Performance Research And Improvement Design Of 140MPa High Pressure Manifold

High-pressure manifolds play an important role in oil industry equipment and are widely used in oilfield drilling,cementing,logging,fracturing operations,oil testing operations,coiled tubing operations,sand control operations and offshore platforms.As the difficulty of fracturing operations increases,the pressure level of the manifold increases continuously,reaching 140 MPa.In the part where the fluid velocity and flow direction are changed,the bursting is most likely to occur,mainly due to the failure of the movable elbow,the tee,the plug valve and the like,which causes the manifold to fail and burst,which seriously threatens the safety of the sand fracturing construction personnel and equipment.In this paper,the high-pressure movable elbow is studied,and the failure analysis,erosion wear,heat treatment process,fatigue life and structural improvement are studied.According to the summary of the manifold failure samples and related literatures at home and abroad,it is concluded that the lack of life of the high-pressure manifold is mainly caused by the material properties of the manifold and the external erosion.For the external erosion effect,the flow conditions in the elbow structure are studied for the main factors such as fluid velocity,particle diameter,mass flow rate and fluid viscosity.The influence of different factors on the erosion rate is obtained,and the erosion rate of each factor is analyzed influence level.In terms of material properties,the heat treatment process of high-pressure movable elbow was studied.15 CrNiMo steel was selected as the research object,and 15 CrNiMo steel was used in several different heat treatment processes(such as carburizing,water quenching,austempering,low temperature tempering).Etc.),comparative analysis of metallographic structure,hardness,wear resistance after each heat treatment process.It is found that 15 CrNiMo steel is treated by carburizing + austempering.The final working surface can obtain lower bainite structure,and its strength and wear resistance are significantly improved.The core material still has good plasticity and toughness,which can improve the material.Comprehensive mechanical properties to extend the service life of high-pressure movable elbows.The different mechanical methods for studying fatigue life are analyzed.Finally,the theory of fracture mechanics is used to theoretically calculate the life of high-pressure movable elbows under different stress amplitudes,which provides a reference for pipeline maintenance personnel to make inspection cycles.In the study of elbow erosion wear,we have obtained the most wearable position of the elbow at the inner wall of the outer arc.Therefore,the above-mentioned conclusion can be made to improve the wall thickness of the elbow structure.In the case where the inner wall thickness is satisfied,the outer wall thickness is appropriately increased to increase the service life.