shall be qualified to weld in all positions; on all wall thicknesses, joint designs, and fittings; and on all pipe ODs less than or equal to the OD used by the welder in the qualification tests. If any of the following essential variables are changed in a welding procedure specification, the welder using the new procedure shall be requalified. a) A change from one welding process to another welding process or combination of processes, as follows: 1) a change from one welding process to a different welding process; or 2) a change in the combination of welding processes, unless the welder has qualified on separate qualification tests, each using the same welding process that is used for the combination of welding processes. b) A change in the direction of welding from vertical uphill to vertical downhill or vice versa. c) A change of filler metal classification from Group 1 or 2 to any other group or from any Group 3 through 9 to Group 1 or 2 (see Table 1). A change of filler metal classification not listed in Table 1 to any other filler metal classification or vice versa. 6.4 Visual Examination For a qualification test weld to meet the requirements for visual examination, the weld shall be free from cracks, inadequate penetration, and BT, and must present a neat workman-like appearance. The depth of undercutting adjacent to the final bead on the outside of the pipe shall not be more than 1/32 in. (0.8 mm) or 12.5 % of the pipe wall thickness, whichever is smaller, and there shall not be more than 2 in. (50 mm) of undercutting in any continuous 12 in. (300 mm) length of weld. When semiautomatic or mechanized welding is used, filler wire protruding into the inside of the pipe shall be kept to a minimum. Failure to meet the requirements of this section shall be adequate cause to eliminate additional testing. 6.5 Destructive Testing 6.5.1 Sampling of Test Butt Welds To test butt welds, samples shall be cut from each test weld. Figure 12 shows the locations from which the specimens are to be removed if the test weld is a complete circumferential weld. If the test weld consists of segments of pipe nipples, an approximately equal number of specimens shall be removed from each segment. The total number of specimens and the tests to which each shall be submitted are shown in Table 3. The specimens shall not include the longitudinal weld. The specimens shall be air cooled to ambient temperature prior to testing. For pipe with an OD less than or equal to 1.315 in. (33.4 mm), one full-pipe section specimen may be substituted for the root bend and nick break specimens. This full-section specimen shall be tested in accordance with 5.6.2.2 and shall meet the requirements of 6.5.3. 30 API STANDARD 1104 6.5.2 Tensile Strength, Nick Break, and Bend Test Procedures for Butt Welds The specimens shall be prepared for tensile strength, nick break, and bend tests, and the tests shall be performed as described in 5.6. However, for the purpose of welder qualification under Section 6, it is not necessary to calculate the tensile strength of the coupons. The tensile strength test may even be omitted; in which case the specimens designated for the tensile test shall be subjected to the nick break test. For qualification of welding equipment and operators under Section 12, the tensile strength test shall not be omitted and the tensile strength shall be determined. 6.5.3 Tensile Strength Test Requirements for Butt Welds For the tensile strength test, if any of the reduced section specimens or the full section specimen breaks in the weld or at the junction of the weld and the parent material and fails to meet the soundness requirements of 5.6.3.3, the welder shall be disqualified. 6.5.4 Nick Break Test Requirements for Butt Welds For the nick break test, if any specimen shows imperfections that exceed those allowed by 5.6.3.3, the welder shall be disqualified. 6.5.5 Bend Test Requirements for Butt Welds For the bend tests, if any specimen shows imperfections that exceed those allowed by 5.6.4.3 or 5.6.5.3, the welder shall be disqualified. Welds in high strength pipe may not bend to the full U shape. These welds shall be considered acceptable if the specimens that crack are broken apart and their exposed surfaces meet the requirements of 5.6.3.3. If one of the bend test specimens fails to meet these requirements and, in the company’s opinion, the imperfection observed is not representative of the weld, the test specimen may be replaced by an additional specimen cut adjacent to the one that failed. The welder shall be disqualified if the additional specimen also shows imperfections that exceed the specified limits. Table 3—Type and Number of Butt Weld Test Specimens per Welder for Welder Qualification Test and Destructive Testing of Production Welds Outside Diameter of Pipe in. mm Number of Specimens Tensile Strength Nick Break Root Bend Face Bend Side Bend Total Wall Thickness ≤ 0.500 in. (12.7 mm) <2.375 <60.3 0 2 2 0 0 4a 2.375 to 4.500 60.3 to 114.3 0 2 2 0 0 4 >4.500 to 12.750 >114.3 to 323.9 2 2 2 0 0 6 >12.750 >323.9 4 4 2 2 0 12 Wall Thickness > 0.500 in. (12.7 mm) ≤4.500 ≤114.3 0 2 0 0 2 4 >4.500 to 12.750 >114.3 to 323.9 2 2 0 0 2 6 >12.750 >323.9 4 4 0 0 4 12 a For pipe less than or equal to 1.315 in. (33.4 mm) in outside diameter, nick break and root bead specimens from two welds or one full-section tensile strength specimen is taken. WELDING OF PIPELINES AND RELATED FACILITIES 31 6.5.6 Sampling of Test Fillet Welds To test fillet welds, specimens shall be cut from each test weld. Figure 10 shows the locations from which the specimens are to be removed if the test weld is a complete circumferential weld. If the test weld consists of segments of pipe nipples, an approximately equal number of specimens shall be removed from each segment. The specimens shall be air cooled to ambient temperature prior to testing. 