The calculation and determination of the axial force of the EHV globe valve under different seal types are expounded and demonstrated. The influence of the sealing mechanism of the EHV globe valve and the machining accuracy of the seal face on the axial force of the globe valve and the influence of the sealing material Use. 1, an overview of high-pressure valve sealing material is usually metal to metal, in order to close the shut-off valve sealed tightly, you must improve the sealing surface of the machining accuracy and roughness levels, and the sealing surface to exert a very large axial sealing force. However, the axial sealing force is not as large as possible. There is a view that the ultra-high pressure globe valve (≥ 300MPa) should be sealed plastic method, and most of the use of tapered linear seal. The so-called plastic seal, is the sealing surface seal pressure equal to the yield pressure of the soft sealing material side, so that the bonding surface in close contact with the use of plastic materials and soft plastic block the uneven surface of the hardware to form an approximate ideal plane and produce equal to the soft Material yield limit of the reaction and keep the seal. 2, axial force analysis Stem axial force mainly depends on the total force of the sealing surface, the valve seal to determine the design of the total force of the key parameters is the seal than the pressure. However, in the case of cone-line sealing of an EHV globe valve, whether the q value of the seal pressure q produced by the axial force Q in the absence of the medium pressure can be greater than the yield limit δs of the soft material in the sealing sub-assembly can be increased. When the medium pressure is OFF Of the seal than the pressure q is equal to δs, this article will discuss the appropriate value of q. 3, the sealing surface roughness on the axial force According to only when the gap between the sealing surface is smaller than the diameter of the media molecules in order to ensure that the medium does not see leakage, it can be considered, to prevent fluid leakage gap value must be as small as 0.003μm . However, even after lapping, the height of the convex surface on the metal surface still exceeds 0.05 μm. To achieve the ideal plane, it is necessary to exert a certain force on the contact surface. The magnitude of this force is proportional to the σs of the sealing soft material and the roughness of the sealing surface Degree related. When the sealing surface of the specific pressure q <40MPa, the quality of the sealing surface plays a decisive role. For example, at q = 65MPa, as the roughness level becomes higher and higher, the amount of permeation decreases rapidly, that is to say, at q <40MPa, the higher the degree of roughness is, Small, the smaller its axial force. However, for σs> 900MPa sealing sub-material, when used for 300MPa super high pressure valve, considering the linear elastic fracture mechanics, [σ] should be considered from the strength requirement, Ra0.05μm or more, but also from the sealing mechanism. Therefore, for the σs of 900MPa high pressure valve seal, the sealing surface roughness must Ra0.05μm or more. For HIP treated WC cemented carbide seals, due to its relatively brittle nature, to increase the pressure on the sealing surface to compress the sealing surface of the peak, it will increase the axial force, and will So that the sealing pair is broken. (In the case of Fisher's valve, there is an example of valve seat fracture due to improper adjustment of axial force.) Therefore, the roughness of the sealing surface must be higher than Ra0105μm. Only in this range can we use the equation (13) for calculating the axial force. 4 Conclusion EHV closing valve sealing mechanism points in the narrow elastic plastic seal and wire seal two types. As the valve seat (or flap) plastic deformation of the sealing surface after cold hardening phenomenon, so the increase of axial force and the seat sealing surface width is not proportional to the increase. The diameter of 1 / 2in. (15mm) above the sealing material of high pressure valve to HIP treatment of WC carbide is appropriate, the sealing surface must have a high degree of roughness, while the axial force formula has a certain range of use . More keyword search: Globe valve
Boom Lift Mini Power Pack
Hydraulic Power Unit,Mini Portable Power Pack,Mini Power Pack For Boom Lift,Boom Lift Mini Power Pack
GRH , https://www.grhcn.net