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Common Fault Causes, Troubleshooting Methods and Maintenance Recommendations for Wafer Check Valves
A wafer check valve is a type of valve that automatically opens and closes its disc relying on the flow of the medium itself to prevent medium backflow. It is widely used in high-pressure pipeline systems such as petroleum, chemical industry, and electric power. Its common faults mainly include disc damage and medium backflow. Troubleshooting shall be carried out in a targeted manner according to specific phenomena, and combined with standardized maintenance, which can effectively extend the service life of the valve and ensure the stable operation of the pipeline system.
I. Main Fault Causes and Troubleshooting Methods

(I) Disc Breakage or Damage

1. Fault Causes

When the medium pressure on both sides of the valve is close to equilibrium and “pulls back and forth” repeatedly, the disc will frequently hit the valve seat. If the disc is made of brittle materials such as cast iron and brass, it is very easy to break due to impact. In addition, the water hammer phenomenon (high-pressure shock wave generated by sudden stop or direction change of fluid) will make the disc bear an impact force far exceeding the normal pressure in an instant, leading to damage.

2. Troubleshooting and Preventive Measures

– Replace the disc material: Replace the disc made of brittle materials with materials with better toughness, such as stainless steel (304, 316) or alloy steel, to improve impact resistance.

– Optimize the structure: Prioritize the selection of double-disc swing type structure. This structure enables the disc to close quickly and synchronously and form a full-circle seal during reverse flow, significantly shortening the closing time and effectively reducing water hammer impact.

– Add buffer devices: Install a buffer cylinder in the pipeline system or directly use a slow-closing check valve to make the disc closing process smoother, absorb impact energy, and reduce disc wear.

– Reasonable selection: Select a valve model with sufficient strength according to the maximum possible water hammer pressure of the system to avoid disc damage caused by improper selection.

(II) Medium Backflow (Seal Failure)

1. Fault Causes

The core reason is that the disc cannot be completely closed or the sealing surface is not tight, leading to medium backflow, which is specifically divided into the following 4 situations:

– Wear or damage of the sealing surface: Long-term use, medium scouring, or hard particles contained in the medium will cause scratches, corrosion or deformation of the sealing surface, damaging the sealing performance.

– Impurity jamming: Welding slag, rust, sediment and other impurities in the pipeline enter the valve and get stuck between the disc and the valve seat, preventing the disc from closing completely.

– Poor disc guidance: The disc shakes radially during movement and cannot accurately return to the center of the valve seat, resulting in poor sealing.

– Spring failure (applicable to spring-assisted closing type): Insufficient elasticity, fracture or deformation of the spring cannot provide sufficient closing force, leading to the disc being unable to closely fit the valve seat.

2. Troubleshooting and Preventive Measures

– Clean impurities: Disassemble the valve, thoroughly clean the valve body, disc and sealing surface, remove all foreign objects, and ensure that the disc moves unobstructed.

– Repair or replace the sealing surface: For slight damage to the sealing surface, abrasive paste can be used for grinding and repair; if the damage is serious, the disc or valve seat seal ring needs to be replaced, and the material and performance of the spare parts must match the original parts.

– Check the guiding structure: Check whether the disc guiding mechanism (such as the guide sleeve) is intact, and ensure that the disc rises and falls smoothly along the vertical center line to avoid radial shaking.

– Replace the spring: For the spring-type check valve, it is necessary to replace it with a new spring that is completely consistent with the original spring in terms of elastic coefficient, material and size. After replacement, debugging shall be carried out to ensure that the closing force meets the standard.

– Clean the pipeline before installation: Before installing the valve, the pipeline system must be thoroughly flushed to remove internal impurities and avoid impurity jamming from the source.

(III) Slow Opening/Closing or Jamming

1. Fault Causes

Rust, poor lubrication of the disc moving parts (such as the rotating shaft and guide sleeve), or slight adhesion of impurities lead to blocked movement of the disc, resulting in slow opening/closing or jamming.

2. Troubleshooting and Preventive Measures

– Cleaning and lubrication: Regularly disassemble and inspect the valve, clean the moving parts, and add appropriate lubricant according to the medium characteristics (note that the lubricant must be compatible with the medium to avoid polluting the medium or affecting the valve performance).

– Check the installation direction: Confirm that the valve is correctly installed according to the medium flow direction indicated on the valve body. Incorrect installation direction will directly lead to abnormal opening and closing of the disc.

II. Maintenance Recommendations

– Regular inspection: It is recommended to conduct a comprehensive inspection of the valve every six months, focusing on checking the wear of the sealing surface and the flexibility of the disc movement, and timely detect and handle potential faults.

– Correct installation: Install in strict accordance with the product manual, ensure good pipeline support, and avoid the valve bearing additional stress; wafer check valves can usually be installed horizontally or vertically, and the installation requirements of the corresponding model shall be confirmed specifically.

– Source prevention: Install a filter upstream of the valve, which can effectively intercept impurities in the pipeline, reduce faults caused by impurities entering the valve, and is one of the most economical and effective preventive measures.