Main Technical Performance of Industrial Valves

In the field of industrial fluid control, valves act as the “heart” of the pipeline network system, and their technical performance directly determines the system’s safety, stability, and economy. Whether in petrochemicals, power generation, or water supply and drainage engineering, the selection and application of valves must be based on a deep understanding of their core technical performance. This article will systematically analyze the key technical indicators of valves and their engineering application value from the perspectives of sealing performance, flow resistance, actuation characteristics, control accuracy, and durability.

1. Sealing Performance: The Core Barrier for Safe Operation

Sealing performance is the most critical technical indicator for a valve, representing its ability to prevent media leakage. It covers a dual protection system for both internal and external leakage.

• Internal Leakage Control: Occurs at the sealing surface between the closing element and the valve seat, manifesting as a “failure to shut off completely.” For shut-off valves (e.g., gate valves, globe valves), internal leakage directly undermines the media cut-off function, leading to system pressure loss or backflow. In high-pressure gas or toxic chemical media transport, internal leakage can even trigger catastrophic accidents. International standards like API 598 specify internal leakage classes for shut-off valves, requiring zero or extremely low leakage rates.
• External Leakage Protection: Occurs at the interface between the stuffing box and the stem, as well as the joint between the valve body and bonnet, resulting in media leaking to the external environment. External leakage not only causes material loss but can also lead to environmental pollution, fire and explosion (for flammable media), or personal injury (for corrosive media). For special applications like nuclear-grade valves and cryogenic valves, external leakage control must meet “bubble-tight sealing” standards, achieved through multiple sealing structures (e.g., a combination of bellows and packing) for dual insurance.

2. Flow Resistance: A Key Parameter for Energy Saving

The flow resistance of a valve is represented by the pressure drop (ΔP

), which is the pressure loss of the medium as it flows through the valve. According to Bernoulli’s equation, pressure loss is positively correlated with the square of the flow velocity and the complexity of the flow path structure, directly affecting system energy consumption.

• Energy-saving Design: In high-flow scenarios like long-distance pipelines or circulating water systems, choosing low-resistance valves (e.g., ball valves, butterfly valves) can significantly reduce pump power requirements. For instance, a petrochemical project reduced system energy consumption by 18% and saved over a million yuan in electricity bills annually by replacing globe valves with full-bore ball valves.
• Flow Coefficient (Cv value): As a quantitative indicator, the Cv value represents the valve’s flow capacity at a specific pressure drop. In engineering design, the Cv value must be calculated precisely based on media flow and pressure parameters to avoid excessive pressure drop due to high flow resistance or vibration and noise caused by a low flow resistance.

3. Actuation Characteristics: Core Indicators of Operational Performance

Actuation force and torque are key indicators for measuring the ease of valve operation, influenced by factors such as sealing stress, friction pair design, and transmission mechanism efficiency.

• Dynamic Load Characteristics: During closing, the valve must overcome the contact stress of the sealing surface (2-5 times the media pressure) and the friction of the packing. When opening, it must break through static friction resistance, leading to a non-linear change in torque during the actuation process. Electric valves need to be equipped with torque sensors to prevent overload, while manual valves use a worm gear mechanism to amplify the torque.
• Actuation Speed Control: Special applications have strict requirements for actuation speed: emergency shut-off valves must close in ≤1 second to block hazardous media, while control valves in heating networks need to open and close slowly (5-10 seconds) to avoid water hammer. Actuation speed can be precisely controlled using devices like dampers and variable-frequency motors.

4. Control Accuracy: Core Competitiveness for Control Valves

For control valves, such as globe control valves and pressure reducing valves, action sensitivity and reliability determine the system’s regulation accuracy.

• Sensitivity Indicators: The minimum detectable pressure drop (e.g., 0.01 MPa) and minimum adjustment amount (e.g., 0.5% travel) reflect the valve’s response to changes in media parameters. In precision hydraulic systems, proportional valves need to achieve flow control accuracy of 0.1%.
• Reliability Design: Structures like disc guides and balanced plugs are used to reduce the risk of sticking, while intelligent diagnostic systems (e.g., fault self-diagnosis in valve positioners) enable predictive maintenance. In the pressure control system of nuclear power plant pressurizers, the reliability of high-precision control valves directly affects reactor safety.

5. Service Life: The Ultimate Consideration for Economy

Service life is measured in “actuation cycles” or “service time” and is influenced by factors like material corrosion resistance, sealing surface wear resistance, and fatigue strength.

• Material Matching: Valves in seawater desalination plants must use duplex stainless steel (e.g., 2205) to prevent chloride ion corrosion, while those in coal chemical applications require hard alloy (e.g., WC-Co) overlay welding on the sealing surface to resist particle erosion. An LNG project extended the valve service life from 3 years to 10 years by selecting nickel-based alloy valves.
• Failure Mode Analysis: Through FMEA (Failure Mode and Effects Analysis), major failure modes like sealing surface wear and stem fracture are identified, allowing for optimization of heat treatment processes (e.g., nitriding to increase surface hardness) and structural design (e.g., adding stem protective sleeves). The industrial valve standard JB/T 12622 stipulates that the service life of general-purpose valves should be ≥5000 actuation cycles.

6. Synergistic Performance Optimization and Engineering Selection

In practical applications, a valve’s technical performance indicators need to be synergistically designed: under high-pressure conditions, sealing stress and actuation torque must be balanced; in high-temperature environments, material thermal expansion and sealing reliability must be considered; and for corrosive media, a trade-off is needed between corrosion resistance and flow resistance. The selection process should follow the “operating condition first” principle:

• Clarify media characteristics (temperature, pressure, corrosiveness, viscosity).
• Determine functional requirements (shut-off, regulation, safety relief).
• Quantify performance indicators (leakage rate, flow resistance, actuation time).
• Consider economy (initial cost vs. lifecycle cost).

The technical performance of valves is a concentrated embodiment of design innovation and engineering practice. From the micron-level precision of sealing structures to the reliability management of the entire lifecycle, each indicator carries the dual mission of industrial safety and efficiency. With the development of new energy, high-end equipment, and other fields, valves are evolving towards high parameters (ultra-high pressure, ultra-low temperature), intelligence (IoT monitoring), and green design (zero-leakage design). When selecting valves, enterprises should establish a multi-dimensional evaluation system, while manufacturers should continuously improve the core performance indicators of valves through material innovation, structural optimization, and digital testing to provide more reliable solutions for industrial fluid control.