压力平衡式旋塞阀结构特点及内漏处理方法

西气东输管道干线截断阀的旁通管道节流阀、放空阀,站场ESD放空管道放空阀,大量使用进口Serck Audco压力平衡式旋塞阀。针对站场ESD高压放空旋塞阀内漏故障频繁,常规处理效果不好的问题,分析了进口旋塞阀的密封及压力平衡结构特点,结合现场实践经验提出了注脂处理、解体维修、更换阀门、返厂维修等处理方法。旋塞阀频繁内漏的根本原因是旋塞表面本体磨损、划伤,导致密封失效。现场解体维修中,旋塞和阀体之间的间隙难以保证恢复至原始状态,旋塞经人工打磨很难达到原始匹配精度,多次解体后维修效果可能会更差,因此解体维修应谨慎开展。返厂维修消除了旋塞表面磨损、划伤,经现场试验验证可以解决阀门内漏问题,但国产旋塞阀及国内厂家维修后的进口旋塞阀均需增加旋塞大端泄压孔,才能消除旋塞自锁现象。大端泄压孔与介质流体直接接触,当阀门用于管道介质含杂质较多的工况时,不能避免杂质进入大端底部,旋塞阀的国产化研制应在这方面开展研究。(图4,参16)

Structural characteristics of pressure balanced plug valve and treatment methods for internal leakage

Most of the imported Serck Audco pressure balanced plug valves are adopted for the bypass throttle valves,vent valves and station ESD vent valves of the block valve on the trunk line of PetroChina West-to-East Gas Pipeline.Internal leakage faults of plug valves for station ESD high-pressure venting occur frequently,but the conventional treatment appears not to be satisfactory.Through the analysis on structural characteristics of sealing and pressure balance of the imported plug valves,treatment methods such as grease filling,disassembly for maintenance,valve replacement,and return for repair were put forward based on field practical experience.The root causes of frequent internal leakage of plug valve attribute to abrasion and scratch on surface of plug valve body that may result in sealing failure.During field disassembly and maintenance,the clearance between the plug and the valve body was hard to be restored to its original state.It is hardly possible to reach the original fit accuracy after manual grinding,and the repair effect may be worse after several times of disassembly.So the disassembly and maintenance should be treated with caution.Return for repair might be able to eliminate the abrasion and scratch on the plug surface,and the internal leakage problem of the valve was verified by the site test and proved to be solvable.But for domestic plug valves or imported plug valves repaired by domestic manufacturers,the additional pressure relief nozzle at the large end of the plug is required to eliminate the plug self-locking phenomenon.The pressure relief nozzle at the large end is in direct contact with the medium fluid,and impurities cannot be prevented from entering the bottom of the large end under the working condition that the valve is used for pipeline medium containing large amounts of impurities.Research should be carried out in these aspects for the localization development of plug valves.(4 Figures,16 References)