Key Insights for Effective Industrial Valve Procurement

In modern industrial production, valves play a crucial role as the core components of fluid control systems. Their performance, durability, and safety directly impact the efficiency and stability of the entire system. Therefore, selecting the right industrial valves requires not only technical expertise but also a deep understanding of the materials, designs, and functional characteristics of different valves. This article analyzes the key factors to consider when purchasing industrial valves, helping companies make informed decisions to ensure optimal performance in real-world applications.

Valve Material

The material of the valve is a critical factor affecting its performance and lifespan, making it essential to choose the right one.

1. Body Material

Ductile iron is recommended for the valve body due to its good mechanical strength, toughness, and corrosion resistance. When purchasing, provide specific material grades and include physical and chemical testing data to ensure compliance with industry standards. Also, consider the medium and environment the valve will be exposed to, as specific corrosion-resistant or high-temperature materials may be required.

2. Stem Material

The material of the stem affects its corrosion resistance and wear performance. Stainless steel stems, such as 2CR13, are recommended for their excellent oxidation resistance and mechanical properties, which can extend service life. For larger valves, stainless steel wrapped stems can enhance strength and durability.

3. Nut Material

Choose cast aluminum bronze or cast aluminum brass to ensure that the hardness and strength exceed those of the stem, preventing deformation or damage in high-pressure or severe working conditions.

4. Stem Bearing Material

The bearing should have lower hardness and strength than the stem to reduce wear risks. Additionally, the bearing material should not cause electrochemical corrosion with the stem and body when submerged in water, ensuring reliable long-term use.

Seal Face Material

The design and material of the sealing surface are crucial for the valve's sealing performance, requiring specific analysis based on the valve type.

Wedge Gate Valves: Clarify the material, fixation method, and grinding process of the copper ring, as these directly affect the effectiveness and reliability of the seal.
Soft-Seal Gate Valves: The physical and chemical properties of the rubber lining on the disc should be prioritized to ensure compliance with hygiene standards, particularly in industries like food and pharmaceuticals.
Butterfly Valves: Specify the sealing surface materials on both the body and the disc, providing detailed physical and chemical testing data. Pay special attention to the hygiene requirements, aging resistance, and wear resistance of rubber materials. Common rubber materials include nitrile rubber and EPDM; recycled rubber should never be used, as it can compromise sealing performance.

Stem Packing

The choice and design of packing directly relate to the valve's sealing ability and durability.

1. Long-term Sealing

Since valves in pipelines are not frequently opened or closed, the packing should maintain sealing ability for several years and effectively resist aging. Additionally, it should be designed to provide good sealing during frequent operations.

2. Design Requirements

Packing should be designed for easy replacement under water pressure to simplify maintenance. If replacement is necessary, design measures should allow for changes without disrupting system operation.

Gearbox

The design and material of the gearbox must meet strict standards to ensure reliable valve operation.

1. Housing Material and Corrosion Resistance

The housing material should match the valve body and include effective corrosion protection to prevent damage in humid or corrosive environments. The housing must withstand immersion in water up to 3 meters, ensuring long-term stability.

2. Limit Devices

The adjustment nut design should allow for easy operation, both inside and outside the housing, but should require specialized tools to prevent accidental misuse.

3. Drive Structure Design

A well-designed drive structure should ensure that only the valve stem rotates during operation, preventing vertical movement and ensuring proper engagement between drive components to avoid separation or slipping under load.

Operating Mechanism

The design of the valve's operating mechanism should prioritize ease of use and safety to enhance operational efficiency.

Opening and Closing Direction: All valves should have a uniform closing direction (clockwise) to simplify operation across different scenarios.
Turns for Opening and Closing: For large valves, the number of turns should be limited to 200-600 to reduce operational difficulty while ensuring safety and efficiency.
Operation End Design: The operating end of the valve should feature a standardized square design facing the ground for easy access by operators. Avoid using handwheel-operated valves in underground pipelines to minimize complexity.

Performance Testing

It's essential to conduct necessary performance tests before leaving the factory and during batch production to verify quality and reliability.

Batch Manufacturing Testing: Engage a reputable agency to test the valve's opening torque, continuous operation cycles, and flow resistance coefficients to ensure compliance with strict industrial standards.
Pre-Delivery Testing: Valves should undergo pressure tests at double the working pressure in the open state and withstand 1.1 times the working pressure in the closed state without leakage. For metal-sealed butterfly valves, the leakage rate must meet relevant standards to ensure reliability in actual operation.

Internal and External Corrosion Protection

Corrosion treatment is vital for extending the lifespan of valves.

1. Corrosion Treatment

The valve body and gearbox should undergo thorough sandblasting to remove rust, followed by electrostatic spraying of non-toxic epoxy resin, achieving a thickness of over 0.3 mm for excellent corrosion resistance.

2. Internal Corrosion Protection

The interior of the valve body must be fully treated to prevent rust when submerged and avoid electrochemical corrosion between different metals. The surface should be smooth to reduce fluid resistance and improve flow efficiency.

3. Hygiene Requirements

The internal corrosion protection epoxy resin or paint should have relevant authority testing reports to ensure compliance with chemical and physical performance standards, especially in food and pharmaceutical applications.

Conclusion

Considering these factors when purchasing industrial valves can significantly enhance their performance and lifespan. By focusing on materials, sealing, design, operability, and testing, companies can ensure that the selected valves are reliable and safe in practical applications, meeting the stringent demands of industrial production while improving overall efficiency and safety. Through a rigorous selection and evaluation process, businesses can gain a competitive edge in a challenging market.