6.5.7 Test Method and Requirements for Fillet Welds The fillet weld specimens shall be prepared and the test shall be performed as described in 5.8. 6.6 Nondestructive Testing (NDT)—Butt Welds Only 6.6.1 General At the company’s option, the qualification butt weld may be examined by radiography or automatic ultrasonic testing using a qualified NDT procedure in lieu of the tests specified in 6.5. 6.6.2 Inspection Requirements When radiography is utilized, radiographs shall be made of each of the test welds. The welder shall be disqualified if any of the test welds do not meet the requirements of 9.3. When automatic ultrasonic testing is utilized, each test weld shall be fully examined. The welder shall be disqualified if any of the test welds do not meet the requirements of 9.6. Radiographic testing or automatic ultrasonic testing shall not be used for the purpose of locating sound areas or areas that contain imperfections and subsequently making tests of such areas to qualify or disqualify a welder. 6.7 Retesting If, in the mutual opinion of the company and the contractor’s representatives, a welder fails to pass the qualification test because of unavoidable conditions or conditions beyond the welder’s control, the welder may be given a second opportunity to qualify. No further retests shall be given until the welder has submitted proof of subsequent welder training that is acceptable to the company. 6.8 Records A record shall be maintained of the tests given to each welder and of the detailed results of each test. A form similar to that shown in Figure 2 should be used. (This form should be developed to suit the needs of the individual company but must be sufficiently detailed to demonstrate that the qualification test met the requirements of this standard.) A list of qualified welders and the procedures for which they are qualified shall be maintained. A welder may be required to requalify if a question arises about the welder’s competence. 7 Design and Preparation of a Joint for Production Welding 7.1 General Piping shall be welded by qualified welders using qualified procedures. The surfaces to be welded shall be smooth, uniform, and free from laminations, tears, scale, slag, grease, paint, and other deleterious material that might adversely affect the welding. The joint design and spacing between abutting ends shall be in accordance with the welding procedure specification used. 32 API STANDARD 1104 7.2 Alignment The alignment of abutting ends shall minimize the offset between surfaces. For pipe ends of the same specified thickness, the offset should not exceed 1/8 in. (3 mm). Larger variations are permissible provided the variation is caused by variations of the pipe end dimensions within the pipe purchase specification tolerances, and such variations have been distributed essentially uniformly around the circumference of the pipe. Hammering of the pipe to obtain proper lineup should be kept to a minimum. 7.3 Use of Lineup Clamp for Butt Welds Lineup clamps shall be used for butt welds in accordance with the welding procedure specification. When it is permissible to remove the lineup clamp before the root bead is completed, the completed part of the bead shall be in approximately equal segments spaced approximately equally around the circumference of the joint. However, when an internal lineup clamp is used and conditions make it difficult to prevent movement of the pipe or if the weld will be unduly stressed, the root bead shall be completed before clamp tension is released. Root bead segments used in connection with external clamps should be uniformly spaced around the circumference of the pipe and shall have an aggregate length of at least 50 % of the pipe circumference before the clamp is removed. 7.4 Bevel 7.4.1 Mill Bevel All mill bevels on pipe ends shall conform to the joint design used in the welding procedure specification. 7.4.2 Field Bevel Pipe ends should be field beveled by machine tool or machine oxygen cutting. If authorized by the company, manual oxygen cutting may also be used. The beveled ends shall be reasonably smooth and uniform, and dimensions shall be in accordance with the welding procedure specification. 7.5 Weather Conditions Welding shall not be done when the quality of the completed weld would be impaired by the prevailing weather conditions, including but not limited to airborne moisture, blowing sands, or high winds. Windshields may be used when practical. The company shall decide if weather conditions are suitable for welding. 7.6 Clearance When the pipe is welded above ground, the working clearance around the pipe at the weld should not be less than 16 in. (400 mm). When the pipe is welded in a trench, the bell hole shall be large enough to provide the welder or welders with ready access to the joint. 7.7 Cleaning Between Beads Scale and slag shall be removed from each bead and groove. Power tools shall be used when called for in the welding procedure specification; otherwise, cleaning may be performed with either hand or power tools. When semiautomatic or mechanized welding is used, surface porosity clusters, bead starts, and high points shall be removed by grinding before weld metal is deposited over them. When requested by the company, heavy glass deposits shall be removed before weld metal is deposited over them.