Factors Affecting the Sealing Performance of Globe Control Valves

Aug. 02, 2021

Globe control valves have been widely used in general industrial pipelines and liquid oxygen and liquid hydrogen transportation pipelines in the nuclear and aerospace industries due to their low sealing resistance, rapid and convenient switching, long life, good sealing, and high reliability. With the continuous increase in the amount of globe control valves and the stricter operating conditions, the sealing performance of the globe control valve has become extremely important. The following will discuss several factors that affect the sealing performance of the globe control valve.

LN81 Series Single Seat Globe Control Valve

LN81 Series Single Seat Globe Control Valve

Specific Pressure on the Sealing Surface

Specific pressure is the pressure acting on a unit area of the sealing surface. The specific pressure is caused by the pressure difference between the front and rear of the valve and the outer cover. The specific pressure directly affects the sealing performance, reliability and service life of the globe control valve.

The Physical Properties of the Fluid

LN83 Series Cage Guided Globe Control Valve

LN83 Series Cage Guided Globe Control Valve

The Influence of Viscosity

The permeability of a sealing fluid is closely related to its viscosity. Under the same conditions, the greater the viscosity of the fluid, the lower its permeability.

The Influence of Temperature

The permeability of a fluid depends on the temperature that causes the viscosity to change.

The viscosity of the gas increases with the increase in temperature, and it is proportional to the square root of the temperature of the gas. The viscosity of the liquid is on the contrary, it decreases sharply as the temperature rises, and it is inversely proportional to the cube of the temperature.

In addition, changes in the size of parts caused by temperature changes will cause changes in the sealing pressure in the sealing zone, and even damage the seal. The impact on the sealing of low-temperature (or high-temperature) fluids is particularly significant. Most sealing materials fail at low or high temperatures. Therefore, the influence of temperature should be considered when selecting the sealing material.

The Influence of Surface Hydrophilicity

When there is a very thin oil film on the surface, it destroys the hydrophilicity of the contact surface and blocks the fluid channel, so that a large pressure difference is required to allow the fluid to pass through the capillary pores. Therefore, some globe control valves use sealing grease to improve sealing performance and service life. However, when using grease seals, attention should be paid to reducing the oil film and replenishing grease during use. And the grease used should not dissolve in the fluid medium, and should not evaporate, harden or other chemical changes.

LN Series 3 Way Globe Valve

LN Series 3 Way Globe Valve

The Structure and Size of the Sealing Pair

1. Under the influence of the sealing force or temperature changes, the structural size of the sealing pair will inevitably change, which will change the interaction force between the sealing pair, and the result is a reduction in the sealing performance. To compensate for this change, the seal should have a certain elastic deformation.

2. The influence of the width of the sealing surface.The width of the sealing surface determines the length of the capillary. Therefore, it is more important to choose the width of the sealing surface reasonably.

SUPCON has a field experienced and strong technical team, and also committed to the development of stringent complex working condition control valve, to solve high pressure, corrosion, flash, erosion, large differential pressure and a series of technical problems.

We have several types of globe control valves with good sealing performance for sale, if you are in need, please contact us!