What are the drawbacks of using gate valves for regulation?

2026-06-01

The core design function of a Gate Valve is to cut off the medium viafull opening and full closing, which is only applicable to full flow or full cut-off working conditions without flow regulation attributes. Forcing a gate valve to serve as a regulating valve to control medium flow by adjusting its opening will cause a series of problems such as poor accuracy, rapid valve damage, potential equipment hazards and increased energy consumption due to its inherent structural characteristics. The specific disadvantages are detailed as follows:

1. Extremely Poor Regulation Accuracy and Unstable Flow Operation

The gate valve adopts a straight-through flow channel structure, and there is a severely non-linear relationship between the vertical lifting opening of the gate plate and the medium flow rate, making precise and stable flow regulation impossible throughout the operation process.

Under small opening conditions (10%-30%), a narrow throttling gap is formed between the gate plate and the valve seat, causing the medium flow velocity to rise sharply, with the local flow velocity reaching 5-10 times that of normal working conditions. In this state, the flow rate is extremely sensitive to pipeline pressure changes, and tiny pressure fluctuations will lead to severe flow oscillations, completely invalidating the regulation stability.

Under large opening conditions (above 70%), the pipeline flow rate approaches saturation. Further increasing the gate opening barely changes the flow rate, making fine and precise flow adjustment unachievable.

Typical Case: A chemical plant adopts gate valves to regulate the feed flow of reaction kettles. When fixed at a 30% opening, the actual flow rate fluctuates between 50% and 150% of the designed value, directly causing unbalanced reaction concentration and affecting product quality.

2. Severe Scour Wear on Sealing Surfaces and Greatly Reduced Valve Service Life

The sealing of gate valves relies on the metal hard seal or rubber soft seal structure between the gate plate and the valve seat, which is only adapted to static and steady-state working conditions of full opening and full closing. When operating under throttling and regulation conditions with the valve partially open for a long time, the high-speed medium continuously impacts and scours the edge of the gate plate and the sealing surface, causing persistent cavitation and scour wear. The wear is exponentially aggravated if the medium contains solid particles.

For metal-sealed gate valves conveying media such as sand-containing sewage, the sealing surface will be scoured with grooves in a short period, resulting in internal valve leakage. For rubber soft-sealed gate valves under throttling conditions, the high-speed medium will directly damage the rubber sealing components, forming and expanding gaps and worsening leakage. Data shows that the service life of gate valves used for long-term flow regulation is only 1/5 to 1/10 of that under normal cut-off working conditions.

3. Prone to Sticking and Vibration, Causing Potential Safety Hazards

1. Gate Plate Sticking Failure: During valve regulation, gaps between the gate plate and valve seat easily trap solid particles and crystalline impurities in the medium (such as scale in power plant steam pipelines and crystals in chemical slurry), causing jamming and stalling of the gate plate during lifting and lowering. In severe cases, the valve cannot be fully closed to cut off the medium, requiring frequent disassembly and cleaning and increasing operation and maintenance workload.

2. High-Frequency Vibration Hazards: The medium forms intense turbulence when passing through the throttling gap, driving high-frequency vibration of the gate plate. Long-term vibration will loosen the connecting structure of the valve stem and cause failure and leakage of the packing seal. Accumulated fatigue damage may even lead to valve stem fracture, resulting in medium leakage, system shutdown and other safety accidents.

4. Increased Pipeline Resistance and Rising System Energy Consumption & Operating Costs

Compared with dedicated regulating valves, gate valves have a greatly increased local resistance coefficient and pipeline flow resistance under partial opening and throttling conditions. Taking a DN100 gate valve as an example, the resistance coefficient at 30% opening is more than 20 times that at full opening, equivalent to adding a throttling plug inside the pipeline.

To offset the additional resistance and maintain normal process flow, power equipment such as water pumps need to operate at higher power, resulting in an extra power consumption of 30%-50% and substantially increased long-term power costs. Meanwhile, excessive throttling loss in high-temperature and high-pressure steam systems of power plants causes ineffective medium energy loss and directly reduces the operating efficiency of the entire process system.

Conclusion and Application Recommendations

Using gate valves for flow regulation is a typical function mismatch, analogous to "cutting hair with a kitchen knife", which violates the original design logic of the equipment. The structural properties of gate valves determine that they are only suitable for on-off working conditions of "full closing for flow cut-off and full opening for smooth flow". For flow regulation working conditions, dedicated valves with linear opening-flow correspondence, scour resistance and low throttling resistance (such as Globe Valves, V-port ball valves and dedicated regulating valves) shall be adopted.

If gate valves have to be used for temporary emergency flow regulation due to on-site constraints, the equipment maintenance cycle must be shortened (monthly inspection of sealing surface wear is recommended). Long-term use under harsh working conditions with high pressure, high solid content and high-precision flow regulation requirements is strictly prohibited, so as to avoid premature valve scrapping, unstable system operation and prevent safety accidents such as leakage and shutdown.