Study On Prolonging Life Of Ultra High Pressure Relief Valve

Ultra high pressure is a new technology using pressure over 100MPa to process material, which is achieved purpose of people. Now days, it is already extensive applied in making super hard materials, chemistry industry, petroleum chemical engineering, processing technology, equal static pressure processing, ultra high static pressure processing, fine powders metallurgy, metals shaping and the Earth physics, the geology mechanics research etc.realm. The ultra high pressure relief valve is the important part of the ultra high pressure system, the credibility and service lives that it works affect the safety and the work efficiency of the system directly. It must have function to bear high pressure, heat, impact and wear ect. Under the 300 MPa above high pressure, the service life of the existing relief valves is more than ten times at best and only 2-3 times at worst, even only once. Ultra high pressure relief valves become "bottle nech"problem badly to prevent the progress of ultra high pressure Firstly this research investigates the ultra high pressure relief valves. Sum up the main failure form of the ultra high pressure relief valves, that is the breaking and smashing of the needle valves, sealing face appearing the plough ditch, small pit, sealing rings and its nearby burn。There are also analyses about the reasons of these forms and the factors influencing the extra ultra high-pressure relief valves. According as degree of influence, ratio of function and price and experiment condition,carry on special research in four factors influencing ultra high pressure relief valves life, that is material, hardness, sealing surface roughness and the impingement angles,here also get a conclusion that: The influence of the material category to the valve plug life span is very big; The influence of the degree of hardness to the valve plug life span is big, with the exaltation of the material degree of hardness, the valve plug life span also has the significant exaltation; The influence of Sealing face roughness to the valve plug life span is not big within the scopes of Ra1.6-0.4μm, but total trend is the sealing face roughness is more low, the life span is more long, roughness Ra≥1.6μm, will lower the service life of the valve plug consumedly. The influence to the valve plug life span of the sealing face with the conicity in 40°～60°is not big. Put forward myself new views: 1, heightening ultra high pressure relief needle valves'processing accuracy and surfaces roughness, guaranteeing Ra ≤0.8 μm; 2, Hardness influence life, but is not the absolute factor, under same degree of hardness, the material that has the anti-skiving ability and red rigidities can prolong the life span of the valve plug; 4, Choosing right sealing press ratio, using the wrench to carry on the lock tightly, or carrying out the automation control of the valve, can avoid the needle valve hurt; 5, adding cooling off device at relief valve to avoid the valve working under high temperature. Apply ultra high pressure valve plug made with optimized parameters to the 800 MPas-15L ultra high pressure experiment in our school, and the valve had worked well 60 times under 700 MPa, that is to say the life span raises over 10 times compared with past.