Research on Strain of Unequal Wall Thickness Pipeline of the X80 Pipeline under Lateral Load

Abstract

X80 steel is a material with high strength and good toughness, which is widely used in long-distance natural gas pipelines. Pipelines will have different wall thicknesses, depending on the safety level requirements of different regions. Two sections of pipes with different wall thickness form unequal wall thickness of pipeline (UWTP) that is joined together by welding. UWTP pass through some geohazard areas, such as landslides. The frequency of landslides is extremely high in mountainous areas, which can seriously affect the safe operation of UWTP. In this paper, a model of a 12.8 mm wall pipe section and a 15.6 mm wall pipe section are linked by girth welds. The strain between the pipe section and the weld was quantitatively analyzed. The results show that the strain at the girth weld in the 3 o’clock direction of the pipe increases sharply. The strain in the 9 o’clock direction of the pipe is generally lower than the strain in the 3 o’clock direction. The strain value of the 12.8mm wall thickness pipe section is generally greater than the strain value of the 15.6mm wall thickness pipe section.