centers on key welding engineering considerations encountered in the Procedure Qualification Record (PQR) process to support oil/gas project initiatives. Projects In Alaska, welding engineering plays a crucial role in the fabrication, maintenance, repair/refurbishment, and alteration of 1) the 800-mile-long Trans-Alaskan Pipeline System (TAPS); 2) oil/gas production facility machinery and pipework; 3) oilfield well equipment such as casings, Bradenheads, and a countless array of valves and fittings that require hardfacing or cladding; 4) seawater piping systems; 5) drill site and flowstation equipment and pipework; 6) waterway pipe crossings, vehicle bridges, storage tanks, and vessels; 7) equipment platforms, building frames, and myriad horizontal/vertical pipe support mounts; and 8) natural gas pipeline and pipework systems. In addition, for each respective welding activity, there is a corresponding need for weld inspection. Consequently, the performance of visual weld inspection by AWS Senior Certified Welding Inspectors and Certified Welding Inspectors, and the utilization of nondestructive examination (NDE) technologies, including radiography, ultrasound, magnetic particle, penetrant, and leak testing by ASNT NDT Level II/III personnel is required. PQR Process Procedure qualification records (PQRs) utilized for project structural applications and in the construction of pipework and pipelines must demonstrate that the welding process proposed is capable of producing a weld joint that will meet the specified service design and performance requirements of the weldment. For Alaskan and Arctic service applications, importance is placed on the diligence and integrity of the PQR process and in the accuracy of the PQR document. The criticality of developing a comprehensive PQR is to ensure 1) the reproducibility of PQR weld variables throughout production welding; that is, based upon the recording of actual weld variables employed during the PQR process to achieve a compliant weld joint, a detailed WPS may be written to provide direction throughout production welding; 2) the weld joint meets specified/ intended service design and performance requirements by conducting rigorous NDE inspection and chemical analysis as well as mechanical, metallurgical, and environmental testing to ASTM G48 (Ref. 1) and A262 (Ref. 2). The following welding engineering considerations encountered in the PQR process are key. Fracture Toughness Testing Where the majority of weldment materials are carbon and low-alloy steels, during procedure qualification, meeting weld/base metal fracture toughness requirements specified by an engineering authority is critical. Outdoor welds/weldments are subjected to bitter Arctic cold and frigid Alaskan winters on a prolonged basis, as well as to potential seismic activity — Fig. 3. Therefore, depending upon the piping or structural application, Charpy V-Notch (CVN) fracture toughness impact testing is conducted in accordance with ASME Boiler and Pressure Vessel Code Section IX, API Standard 1104, or AWS Codes. For a project, an engineering authority will outline the CVN test and acceptance criteria such as the specimen test temperature (e.g., –50˚F/ –46˚C), and the minimum impact energy in ft-lb/Joules that specimens must endure. In addition to CVN testing, the crack tip opening displacement (CTOD) test may be utilized to evaluate fracture toughness. Pipeline girth weld CTOD testing is performed in accordance with API Standard 1104. An engineering authority will specify minimum acceptance criteria. However, unlike the CVN test, the CTOD test JUNE 2016 / WELDING JOURNAL 73 Fig. 2 — Remote project work at the Kuparuk River and Prudhoe Bay oilfields utilizing SMAW.
Welding Journal | June 2016
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