载荷作用下整体式绝缘接头密封性能研究

The sealing performance research of integral insulating joint under loading

整体式绝缘接头是油气管道的薄弱环节,因密封失效而导致油气泄漏是绝缘接头的主要失效形式。通过ABAQUS软件建立整体式绝缘接头的有限元模型。采用热膨胀法施加预紧力,对比分析了整体式绝缘接头在不同轴向拉力和外弯矩作用下的密封可靠性。通过分析得出:弯矩作用下,绝缘接头一侧受拉,另一侧受压。在受压侧,绝缘垫板受到左右法兰的挤压作用,产生明显的应力集中。在受拉侧,绝缘接头的失效形式与轴向拉力作用下的失效形式基本相同,即最大应力首先在勾圈中间部位达到屈服极限,随变形量的增加,左右法兰端面形成间隙,从而引起密封圈压缩量减小,最终导致油气泄漏。

Integral insulating joint is the weak link of oil and gas pipelines, its main failure mode can be reflected by the oil and gas leakage due to the sealing failure. Using the thermal expansion method to realize the pretension, the sealing reliability of the inte-gral insulating joint under different axial tension and external bending moment was compared and analyzed by finite element meth-od modeling with ABAQUS software. The results show that under bending load, one side of the insulation joint is pulled and the other side is pressed. At the compression side, significant stress concentration is created in the insulating pad due to the extrusion of the left and right flanges. At the tension side, the failure mode is similar with that under axial tension： the maximum stress first reaches the yield limit in the middle of the hook ring; and with the increase of the deformation, the gap is formed between the end faces of the left and right flanges, which will decrease the compression volume of the seal ring and eventually lead to oil and gas leakage.