液压拉伸法紧固法兰螺栓的载荷损失研究

Research on Load Loss of Tightening Flange Bolts by Method of Hydraulic Tensile

法兰连接系统被广泛应用于航天、石油、化工等相关领域,法兰发生泄漏会造成严重的危害,故法兰螺栓的紧固工作显得尤为重要。工程中常用液压拉伸法来紧固管法兰螺栓,鲜有学者对液压拉伸紧固法兰螺栓的螺栓载荷损失情况展开研究。在研究螺栓载荷损失情况时,首先进行螺栓材料的力学性能测试试验来测试螺栓材料的弹性模量、屈服强度等力学性能参数,为拉伸紧固试验提供理论计算;然后按照ASME PCC-1中对螺栓分步拉伸紧固的方法,采用3种不同的拉伸应力且每种拉伸应力下均运用四步加压法对其进行紧固;最后根据螺栓剩余载荷和拉伸力的关系可以得出螺栓载荷损失的情况。结果表明,35CrMo的M27螺栓的温度越高,其弹性模量和屈服强度越低;拉伸紧固螺栓时,螺栓所受拉伸载荷越大,则螺栓载荷的损失率也越大。

Flange connection system was widely used in aerospace,petroleum,chemical industry and other related fields,flange leakage would cause serious harm,so the tightening of flange bolts was also particularly important.The hydraulic tensile method was commonly used in engineering to tighten the pipe flange bolts,and few scholars have studied the loss of bolt load of hydraulic stretching flange bolts.When studying the bolt load loss,firstly,we did the mechanical properties test of the bolt material to test the elastic modulus,yield strength and other mechanical property parameters of the bolt material,which provided theoretical calculations for the tensile tightening test.Then,based on the step-by-step tensile tightening of the bolt in ASME PCC-1,three different tensile stresses were used and the four-step compression method was used to tighten it under each tensile stress of the four.Finally the bolt load loss could be obtained according to the relationship between the residual load of the bolt and the tensile force.The results showed that the higher the temperature of the M27 bolt of 35CrMo was,the lower its elastic modulus and yield strength were.When stretching and tightening a bolt,the greater the tensile load on the bolt was,the greater the loss rate of the bolt load was.