管道钢级提高对B31G标准适用性的影响

Impacts of pipeline steel upgrading on applicability of B31G standards

为了研究油气管道钢级普遍提高对B31G标准的影响规律,从屈强比、流变应力和缺陷深度比等因素出发,系统地分析了管线钢屈强比变化对流变应力取值的影响,并在对不同版本的B31G标准进行对比的基础上,详细分析了缺陷深度比变化与管道钢级提高所造成的B31G标准计算结果保守性和集中性的变化。研究结果表明:随着管道钢级提高,B31G标准计算结果的保守性逐渐减小,并向冒进发展,计算结果的集中性也明显变差,由此导致了B31G标准对高钢级管道适用性越来越差,通过对流变应力取值重新定义能在一定程度上改善B31G计算结果的保守性,但难以从根本上解决集中性差导致的适用性问题。

To determine impacts of extensive upgrading of pipeline steel to applicability of B31 G standards, yield-tensile ratio, fl ow stress, defect depth ratio and other factors are studied systematically to highlight impacts of changes in yieldtensile ratio of the pipeline to value of fl ow stress. In addition, different editions of B31 G standards are reviewed to clarify changes in conservative properties and centrality of calculation results obtained by using B31 G standards induced by changes of defect depth ratio and upgrading of pipeline steel. The research results show that, with the increase of pipeline steel grades, the B31 G calculation results become gradually less conservative, and tend to be aggressive. Moreover, the calculation results are much less centralized. In this circumstance, the B31 G standards become less and less applicable to high-grade steel pipes. By redefi ning the value of fl ow stress, conservative properties of B31 G calculation results can be enhanced to a certain extent, but it is diffi cult to fundamentally solve the problems related to applicability induced by low centrality.