含环向表面裂纹管道的试验研究及安全评定

Experiment Investigation and Safety Assessment on Pipes with Circumferential Surface Crack

油气管道承受内压载荷和地质沉降导致的弯矩载荷的双重作用。为形成一套试验和标准相结合的较完整的安全评定体系,以某X42管线钢制含环向表面裂纹的管道为研究对象,通过BS7910:2005标准计算管道的容许载荷与对应弯矩,结合内压—弯矩加载试验分析评定结果的保守度,进而计算不同内压—弯矩组合载荷下各评定点的安全裕量。根据BS7910:2005标准,提出了管道1A级和2A级评定结果的保守度分别为51.7%和32.2%;弯矩是导致含环向表面裂纹管道失效的主要原因,在没有弯矩载荷作用的前提下,确定了管道在13 MPa设计压力下的1A级和2A级评定安全裕量分别高达60%和68%。

The oil/gas pipeline is subjected to the dual effect of the internal pressure load and the geological sedimentation caused bending moment load. To form a set of complete safety assessment system combining the test and the standard, X42 pipeline steel made pipe with circumferential surface crack is taken as the research object. Its permissible load and corresponding bending moment are calculated using the BS7910：2005 standard. Through analysis on the conservative degrees of assessment results by introducing the loading test of internal pressure and bending moment, safety margin of each assessment point under different combined loads of internal pressure and bending moment is calculated. The suggested conservative degrees of assessment results are 51.7% and 32.2% respectively under the 1 A grade and 2 A grade as per the BS7910：2005 standard. The bending moment is the main cause of the failure for the pipe with the circumferential surface crack, and under the premise of no bending load and the design pressure of 13 MPa, it is determined that the safety margins of the pipe under 1 A grade and 2 A grade assessment are 60% and 68%, respectively.