In this investigation, the mechanical properties and low-temperature fracture toughness of API 5L X65 offshore pipeline welded joints were studied. Structure Integrity Assessment Procedure (SINTAP)—Failure Assessment...In this investigation, the mechanical properties and low-temperature fracture toughness of API 5L X65 offshore pipeline welded joints were studied. Structure Integrity Assessment Procedure (SINTAP)—Failure Assessment Diagram (FAD) method was applied to the pipe structure with surface flaw at the weld toe. According to the ISO standard BS7448, the CTOD fracture toughness of the welded joints was determined at the temperature of 0℃. For the heat-affected zone (HAZ) specimens, post-test metallographic analysis was performed to verify that the tip of the crack was located in the coarse crystal zone in order to confirm the validity of the above results. The failure lines of analysis level 1 and 3 of weld metal were derived from the results of the mechanical property test. The assessment was performed, considering the maximum lay stress, residual stress conservatively assumed to be uniform tensile stress, and minimum CTOD value. The results of the assessment showed that pipeline structure with a surface flaw (the height and length are respectively 2.2mm and 5mm) at the weld toe is safe. This study lays the foundation of application of SINTAP to pipeline structure assessment.展开更多
To meet the demands of rapid development of pipeline constructions in China, a complete set of full automatic external welding machine for annular welds of pipeline and welding procedure have been developed thereof. T...To meet the demands of rapid development of pipeline constructions in China, a complete set of full automatic external welding machine for annular welds of pipeline and welding procedure have been developed thereof. The system has been applied in the “West East Pipeline Project” and its performance is proven. With this welding machine the welding parameters can be either preset before or adjusted in real time during the welding process, which avoids the blemishes of same type domestic and international products. Thus it is best propitious to in situ construction conditions and workers’ technical level in China. In this article the development of mechanical and control systems of this product is introduced and typical welding procedure parameters are provided.展开更多
文摘In this investigation, the mechanical properties and low-temperature fracture toughness of API 5L X65 offshore pipeline welded joints were studied. Structure Integrity Assessment Procedure (SINTAP)—Failure Assessment Diagram (FAD) method was applied to the pipe structure with surface flaw at the weld toe. According to the ISO standard BS7448, the CTOD fracture toughness of the welded joints was determined at the temperature of 0℃. For the heat-affected zone (HAZ) specimens, post-test metallographic analysis was performed to verify that the tip of the crack was located in the coarse crystal zone in order to confirm the validity of the above results. The failure lines of analysis level 1 and 3 of weld metal were derived from the results of the mechanical property test. The assessment was performed, considering the maximum lay stress, residual stress conservatively assumed to be uniform tensile stress, and minimum CTOD value. The results of the assessment showed that pipeline structure with a surface flaw (the height and length are respectively 2.2mm and 5mm) at the weld toe is safe. This study lays the foundation of application of SINTAP to pipeline structure assessment.
文摘To meet the demands of rapid development of pipeline constructions in China, a complete set of full automatic external welding machine for annular welds of pipeline and welding procedure have been developed thereof. The system has been applied in the “West East Pipeline Project” and its performance is proven. With this welding machine the welding parameters can be either preset before or adjusted in real time during the welding process, which avoids the blemishes of same type domestic and international products. Thus it is best propitious to in situ construction conditions and workers’ technical level in China. In this article the development of mechanical and control systems of this product is introduced and typical welding procedure parameters are provided.
