1. Advantages:
(1) there is a minimum flow resistance (0);
2. It can be reliably used in corrosive medium and low boiling point liquid because it will not be stuck at work (without lubricant).
The complete seal can be realized in the larger pressure and temperature range.
4. Fast opening and closing can be realized. The opening and closing time of some structures is only 0.05~0.1s, so that it can be used in the automation system of the test rig. When the valve is opened and closed quickly, the operation is not impacted.
Spherical closure can be automatically positioned at the boundary position.
The working medium in the two-sided reliable seal;
In the fully open and fully closed, the ball and seat sealing surface and the dielectric isolation, the high-speed media through the valve sealing surface will not cause erosion;
It has the advantages of compact structure, light weight, it could be considered for most reasonable structure of the valve system of medium low temperature;
To body symmetry, especially the welded body structure, can well withstand the stress from the pipe;
The closure of parts can withstand the pressure differential.11;
They all welded ball valve can be buried underground, so that the valve parts from erosion, the maximum life of up to 30 years, is the most ideal oil and natural gas pipeline valve.
2. Shortcomings:
1. Because the main valve seat seal material of ball valve is polytetrafluoroethylene, it is inert to almost all chemicals, and has the comprehensive characteristics of small friction coefficient, stable performance, no aging, wide application temperature and excellent sealing performance. However, the physical properties of PTFE include higher expansion coefficient, sensitivity to cold flow and poor thermal conductivity, so the design of seat seal must be carried out around these characteristics. Therefore, when the sealing material becomes hard, the reliability of the seal is damaged. Moreover, the temperature resistance of polytetrafluoroethylene is low and can only be used at less than 180 degrees C. More than this temperature, the sealing material will age. In the case of long term use, it is generally not used at 120 degrees C.
Its adjustment performance is a little worse than the cut-off valve, especially the pneumatic valve (or electric valve).