SCH8O/DIN UPVC/CPVC Gear Butterfly Valve

How to maintain UPVC/CPVC gear butterfly valves? Common faults and ways to extend life

UPVC (unplasticized polyvinyl chloride) and CPVC (chlorinated polyvinyl chloride) gear butterfly valves are widely used in many industries due to their excellent corrosion resistance, lightweight design and economy, including safe drinking water, metallurgy, photovoltaics, nuclear power, electronic semiconductors, medicine, industrial water treatment, industrial wastewater and other fields. However, problems such as wear, leakage or poor operation may occur during long-term use. Reasonable maintenance and troubleshooting can significantly extend the life of the valve.

I. Daily maintenance measures

1. Regular inspection and cleaning
Safe drinking water & industrial water treatment: The valve is in contact with water containing chlorine or impurities for a long time. It is necessary to check whether there is sediment or biofilm inside the valve body to prevent blockage or corrosion.
Electronic semiconductor & pharmaceutical industry: high-purity water or chemical delivery systems need to ensure that the valves are free of particle contamination and are regularly flushed with deionized water or compatible solvents.
Metallurgy & industrial wastewater: Acidic or high-solid content media are prone to scaling on the valve seat or butterfly plate surface, and manual cleaning is required during shutdown.

2. Gearbox lubrication and operation test
The gear transmission mechanism needs to be regularly filled with food-grade grease (such as the drinking water industry) or chemical corrosion-resistant lubricant (such as the chemical industry and wastewater treatment industry).
Manually operate the valve several times to ensure smooth opening and closing and avoid jamming (the nuclear power industry has extremely high requirements for valve reliability and requires strict testing).

3. Seal inspection and replacement
The EPDM or FKM seals of UPVC/CPVC valves are prone to aging in high temperatures or strong chemical media (such as pickling fluids in the photovoltaic industry and etching agents in the semiconductor industry). It is recommended to replace them every 2-3 years.
If internal leakage is found (such as the strict sealing requirements in the pharmaceutical industry), it is necessary to immediately check whether the sealing surface is worn or deformed.

Ⅱ. Common faults and solutions

1. The valve cannot be completely closed (internal leakage)
Reason: Butterfly plate offset, seal ring wear or medium crystallization (such as salt deposition in industrial wastewater).
Solution: Adjust the gearbox limit screw, replace the seal ring, or disassemble and clean the butterfly plate (applicable to corrosive fluids in the metallurgical industry).

2. Increased operating torque or jamming
Reason: Lack of lubrication in the gearbox, rust on the valve stem (anti-rust design is required for cooling water systems in the nuclear power industry) or adhesion of the medium (such as syrup fluids in the pharmaceutical industry).
Solution: Clean and lubricate the valve stem, and check whether the gearbox has water ingress (waterproof design is required for outdoor installation valves in the photovoltaic industry).

3. Cracked or deformed valve body
Reason: CPVC valve exceeds the rated temperature (usually ≤90°C) at high temperature (such as high-temperature circulation of ultrapure water in the semiconductor industry), or UPVC valve is impacted by external force (such as mechanical stress in industrial wastewater pipes).
Solution: Replace CPVC or FRPP valves with higher temperature resistance and reinforce pipeline support.

4. Gearbox failure
Reason: Long-term exposure to humid environments (such as drinking water treatment plants) causes internal gears to rust, or frequent operation causes wear.
Solution: Choose a stainless steel gearbox model, or upgrade to an anti-corrosion coated gearbox (suitable for high-demand scenarios such as nuclear power).

III. Key methods to extend life

Adaptive media characteristics:
CPVC+PTFE seals are used in strong acid/alkaline environments (such as electronic semiconductor etching liquid);
High-purity water (pharmaceuticals, photovoltaics) avoid using lubricants containing metal additives.

Standardized installation and operation:
Avoid pipeline stress distortion of the valve body (a common problem in industrial water treatment);
The nuclear power industry must strictly perform pressure tests in accordance with ASME standards.

Preventive maintenance plan:
Check the sealing of safe drinking water systems every six months;
Clean and scale the industrial wastewater treatment valves every quarter.

IV. Special considerations in industry applications

Photovoltaic & electronic semiconductors: Valves must meet the requirements of no metal ion precipitation to avoid contaminating ultrapure water.
Nuclear power: Select CPVC materials that are resistant to radiation aging, and perform non-destructive testing (such as ultrasonic testing) regularly.
Medicine & Food: Valves must comply with FDA or EHEDG certification to ensure cleanliness and sterility.