Research On Flange Metal Sealing Monitoring Techniques Of Well Control Device Based On Stress-magnetization

As the main seal form of wellhead equipment in high pressure oil gas well.Flange metal seal was influenced by the size and distribution of bolt pre-tightening force?the variation of the temperature and pressure and material of the sealing steel-ring,which was prone to cause sealing failure of flange connection,the leakage of high pressure fluid,result in the waste of energy and materials,environmental pollution,even casualties ? property loss and other serious hazards.Therefore,the research and development of flange metal seal condition supervising soft-hardware system for well control devices was of great significance for early detection of leakage caused by flange metal seal failure.In view of the shortcomings of existing flange metal seal monitoring technology,the research work has been carried out as follows:(1)By summarizing and comparing the domestic and foreign flange metal seal detection methods,the related experimental schemes were put forward,which were about the monitoring technology of flange metal seal based on magneto-mechanical coupling,included two parts of bolt stress state testing experiment and flanged metal seal monitoring experiment.The experimental equipment and related experimental parameters were introduced in detail.(2)The experiment program was simulated by ANSYS software.The metal sealing model of flange was established by APDL programming.The influence of different working conditions of flange(pre-tightening and operation)and different stress states of flange connection bolts on the stress distribution of the flange?bolts and steel ring were analyzed.A quantitative mechanical model was established between bolt stress and the stress distribution of the steel ring(flange metal sealing),which provided theoretical basis for evaluating flange metal sealing performance by detecting bolt stress.(3)The relevant research was carried out according to the experimental schemes.The quantitative relationships between 35 CrMo bolt stress and magnetic signal under different load conditions(loading and unloading)were established by bolt stress state test,bolted magnetic signal was in direct proportion to stress in a certain range.Then,through flange metal seal monitoring experiments,it was verified that flange metal sealing could be judged by detecting the magnetic signals of bolts,the flange metal sealing is affected by the number of unpretightened bolts?the distribution of the bolts stress and internal pressure.(4)The quantitative relationship between magnetic signal and flange sealing was obtained by combining the simulation and experimental results.Then the monitoring software of flange metal sealing based on force and magnetic coupling was developed to realize the data processing of magnetic signal,simulation calculation of stress distribution in each part of flange system,the evaluation and monitoring of the flange metal seal were achieved.The software provided support for field application.