How Can The Reliability of Fully Welded Ball Valves Be Achieved under Harsh Working Conditions

Impact of Severe Operating Conditions on Fully Welded Ball Valves

• High-temperature environments: High temperatures may lead to a decline in material performance, such as reduced strength and accelerated creep, which in turn affect the sealing performance and structural integrity of the valve.

• High-pressure working conditions: High pressure increases the difficulty of valve sealing, especially with extremely high requirements for sealing surfaces and valve seats. At the same time, high pressure may also cause fatigue failure of valve components.

• Strongly corrosive media: Chemical corrosion can erode metal components of the valve, especially the sealing surfaces and valve body, shortening the service life of the valve.

• Frequent operation: Frequent opening and closing operations will increase the wear of the valve, especially the valve stem and sealing surfaces, which may lead to leakage or operational difficulties.

• Low-temperature environments: Low temperatures may increase the brittleness of materials and harden the sealing materials, affecting the sealing performance and flexibility of the valve.

Strategies to Improve the Reliability of Fully Welded Ball Valves

(I) Design Optimization

Integrated structural design

• Integrated welded structure: Adopt integrated welding technology to reduce connection parts, enhance the overall strength and sealing performance of the valve. The integrated structure can effectively avoid leakage risks caused by welded joints.

• Streamlined design: Optimize the streamlined design of the ball and valve body to reduce fluid resistance, lower energy loss, and reduce structural stress caused by fluid impact.

• Stress analysis and optimization: Use Finite Element Analysis (FEA) technology to simulate the stress distribution of the valve under different working conditions, optimize the structural design, and ensure the structural stability of the valve under extreme conditions such as high temperature and high pressure.

Sealing system design

• Multi-stage sealing structure: Adopt a multi-stage sealing design, including a combination of hard sealing and soft sealing. Hard seals (such as metal sealing surfaces) can withstand high temperatures and pressures, while soft seals (such as reinforced polytetrafluoroethylene) provide good sealing performance, ensuring sealing reliability under different working conditions.

• Dynamic sealing technology: Introduce dynamic sealing technologies, such as self-compensating sealing systems, which can automatically adjust the sealing force during valve operation, compensate for sealing gaps caused by wear or temperature changes, and ensure the durability of sealing performance.

• Sealing surface protection: Perform special treatments on sealing surfaces, such as spraying wear-resistant coatings (e.g., tungsten carbide) or using surface hardening technologies (e.g., nitriding), to enhance the wear resistance and corrosion resistance of the sealing surfaces.

Operating mechanism design

• Low-torque design: Reduce operating torque by optimizing the design of the valve stem and bearings. For example, use bearing materials with low friction coefficients and lubrication technologies to reduce energy consumption during operation and extend the service life of the valve stem.

• Anti-seizing design: Set anti-seizing devices between the valve stem and valve body, such as spring compensation mechanisms or automatic lubrication systems, to prevent seizing caused by high temperatures or corrosion and ensure flexible operation of the valve under severe working conditions.

(II) Material Selection

Valve body materials

• High-temperature alloys: For high-temperature working conditions, select high-temperature alloy materials such as INCONEL 625 and INCONEL 718. These materials have excellent creep resistance and oxidation resistance, and can maintain structural stability in high-temperature environments.

• Corrosion-resistant alloys: For strongly corrosive media such as acids and alkalis, select duplex stainless steels (e.g., 2205, 2507) or super austenitic stainless steels (e.g., 904L). These materials have good corrosion resistance and mechanical properties, and can effectively resist erosion by chemical media.

• Low-temperature steels: For low-temperature working conditions, select low-temperature steel materials such as 304L and 316L, which have good toughness and resistance to brittleness in low-temperature environments, ensuring the normal operation of the valve.

Sealing materials

• High-performance polymers: Use high-performance polymers such as polytetrafluoroethylene (PTFE) and polyetheretherketone (PEEK) as soft sealing materials. These materials have excellent chemical corrosion resistance and temperature resistance, and can maintain good sealing effects under various severe working conditions.

• Metal sealing materials: For high-temperature and high-pressure working conditions, use metal sealing materials such as cemented carbides (e.g., tungsten carbide) or stainless steel. Metal seals can withstand higher pressures and temperatures, and have good wear resistance and corrosion resistance.

• Composite sealing materials: Combine the advantages of soft and hard seals to develop composite sealing materials. For example, adopt a combination of metal sealing surfaces and polymer sealing rings to ensure sealing performance while improving wear resistance and corrosion resistance.

Surface treatment technologies

• Wear-resistant coatings: Apply wear-resistant coating treatments to key components (such as valve stems and sealing surfaces) by spraying hard materials such as tungsten carbide and titanium carbide. These coatings can significantly improve the wear resistance and corrosion resistance of components, extending their service life.

• Anti-corrosion coatings: Use anti-corrosion coatings such as epoxy resin and polyurethane to protect the valve body and external components, preventing corrosion caused by chemical media or environmental factors.

• Surface hardening treatment: Improve the surface hardness and wear resistance of components through surface hardening technologies such as nitriding and carburizing, enhancing their performance under severe working conditions.

(III) Improvement of Manufacturing Processes

Welding process

• Automated welding technology: Adopt advanced automated welding equipment and processes to ensure the stability and consistency of welding quality. Automated welding can reduce the impact of human factors, improve welding efficiency and precision.

• Welding quality inspection: During the welding process, use non-destructive testing technologies (such as X-ray testing and ultrasonic testing) to conduct real-time inspection of welded joints, timely detect and handle welding defects, and ensure welding quality.

• Heat treatment process: Perform appropriate heat treatment on the welded valve body, such as annealing and normalizing, to eliminate welding stress, restore the mechanical properties of materials, and improve the overall reliability of the valve.

Precision machining process

• High-precision machining equipment: Use high-precision CNC machining centers and grinders for precision machining of key valve components (such as balls, valve seats, and valve stems) to ensure dimensional accuracy and surface finish, improving sealing performance and operational flexibility.

• Machining process monitoring: Introduce real-time monitoring systems during the machining process to dynamically adjust machining parameters and ensure the stability of machining quality. For example, through a tool wear monitoring system, timely replace worn tools to avoid machining defects.

• Quality inspection and control: Establish a strict quality inspection system, conduct 100% inspection of processed components, including dimensional inspection, surface quality inspection, and functional testing. Only components that pass strict inspections can enter the assembly process to ensure high product quality.

Assembly process

• Standardized assembly procedures: Formulate standardized assembly process flows to ensure the standardization and consistency of each assembly step. Through standardized operations, reduce assembly errors caused by human factors and improve assembly quality.

• Assembly process inspection: During the assembly process, use methods such as torque detection and sealing performance detection to conduct real-time monitoring of assembly quality. For example, use torque sensors to detect the assembly torque of the valve stem, ensuring it is within the specified range, and avoiding assembly problems caused by excessive or insufficient torque.

• Post-assembly functional testing: Conduct comprehensive functional testing on the assembled valve, including pressure testing, sealing performance testing, and operational flexibility testing. Only valves that pass all functional tests can leave the factory to ensure product reliability and safety.