Which One To Choose for Emergency Shut-off Working Conditions? Risk Assessment of Ball Valve's 0.5-second Quick Closure Vs. Gate Valve's Slow Operation

In industrial production, energy transmission, chemical engineering and other fields, emergency shut-off working conditions are a crucial link to ensure the safe operation of systems. VALVES, as the core components of fluid control systems, play a vital role in emergency shut-off working conditions. BALL VALVES and gate valves are two common types of valves, and they have different characteristics in emergency shut-off working conditions. Through comparative analysis, this article will explore the risk assessment of the ball valve's 0.5-second quick closure and the gate valve's slow operation, helping you make a wiser choice in practical applications.

I. BASIC CHARACTERISTICS OF BALL VALVES AND GATE VALVES

(1) Ball Valves
A ball valve is a type of valve that controls the on-off of fluid by rotating the ball. Its main features include:

• Quick opening and closing: It is easy to operate. Only a 90° rotation is needed to complete the on-off operation, and it can cut off the fluid in a very short time.
• High sealing performance: The ball fits tightly with the valve seat, providing excellent sealing performance and being suitable for various media.
• Compact structure: It has a small size and light weight, which is convenient for installation and maintenance.

(2) Gate Valves
A gate valve is a type of valve that controls the on-off of fluid by the up-and-down movement of the gate. Its main features include:

• Full-bore design: There is little resistance when fluid passes through, which is suitable for working conditions with large flow rates.
• High temperature resistance: It can withstand relatively high temperatures and is suitable for high-temperature steam systems.
• Good sealing performance: The double-gate design can provide reliable bidirectional sealing.

II. COMPARISON OF THE PERFORMANCE OF BALL VALVES AND GATE VALVES IN EMERGENCY SHUT-OFF WORKING CONDITIONS

The following is a specific comparison of ball valves and gate valves in emergency shut-off working conditions:

III. RISK ASSESSMENT OF BALL VALVES AND GATE VALVES

(1) Risk Assessment of Ball Valves

• Risks of Quick Closure

• Water Hammer Effect: The quick closure of the ball valve may cause the fluid pressure to rise instantaneously, resulting in the water hammer effect. The water hammer effect will impact the pipeline system and may lead to accidents such as pipeline rupture and flange leakage.

• Solutions: Install a buffer device (such as a water hammer arrester) at the rear end of the ball valve or adopt the soft closing technology to slow down the closing speed and reduce the risk of the water hammer effect.

• Risk of Seal Failure

• Medium Corrosion: The sealing materials of the ball valve (such as PTFE) may fail in some corrosive media, resulting in a decline in sealing performance.

• Solutions: Select sealing materials with strong corrosion resistance (such as metal seals), or regularly check the wear of the sealing materials and replace them in a timely manner.

(2) Risk Assessment of Gate Valves

• Risks of Slow Operation

• Delayed Emergency Shut-off: The closing speed of the gate valve is relatively slow, which may lead to the expansion of accidents in emergency situations. For example, in the event of a fire or leakage accident, the gate valve cannot cut off the fluid in time, which may lead to greater losses.

• Solutions: Try to avoid using gate valves in working conditions that require quick shut-off, and use ball valves or other quick shut-off valves instead.

• Risk of Seal Failure

• Gate Wear: The gate of the gate valve is prone to wear during frequent operations, resulting in a decline in sealing performance.

• Solutions: Regularly check the wear of the gate and repair or replace it in a timely manner. Meanwhile, choose high-quality gate valves to ensure their durability and reliability.

IV. SELECTION SUGGESTIONS UNDER EMERGENCY SHUT-OFF WORKING CONDITIONS

(1) Selection Based on Closing Speed

• Quick Shut-off Requirement: If the system needs to quickly cut off the fluid in emergency situations to prevent the expansion of accidents (such as fire, leakage, etc.), it is recommended to give priority to ball valves. The quick closing ability of ball valves can cut off the fluid in a short time and reduce the accident risk.

• Non-emergency Shut-off Requirement: If the system does not have high requirements for the closing speed and pays more attention to the smooth flow of the fluid and the sealing performance, gate valves are a good choice. The full-bore design and good bidirectional sealing performance of gate valves make them perform excellently in high-temperature, high-pressure, and large-flow working conditions.

(2) Selection Based on Working Condition Characteristics

• High-temperature and High-pressure Working Conditions: The high temperature resistance and good sealing performance of gate valves make them perform excellently in high-temperature and high-pressure steam systems and boiler feedwater systems. If the working temperature is relatively high (such as exceeding 300 °C), gate valves are a more reliable choice.

• Frequent Operation Working Conditions: Ball valves are easy to operate and have a fast opening and closing speed, which are suitable for working conditions that require frequent operations. For example, in drainage systems, bypass systems and other parts that need to quickly adjust the flow rate, ball valves can effectively improve the operation efficiency.

(3) Selection Based on Risk Assessment

• High-risk Working Conditions: In high-risk working conditions (such as fire, leakage, etc.), quick shut-off is the key to ensuring the safety of the system. The quick closing ability of ball valves can effectively reduce the accident risk, and it is recommended to give priority to them.

• Low-risk Working Conditions: If the working conditions are relatively stable and there is no high requirement for the closing speed, the durability and sealing performance of gate valves can ensure the long-term stable operation of the system, and they are a more economical choice.

V. SUMMARY

In emergency shut-off working conditions, BALL VALVES and GATE VALVES each have their own unique advantages and risks. BALL VALVES can quickly cut off the fluid in emergency situations due to their quick closing ability, reducing the accident risk, but the quick closure may lead to the water hammer effect; while GATE VALVES perform excellently in high-temperature, high-pressure, and large-flow working conditions due to their high temperature resistance and good sealing performance, but the closing speed is relatively slow and may delay the emergency shut-off time.

Through the comparative analysis and risk assessment in this article, it is hoped that valuable references can be provided for the selection of valves in emergency shut-off working conditions. In practical applications, appropriate valve types should be selected by comprehensively considering the specific requirements of the system (such as closing speed, working condition temperature, operation frequency, etc.) and the results of risk assessment to ensure the safe and stable operation of the system.