Modelling of metal-to-metal seals in a pressure relief valve using advanced FE-analysis
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This study investigates the behaviour of the contact faces in the metal-tometal seal of a typical pressure relief valve.The valve geometry is simplified to an axisymmetric problem.A cylindrical nozzle, which has a valve seat on top, contacts with a disk, which is preloaded by a compressed linear spring.All the components are made of the steel AISI type 316N(L) defined using the multilinear kinematic hardening material model based on monotonic and cyclic tests at 20 • C. Analysis considerations include the effects of the Fluid Pressure Penetration (FPP) across the valve seat which exists at two different scales.There is certain limited fluid leakage through the valve seat at operational pressures, which is caused by the fluid penetrating into surface asperities at the microscale.At the macroscale, non-linear FEanalysis using the FPP technique available in ANSYS revealed that there is also a limited amount of fluid penetrating into gap.Accurate prediction of the fluid pressure profile over the valve seat is addressed in this study by considering the FPP interaction on both scales.The shape of this pressure profile introduces an additional component of the spring force, which needs to be considered to provide a reliable sealing.The analysis showed that the evolution of the profile, which is caused by the isotropic softening of the material, is significant during the cyclic operation of the valve.Keywords:
Valve seat
Microscale chemistry
Relief valve
This paper presents an experimental investigation on the sealing defects and cracks of O-rings and a valve packing of a gas valve for a LPG cylinder. O-ring in which stops a gas leakage of a liquefied petroleum gas is very important for a LPG valve safety. Valve packing is to open and close a gas flow port for supplying and charging a LPG fuel. The sealing performance of two sealing units ism related to the leak safety and long lift of a gas valve. The investigated results show that most of O-rings was failed due to a circumferential crack in which is caused by partial press bonding failure near the partition zone and an excess compression rate. Some of the O-ring failure was originated by an extrusion of an excessive leak pressure of a LP gas. Thus, this paper strongly recommends a tight quality control and a safety guarantee system of O-rings and valve packing to guarantee a leak safety and to extend a service lift of a gas valve. At the end, a warranty policy of the sealing units should be adopted for increasing a product quality and safety of a gas valve.
Liquefied petroleum gas
Safety valve
Relief valve
Valve seat
Control valves
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In this paper, the FEM result has been presented for a sealing safety between a valve packing and a valve seat during a open and close operation in a LPG cylinder. The sealing operation of a LPG valve is completed when the valve packing in which is made by a nylon-66 polymer is to stop a LP gas flow, which flows out from the outlet of a brass pipe in a LPG cylinder. The contact sealing mechanism of the valve may be classified by a flat contact of an unused valve packing and a circular groove contact of an used valve packing in a current LPG valve. Based on the FEM and experimental investigations the sealing force, 4.9 MPa for a flat contact mode of the unused valve packing is a little high compared to that of the used valve packing, which shows a circular groove contact geometry against a valve seat. But these sealing pressures for two contact modes are very low compared to the ultimate strenath 83 MPa of the nylon-66 and this may be designed with a excess strength of the valve.
Valve seat
Groove (engineering)
Brass
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For the exhaust valve-valve seat wear of CNG engine,the geometry dimension,microstructure and stiffness of exhaust valve-valve seat were detected and analyzed by the way of macro examination,geometry measurement and chemical component analysis.In addition,the wear state of exhaust valve-valve seat was studied.The results show that the engine fuel,exhaust valve-valve seat material match and valve train system structure are the main factors influencing exhaust valve-valve seat wear.In the end,the measures of improving the exhaust valve-valve seat wear are put forward and verified.
Valve seat
Valve timing
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A globe valve used usually under the high pressure condition is easy to make a fluid leak for structural problem despite precise process. In this paper, a designed valve having a groove at the inside of seat decreases deformation toward outside through structural bending. Hence, it will be helpful on anti-leakage of valve. With finite element method, in order to confirm anti-leakage of a valve the effect of process parameters on the deformation was performed by optimal design of experiment. Furthermore, the suggested valve figured out about its efficiency comparing with common seat.
Valve seat
Leakage (economics)
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An illustrative embodiment of the invention provides pressure relief valve means for the core support cylinder of a nuclear reactor vessel during a failure or accident of the nuclear reactor system. The valve means is responsive to differential pressure across the valve which in one direction sealably seats the valve plate against the valve body, and which, in the other direction opens the valve for pressure relief of the cylinder. Moreover, the valve means is provided with energy absorbing means which limit the impact load of an ''explosively'' opening valve on the reactor vessel wall. 6 claims, 4 figures.
Relief valve
Differential pressure
Valve seat
Safety valve
Needle valve
Gate valve
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According to the investigation about valve seat of fluid end of F-1300 mud pump in field usage,approximately 80% valve seats were destroyed ahead of its design life and needed to be replaced frequently.In order to discover this failure,a contact analysis has been developed to study the interactions between valve seat,valve body and hydraulic cylinder with the FEA software in the paper.At the same time the causation of destroyed valve seat and reviewed the distribution of the stress and the strain of the valve seat was discussed.Several advices about improving the life-span of valve seat are put forward.
Valve seat
Check valve
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This device enables pressure‐relief, pressure‐regulating, and other hydraulically operated diaphragm globe valves to be calibrated, diagnosed, and operated with a hydraulic hand pump. The pump, used in conjunction with a pressure gauge, takes the guesswork out of determining which pressures are needed to open, regulate, and close a valve. It is especially valuable because it allows the tester to know exactly at which pressure the main valve will open, regulate, or close, without waiting for an actual high‐pressure situation.
Relief valve
Hydraulic pressure
Diaphragm (acoustics)
Pressure regulator
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Valve seat
Relief valve
Microscale chemistry
Cabin pressurization
Fluid pressure
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The prefered valve types to reduce back pressure are the pilot operated valve, the balanced direct spring valve, and the conventional direct spring valve. Back pressure (static pressure at the outlet when the valve is closed), superimposed back pressure, and built up back pressure are defined. The relief characteristics of the pilot, balanced, and direct spring valves are schematicized. Typical safety valve operations are outlined. Methods for sizing discharge piping to avoid piping pressure losses that produce excessive back pressure are recommended. The guidelines discussed improve overpressure protection.
Relief valve
Safety valve
Overpressure
Back pressure
Check valve
Control valves
Valve actuator
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Simple design change for poppet relief valve enables flow through valve to exert additional force to help keep valve open. Although originally intended for relief valves for liquid oxygen and liquid nitrogen in Space Shuttle orbiter, concept is applicable to pressure-or flow-actuated valves for wide range of fluids and temperatures.
Relief valve
Valve seat
Orbiter
Liquid flow
Valve actuator
Needle valve
Safety valve
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