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为保证国内0.8设计系数天然气管道试验段高强度试压具有足够的安全裕量,从环向应变与试压压力-容积图曲线非线性偏转量关系、现有标准对试压后管道径向膨胀量的允许值,以及压力逆转现象产生原因3个方面开展研究,提出3项高强度试压合格标准:1为避免管道大范围出现屈服,试压时的压力-容积图曲线非线性偏转量一般情况下不能超过0.2%,特殊情况下不能超过0.4%;2为避免管道局部出现较大塑性变形,试压后管道径向膨胀比例不得超过1.7%;3为进一步增加管道可靠度,可对管道进行无损检测,排除超过临界尺寸的管道缺陷。其中前两项为强制性标准,后一项为推荐性标准。(图3,参6)
In order to ensure that there is enough safety margin for the high-strength pressure test in natural gas pipeline test section with design coefficient of 0.8 in China, from the relationship between hoop strain and non-linear deflection of pressure-volume curve of test pressure test, The allowable value and the reason of the pressure reversal phenomenon are studied in this paper. Three high-strength test standards for pressure test are put forward: 1 In order to avoid yielding over a wide range of pipelines, the nonlinear deflection of the pressure-volume curve during pressure test is normal 2) In order to avoid large plastic deformation in pipelines, the radial expansion ratio of pipes after pressure test shall not exceed 1.7%; 3 In order to further increase the reliability of pipelines, pipelines Perform nondestructive testing to rule out pipe defects that exceed critical dimensions. The first two items are mandatory standards, the latter one is recommended standards. (Figure 3, reference 6)