In recent years, for
global gas industry highly developing, LNG has already become an important part of international gas trade. By 2020, LNG will account for 40% of gas trade volume and 15% of gas consumption.
Gas liquefying plant should be equipped with low temperature ball valve. So, the valve is popular.
Under the pressure of media, the floating ball of
low temperature ball valve may displace definitely and adpress the sealing face of outlet, maintaining the sealing of outlet.
Low temperature floating ball valve has simple structure and good sealing. However, all of media pressure bore by ball valve is transmitted to sealing ring of outlet. For this, endurance of sealing ring for pressure of media should be considered. When suffering from higher pressure impact, the ball of low temperature ball valve may extrude. The structure is generally suitable for medium or low pressure ball valve.
The main features of low temperature ball valve include compact structure, reliable sealing and convenience for maintenance. The sealing face and spherical surface are usually closed, in case of being eroded by media. Low temperature floating ball valve is easy for operation and maintenance, suitable for water, solvents, acids and gas. Moreover, low temperature floating ball valve is also fit for media having wicked conditions, such as oxygen, hydrogen peroxide, methane and ethylene. The valve has been widely applied in industries. The body of ball valve can be integral or composite.
Low temperature ball valve is developed from plug valve. The closure member of the ball valve is a ball. The ball rotates 90 degrees around the axis of stem for full-on or off. The parts are dipped into liquid whose temperature is -196℃, being cooled for 2 hours or 6 hours. Then, take it out. It reduces deformation caused by temperature difference and metallographic structure changing, highly improving the sealing of valve under low temperature. If the valve is used for flammable media, anti-static design is necessary. Low temperature floating ball valve adopts 2-piece or 3-piece.
