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焊接质量控制是油气管道安全运营的重要保障。对于高强钢管道,焊接缺陷的尺寸控制是当前管道施工中的瓶颈问题。在管道对接焊这一关键施工环节中,环焊缝气孔缺陷的形成实难避免。为了研究其尺寸控制指标的适用性,根据实际管道环焊缝的坡口形状和热影响区材料的软化现象,建立了非线性有限元分析模型。以管道设计标准为依据,确定了管道环焊缝应力分析的极端载荷条件,并采用基于流动应力的失效判据,对含气孔缺陷的管道环焊缝进行了应力分析。结果表明,不同径向位置气孔的管道环焊缝应力水平相当,X90钢级管道对环焊缝气孔缺陷的容限能力低于X80钢级管道,现行标准中关于气孔缺陷的3mm尺寸控制指标适用于X80和X90钢级环焊缝管道。
Welding quality control is an important guarantee for the safe operation of oil and gas pipelines. For high strength steel pipe, the size control of welding defects is the bottleneck in the current pipeline construction. Butt welding in the pipeline construction of this key link, the formation of girth weld defects is hard to avoid. In order to study the applicability of its dimensional control index, a nonlinear finite element model was established based on the groove shape of the actual girth weld and the softening of the material in the HAZ. Based on the pipeline design criteria, the extreme loading conditions of the stress analysis of the pipe girth weld were determined, and the stress analysis of the pipe girth weld with porosity defects was carried out by using the failure criterion based on the flow stress. The results show that the stress level of the pipe girth weld in different radial position stomatal is quite equivalent. The tolerance of X90 steel pipe to the girth defects of girth weld is lower than that of X80 steel grade pipe. The 3mm size control index for stomatal defects in current standards is applicable X80 and X90 in the level of girth pipe.