基于石墨密封的海底管道维修卡具设计

Design of the graphite sealing based repair clamp for subsea pipelines

海底管道维修卡具是海底管道应急维修的关键设备。通过分析维修卡具的工作原理,确定密封结构尺寸设计是维修卡具设计的关键。采用压缩回弹试验的方式,对轴向石墨密封条的载荷-变形曲线进行了测定,计算出当石墨密封条工程应变达到0.18、氟橡胶密封条工程应变达到0.25时,密封条的工程应力达到3 MPa。通过对密封半环在不同压缩率下的平均接触压力的分析表明,当密封半环径向压缩率达到12.5%时,石墨、氟橡胶密封半环的平均接触压力均超过4 MPa。在确定密封结构尺寸后,通过水压试验对比了石墨和氟橡胶在维修卡具密封应用中的优劣。试验结果表明:石墨可以作为维修卡具的密封材料,在压力等级低于2 MPa的工况中表现良好;在相同的螺栓载荷下,氟橡胶的密封表现优于石墨;石墨材料不会由于老化而导致密封失效,因而基于石墨的海底管道维修卡具有更广阔的应用前景。(图4,表5,参20)

Repair clamp is a key fixture for emergency maintenance of subsea pipelines.In this paper,it was determined by analyzing the working principle of the repair clamp that the key factor to the design of repair clamp is the size design of sealing structure.The load-deformation curve of the axial graphite sealing strip was measured by means of compression rebound test.According to the calculation result,the engineering stress of the sealing strip reaches 3 MPa when the engineering strain of the graphite sealing strip reaches 0.18,or the engineering strain of the fluorine rubber sealing strip reaches 0.25.Then,the average contact pressure of the semi-sealing ring at different compression ratios was analyzed.It is shown that the average contact pressure of graphite semi-sealing ring and that of fluorine rubber semi-sealing ring are both above 4 MPa when their radial compression ratio reaches 12.5%.After the size of the sealing structure was determined,the application advantages and disadvantages of graphite and fluorine rubber to the sealing of repair clamp were compared through hydraulic pressure test.It is indicated that graphite can be used as the sealing material of repair clamp,and it performs well when the pressure is lower than 2 MPa.Under the same bolt load,the sealing performance of fluorine rubber is better than that of graphite.In addition,the sealing of graphite material will not get failed due to aging,so graphite-based subsea pipeline repair clamp is promising in application prospects.(4 Figures,5 Tables,20 References)