Common Faults and Solutions for Metal-Seated Ball Valves

 
 
Metal-seated ball valves are widely used in industries such as petroleum, chemical, and metallurgy due to their superior sealing performance and characteristics of high-temperature resistance and corrosion resistance. However, under extreme working conditions, these metal-seated ball valves may also encounter various faults, affecting their normal operation. Understanding the causes of these faults and taking effective improvement measures is crucial for enhancing the reliability and service life of the valves. This article will provide a detailed analysis of common faults in metal-seated ball valves and propose targeted improvement suggestions.

Valve Selection Errors

 
Choosing an inappropriate valve model is one of the main causes of faults. When selecting, it is necessary to comprehensively consider factors such as working temperature, pressure, and medium characteristics of the working conditions. Improper selection not only affects the performance of the valve but may also shorten its service life.

1. Incorrect Material Selection for Metal Seat Coating

 
The hardness and wear resistance of the metal seat layer directly affect the sealing performance and durability of the valve. For instance, using wear-resistant metal seat layers can reduce wear on the sealing surface caused by solid particles, while corrosion-resistant alloy layers can resist erosion from corrosive media such as strong acids and alkalis.

2. Material Selection of Valve Internals

 
The materials for internal components of the valve, such as packing, gaskets, and stem bushings, should be selected based on the actual temperature and nature of the medium of the working conditions. For example, graphite or metal materials can be used as sealing parts under high-temperature conditions, while synthetic plastics can be chosen for low-temperature conditions.

Accessory Selection Issues

 
The selection of accessories for metal-seated ball valves, such as actuators and supporting devices, is also crucial. Improper selection can affect the normal operation and effectiveness of the valve.

1. Pneumatic Actuators

 
Pneumatic actuators come in single-acting and double-acting types. When selecting, one should consider their torque output and adaptability. Single-acting pneumatic actuators rely on springs to return, suitable for applications that require quick closure; while double-acting pneumatic actuators provide greater torque, suitable for occasions that require higher operational precision.

2. Electric Actuators

 
Electric actuators are suitable for occasions that require remote control and precise operation. When selecting, one should consider the motor's power, control mode (such as on-off type, regulating type), and whether there are special requirements for explosion-proof.

3. Selection of Accessories

 
Accessories such as solenoid valves and pressure-reducing valves should match the specifications of the valve and its actuator to ensure system stability and normal valve operation.

Installation and Maintenance Issues

 
Improper installation and maintenance of the valve are also common causes of faults. Correct installation and regular maintenance can significantly improve the service life and performance of the valve.

1. Non-standard Installation

 
When installing, ensure that the direction and position of the valve are correct to avoid leaks or damage caused by improper installation. Especially at pipeline connections, ensure good sealing to prevent medium leakage.

2. Lack of Maintenance

 
Metal-seated ball valves require regular inspection and maintenance, including checking the sealing surface, cleaning solid particles, and adjusting packing. Regular maintenance can prevent the occurrence of valve faults and ensure normal operation of the valve.

Leakage Caused by Sealing Surface Damage

 
The sealing surface of the metal-seated ball valve is one of its key components. Damage to the sealing surface may lead to medium leakage, affecting the safety and stability of the system.

1. Sealing Surface Wear

 
Long-term use or in media containing solid particles, the sealing surface may experience wear. This can be reduced by selecting wear-resistant materials and increasing the hardness of the sealing surface.

2. Sealing Surface Corrosion

 
Corrosive media such as strong acids and alkalis may cause corrosion of the sealing surface. Choosing suitable materials and coatings, such as fluoride coatings or ceramic coatings, can improve the corrosion resistance of the sealing surface.

3. Sealing Surface Damage

 
Due to excessive operating force or improper operation, the sealing surface may be damaged. Appropriate sealing force and operating methods should be used to avoid excessive damage to the sealing surface.

4. Sealing Surface Maintenance and Repair

 
Sealing surface issues can be resolved by replacing sealing parts or on-site repair. When necessary, professional repair materials and techniques should be used to ensure the restoration of sealing performance.

Excessive Torque Value

 
In some harsh working conditions, the torque value of the valve may be too high, making it difficult to open and close the valve, and even causing it to jam.

1. Influence of Solid Particles

 
Media such as mud and dust may cause solid particles to accumulate inside the valve, increasing the opening and closing torque. Using a valve structure with a sweeping device or regularly cleaning the inside of the valve can effectively reduce particle accumulation.

2. Frequent Opening and Closing

 
Frequent opening and closing may lead to increased wear of the valve, increasing the operating torque. The frequency of opening and closing should be reasonably arranged according to the actual working conditions, and high wear-resistant materials should be used to reduce wear.

3. Hydraulic Impact

 
High-velocity or high-pressure fluids may increase the difficulty of valve operation. Optimizing the flow path design to reduce fluid impact and pressure fluctuations can reduce operating torque.

4. Optimization of Valve Drive System

 
Using high-torque drive devices and appropriate transmission ratios can effectively reduce the operating load and improve the efficiency of valve opening and closing.
 
Through in-depth analysis of common faults and their causes in metal-seated ball valves, targeted improvement measures can be taken to enhance the reliability and service life of the valves. Choosing appropriate materials, optimizing design, reasonable installation and maintenance, and addressing technical faults specifically will significantly improve the overall performance of the valve, meeting the needs of various complex working conditions.