Views: 0 Author: J-VALVES Publish Time: 2025-06-13 Origin: Site
High-temperature and high-pressure DOUBLE BLOCK AND BLEED FLANGED BALL VALVES are widely used in industries such as petroleum, natural gas, chemical engineering, and electric power. The working environments in these industries are usually extremely harsh, requiring the BALL VALVES to possess the following characteristics:
High-temperature adaptability: They should be able to maintain structural stability and sealing performance under extremely high temperatures.
High-pressure bearing capacity: Ensure that there will be no leakage or deformation under high-pressure working conditions.
Double block function: Achieve double isolation through two independent sealing surfaces to ensure the safety of the system during maintenance and inspection.
Bleed function: The intermediate bleed passage can effectively discharge the residual medium to prevent potential safety hazards caused by pressure accumulation and residual medium.
The body is the main structural component of the BALL VALVE and directly bears the pressure and temperature of the medium. Common body materials include carbon steel, stainless steel, and alloy steel.
Carbon steel: It has a relatively low cost and is suitable for working conditions with moderate temperature and pressure. Its disadvantages are that its strength and toughness may be insufficient under high temperature and high pressure, and it is prone to corrosion.
Stainless steel: It has good corrosion resistance and certain high-temperature performance. 304 stainless steel is suitable for mild corrosive environments, while 316 stainless steel performs excellently in more demanding environments. However, the strength of stainless steel may be limited under extremely high temperature and high pressure.
Alloy steel: Such as chrome-molybdenum steel (e.g., 1.25Cr0.5Mo and 1.5Cr1Mo) and nickel-based alloys (e.g., Inconel 625 and Inconel 825). These materials have excellent high-temperature strength and creep resistance and can remain stable under extreme conditions. Alloy steel is an ideal choice for high-temperature and high-pressure double block and bleed flanged ball valves, although its cost is relatively high.
The ball is the core component of the ball valve, and its material directly affects the sealing performance and service life of the valve.
Stainless steel ball: After nitriding treatment or surface hardening (such as hard chrome plating), the stainless steel ball can provide good sealing performance under moderate temperature and pressure. However, its wear resistance and anti-deformation ability may be insufficient in high-temperature and high-pressure environments.
Alloy steel ball: For example, a nitrided 410 stainless steel ball or a ball with a hardfacing alloy. These materials can maintain high hardness and good wear resistance under high temperature and high pressure. Especially the alloy steel ball with special treatment, such as spray welding with nickel-based alloy or chromium carbide coating, can significantly improve its anti-friction performance and service life.
Ceramic ball: Although ceramic materials have extremely high hardness and wear resistance, their application in high-temperature and high-pressure working conditions is limited due to their high brittleness.
The choice of seat material is crucial for the sealing performance of the BALL VALVE. Common seat materials include polytetrafluoroethylene (PTFE), metal alloys, and special materials.
PTFE seat: It has good chemical corrosion resistance and a low friction coefficient, and is suitable for mild corrosive environments and working conditions with relatively low temperatures. However, PTFE is prone to deformation under high temperature and high pressure, and its sealing performance will decline.
Metal seat: For example, a Stellite alloy seat has excellent high-temperature strength and wear resistance and can maintain good sealing performance under extreme conditions. Metal seats usually need to be used in combination with alloy steel balls to achieve two-way sealing and high-precision sealing.
Special seat materials: Such as special graphite (Graité) and metal alloy (Metaltite). These materials are suitable for high-temperature and high-pressure, flammable and corrosive environments and have extremely high reliability and sealing performance.
Besides the body, ball, and seat, the material selection of seals and other components also has an important impact on the overall performance of the ball valve.
Seals: Common seal materials include NBR (acrylonitrile-butadiene rubber), EPDM (ethylene-propylene-diene monomer rubber), and flexible graphite. NBR is suitable for working conditions with moderate temperature and pressure, while EPDM has better chemical corrosion resistance. Flexible graphite is suitable for high-temperature and high-pressure environments and can provide good sealing performance.
Other components: Components such as valve stems, bolts, and gaskets usually adopt stainless steel or alloy steel materials to ensure their strength and corrosion resistance under high temperature and high pressure.
The material selection for high-temperature and high-pressure DOUBLE BLOCK AND BLEED FLANGED BALL VALVES needs to comprehensively consider factors such as the working environment, medium characteristics, temperature, and pressure. The body material should preferably be stainless steel or alloy steel to meet the strength and corrosion resistance requirements under high-temperature and high-pressure environments. The materials of the ball and valve stem should be selected as appropriate stainless steel or alloy steel according to the corrosiveness of the medium. The sealing material should be selected according to the temperature, pressure, and medium characteristics. Metal sealing materials have more advantages in high-temperature and high-pressure environments. Through scientific and reasonable material selection, the performance and service life of high-temperature and high-pressure DOUBLE BLOCK AND BLEED FLANGED BALL VALVES can be effectively improved, ensuring the safe and stable operation of industrial systems.
