TipValve Blog

Bi-directional Standard soft-seated ball valves can shut-off flow in either forward or reverse direction. As they have two soft seats and a pressure-assisted, floating ball. However, power plant ball valves are most uni-directional shut-off valves with a non-floating ball design. They have only one seat located downstream of the ball. This downstream seat, the upstream bearing ring, the conical load spring, and the ball are a matched set, fitted very precisely into the body cavity. Therefore, when assembled, the final stack height does not allow the ball to float.

Some power plant ball valve manufacturers are machining ball valve bodies from forged bar stock materials with massive wall thicknesses far exceeding that of rising stem valves. Some adopt the same ball valve body design on 1.5-inch and smaller sizes for all pressures classes—so that an ASME Class 1500 valve may actually have an ASME Class 4500 body. The standardization reduces raw material inventory, streamlines machining, shortens production times and allows for virtually unlimited alloy material selection. Usage is restricted by the pressure and temperature rating stated on the original equipment manufacturer (OEM) tag and relevant American Society of Mechanical Engineers (ASME) and American National Standards Institute (ANSI) standards.

The answer if metal-seated ball valves can provide effective long term, economical solutions for critical applications in steam-generating power plants lies in knowing the design limitations of the ball valve, in identifying the application requirements correctly and in the proper installation techniques. During the last 20 years, advances in machining, tooling, measuring and coating technology have led to the ball valve designs to provide positive sealing solutions for the power industry. These new “power plant ball valves” can withstand temperatures and pressures to make them a viable solution for the industry.

           Coatings protect ball valves against wear, erosion, chemical attack and other forces that threaten their durability and effectiveness. As they meet such a diversity of challenges, there are a broad number of differences in the types of coatings used. The coatings used for ball valves have their own characteristics that differ in many cases from other types of valves.

           Today’s newer, low-cost manufacturing sources, combined with a loss in U.S. manufacturing expertise, are creating increased scrutiny on ball valves and other piping components. Castings are especially vulnerable to poor quality and workmanship. Due to the nature of their potential defects, unaided visual examination is not enough to instill a sense of security with many ball valve users. Therefore, users often ask for additional nondestructive evaluation (NDE).

           Nowadays, the fire proof is one of important features that are required for the ball valves. Of course, the fire test becomes one of the important tests for the ball valve. We TIPVALVE can supply the various ball valves with fire-safe feature. 

         As the seat sealing material for ball valve are usually rubber, nylon and PTFE, its working temperature is limited by seat sealing material. Take floating ball valve for example; ball valve cut-off function is relying on the mutual compressing between the ball and plastic seat under the effect of media. Part of the Seat ring will appear elastic-plastic deformation under a certain contact pressure function, which can compensate the ball manufacturing precision and surface roughness, guaranteeing the ball valve sealing performance
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The desire to keep our nation’s air clean is manifested in the valve industry through the Clean Air Act and various state and local regulations. For manufacturers to meet today’s low emissions requirements, ball valves must be tested to determine their ability to contain these fugitive emissions (FE). FE testing is now a requirement by most refiners and chemical companies that must contain hazardous fluids as part of their everyday processes.

Pipeline safety is becoming more and more important due to catastrophic pipeline failures, which have occurred primarily on older pipelines because of the strict quality requirements for new pipeline. Ball valve for pipeline service is also scrutinized very closely. While all pipeline ball valves are hydrostatically tested at the factory, usually according to API 6D, additional tests are almost always performed. The most common extreme test for pipeline ball valves is a long duration shell test, which is carefully monitored by a recording device tracking the pressure and the temperature of the valve as it is tested.

            Its features: 1. Small hydraulic resistance, especially the ball valve has the smallest hydraulic resistance of all kinds of valves, even for the reduced ball valve.  2. Thrust bearing reduce the friction moment of stem which can makes the valve stem operate steadily and flexibly for long-term. 3. Good seat sealing performance adopts the elastic material such as PTFE to make the seal ring. With the structure which is easy to seal, the sealing ability of ball valve can be better with the medium pressure increases. 4. Reliable stem sealing performance, because the stem only does the reverse rotation movement but not does the lifting movement, the stem packing seal is not easy to be damaged and sealing ability can be better with the medium pressure increases. 5. Because PTFE material has good self lubrication and the loss of ball friction is small, the ball valve has long service life.  6. Anti-static function: setting the spring in the ball, valve stem and body makes the electrostatic derived which is produced in the opening and closing process.