西三线0．8设计系数试验段管道试压问题

结合西三线0．8设计系数试验段的现场高试验压力要求，系统地对管道试压水平与存留缺陷关系、管道试压下的屈服变形判定条件、累积塑性应变量计算以及压力-容积控制方法中的p—V曲线等进行了分析，结果表明：高试验压力可以显著减少管道存留缺陷；管道试验压力和管材实际屈服强度为影响管道屈服的主要影响因素，试压管节的实际屈服强度若低于93％SYMS，则会发生屈服变形，升压至最高试验压力时，管节的累积塑性应变量与其实际强度有关；管道注满水后的含气率和管道中的低强度钢管对p—V曲线的形状影响较大。

Testing pressure of 0.8 design coefficient pilot section of the 3rd West-to-East Gas Pipeline

For the section of the 3rd West-to-East Gas Pipeline with 0.8 design coefficient, high testing pressure is required on site. In this paper, a system analysis is made on the relationship between testing pressure level and residual defects, judging criteria of yield deformation under the testing pressure, calculation of accumulated plastic strain and p-V curve in the pressure-volume control method. The results show that high testing pressure can help to significantly reduce the residual defects; the testing pressure and actual yield strength are the main factors affecting the yield of the pipeline. If the actual yield strength of testing pipeline section is less than 93% SYMS, yield deformation will occur. When the pressure increases to the max. testing pressure, cumulative plastic strain is connected with its actual intensity. The void fraction of pipe filled with water and the low strength steel pipes have great impact on p-V curve.