Recently, a batch of high-performance top entry ball valves with DN150-DN500 and PN100-PN180 have been successfully produced and passed various tests in our RAYS factory. All the valves have been delivered to our foreign customers at the end of September 2020 and will be put into use for a large natural gas project.
The valve body for this order is forged by integrated forging. Compared to casting, the mechanical property is more stable and reliable under the working condition of gas medium at minus 60 degrees. All of the workpiece was machined by CNC lathe and machining center, which ensures the shape, position tolerance, and accuracy of the workpiece. In addition, the ball and valve seat products adopt: cemented carbide spraying technology, the sealing surface hardness is high, wear-resisting, high temperature resistance, erosion resistance, and other excellent characteristics.
The finished product test after assembly simulated the gas working condition of the user. After nitrogen high-pressure gas test, the hard contact sealing surface reached the standard of zero leakage.
Structure and characteristics of top entry ball valve
Top entry ball valve is used mainly in pipeline and industrial systems which can utilize inline maintenance. Its main features are: simple structure design, low flow drop, compact size, light weight, reliable sealing, and quick open/close. The operation methods can be: manual, gear, pneumatic, electric, gas-over-oil, electro-hydraulic, and others.
Top entry ball valves differ from other standard ball valves is that it can be maintained online without removing from the line. It reduces maintenance costs and extends service life. The welded end structure is installed on the pipe, which is not affected by the pipe stress and objectively reduces the leakage point while ensuring the sealing reliability.
Seat sealing include: seat, seat insert, and other components. Seat inserts can float independently in the axial position and seal the seat at zero pressure/low pressure by preloading the spring. This design is used to realize the ability to turn off the quality under working pressure and high pressure conditions. On the outside of the seat insert, we insert the O-ring and the elastic ring to ensure the seal between the seat and body. The expanded graphite also retains the seal in case of field fire to ensure the reliability of the valve seat against fire.
When the valve seat and stem seal are damaged, leak occurs. The sealing grease injected by the grease valve can achieve the function of emergency sealing. Under the normal working condition of the valve, the valve stem and sphere can be lubricated by injecting grease through the grease valve, making the valve more flexible and portable.
For buried valves, the valve stem can be extended according to the installation and operation needs. The size of the extension stem will be according to customer requirements. All blowdown pipes, vent pipes and emergency injection devices shall be extended accordingly. Other related pipes shall be attached to the extended part of the valve to connect the: blowdown valve, vent valve, and injection valve to the ground for installation in order to facilitate the regular maintenance of the main valve.
The upper and lower stems (trunnion) are designed against static according to API 6D and IS0 17292.
While the upstream uses the single piston seat, the downstream uses the double piston seat which has the double blocking function and can cut off from the upstream/downstream media at the same time. With automatic directional pressure relief function, the valve seat can automatically relieve pressure (discharge to the upstream side) when abnormal pressure boost occurs due to temperature increase of the medium trapped in the valve chamber.
The top entry ball valve is a trunnion mounted type where the surface of the ball is: grinded, polished, and hardened. A sliding bearing is fitted between the ball & stem to minimize friction and operating torque.
Connection flanges between valves & actuators comply with ISO 5211 to make them more adaptable and interchangeable. Conventional operation methods include: manual, pneumatic, electric, gas-over-oil, electro-hydraulic, and so on.
