The invention of the ball valve can be considered a revolutionary development in the valve industry, providing many unique solutions to meet modern flow control requirements. However, its unique advantages did not manifest themselves initially. Early on, due to a lack of machining technology to produce truly spherical balls and limited use of sealing materials related to natural rubber, ball valves could not be applied in industrial settings.
During the period from World War II to the 1950s, processing technologies developed for wartime purposes introduced the unique advantages of ball valves into military applications. The development of synthetic materials like polytetrafluoroethylene (PTFE), commonly known by the brand name Teflon, paved the way for the industrial application of ball valves.
Today, ball valves are widely used for controlling the flow of liquids, gases, and even solids. These applications range from temperatures of -450°F (-267°C) to over 1600°F (871°C), and pressure ranges can extend from full vacuum to over 20,000 psi.
The development of ball valves in China originated from two independent systems and went through three main stages:
- First Stage (Late 1950s to Late 1970s): Exhibition of a floating ball valve from Japan in 1958 led to the development of the Q41 series floating ball valve and the Q47 series fixed ball valve, which was based on the structure of the fixed ball valve introduced from Japan’s KTM.
- Second Stage (Early 1980s to Late 1990s): After the reform and opening-up, China adopted American valve products and ASME/ANSI standards for valve design, manufacturing, and testing. This period saw the introduction of American standard ball valve products. A significant development was the establishment of the first Sino-foreign joint venture in 1992 between JAMESBURY from the United States and the original Shanghai Valve Factory. This venture introduced high-performance ball valves and high-performance butterfly valves based on the principle of media-induced flexible sealing, significantly raising the overall technical level of Chinese valves.
- Third Stage (21st Century Onwards): From the beginning of the 21st century, China achieved significant progress in long-distance pipeline ball valves and metal-seated ball valves.
The main components of a ball valve include the body, ball, seat, and stem, with various materials used for these components. The ball valve can provide multiple port connections, including flanged, threaded, welded ports, and wafer connections.
Body: The body of a ball valve can be made from various metals, including brass, bronze, aluminum, iron, carbon steel, stainless steel, nickel-based alloys, and reactive metals such as titanium, tantalum, and zirconium. Plastic and polymer materials, including PVC, polyethylene, and polypropylene, can also be used, either as the main material or as lining. The basic design of the body complies with ASME standards.
Ball: The flow control element of a ball valve is the ball. It acts on the seat to prevent or control the flow through the valve. Balls can be made from various materials, including metals, ceramics, or plastics. Metal balls may undergo coatings or surface treatments to enhance properties like wear resistance, corrosion resistance, or hardness.
Seat: Improvements in seat design and technology have expanded the application range of ball valves. Seats provide various functions depending on the valve design and seat material. Soft seat designs, often referred to as “cassette” or “flexible lip” designs, reduce torque and extend cycle life. Seat materials include rubber (e.g., chloroprene rubber and nitrile rubber), fluoropolymers (e.g., PTFE, TFM, PBI, and PFA), ultra-high-molecular-weight polyethylene (UHMWPE), polyetheretherketone (PEEK), Delrin, and nylon.
Stem: The stem is responsible for rotating the ball valve to the open or closed position or to an intermediate position for flow control. Stem materials need to withstand pressure from the body, ball, or seat, and maintain sufficient strength to handle the torque applied during valve operation. Common materials for stems include higher strength and corrosion-resistant materials.
The article also delves into the application of ball valves in various industries, including petrochemicals, water supply and drainage systems, power generation, food and pharmaceuticals, refrigeration and air conditioning systems, and marine engineering.
The compact design, simple operation, ease of maintenance, and versatile performance make ball valves a dominant design in modern industrial applications. As industries increasingly prioritize safety, environmental protection, efficiency improvement, and cost reduction, ball valves, with their unique value, play a crucial role in ensuring safe production and efficient operation in modern industry.