Repairing Wear on Gate Valve Sealing Surfaces
Jan. 06, 2026
1. Impact of Sealing Surface Wear and Repair Principles
The sealing surface is the core part that determines whether a gate valve can be tightly closed. After long-term use of the gate valve, it is easily scoured by the medium in the pipeline, abraded by impurities, and affected by the impact force during valve opening and closing, leading to wear problems such as scratches, small pits, and grooves. This, in turn, causes medium leakage and affects the safe operation of the entire pipeline system. Therefore, when repairing a gate valve, corresponding methods should be selected according to the severity of wear to ensure both good repair quality and cost savings.
2. Mild Wear: Direct Grinding Repair is Sufficient
If the gate valve wear is not serious and there are no obvious grooves or deformations, it can be repaired directly by grinding. First, select an abrasive that matches the material of the sealing surface. For example, diamond abrasive is used for cemented carbide sealing surfaces, and alumina or silicon carbide abrasive is suitable for ordinary steel surfaces. Then, use a grinding plate or grinding ring of appropriate specifications. During operation, adopt a composite grinding method of "circular rotation + linear pushing" with uniform and stable grinding pressure until the gate valve's sealing surface is sufficiently smooth. After grinding, thoroughly clean the sealing surface with kerosene or absolute ethanol, and check the fit degree using the "light transmission method" — if the sealing surface fits evenly without light-transmitting gaps, it indicates that the grinding is qualified.
3. Moderate to Severe Wear: Repair in Three Steps: Turning - Surfacing - Precision Machining
If the gate valve wear is relatively serious with obvious grooves or local deformations, it needs to be repaired in three steps: Step 1: Turning — completely remove the wear layer and fatigue layer to ensure a flat machined surface; Step 2: Surfacing — select welding electrodes compatible with the valve body material. For example, A102/A022 electrodes are used for stainless steel gate valves, and nickel-based electrodes are used for cast iron gate valves. Perform surfacing with argon arc welding, controlling the current between 80 and 120 amps and the interpass temperature not exceeding 150°C to avoid welding cracks; Step 3: Precision Machining — after surfacing, first turn and then grind to ensure the dimensional accuracy and flatness of the sealing surface. Finally, perform grinding and polishing to restore the gate valve's sealing performance.
4. Key Repair Notes + Daily Maintenance Suggestions
Three key points must be kept in mind during the entire repair process: First, before repair, thoroughly clean oil stains, rust, and impurities on the sealing surface, and firmly fix the valve body to prevent deformation during repair; Second, after surfacing, stress relief heat treatment must be performed, such as tempering at a temperature of 550 to 650°C for 1 to 2 hours to eliminate welding internal stress; Third, after repair, a hydrostatic sealing test should be conducted, applying pressure 1.1 times the nominal pressure of the valve and maintaining it for 15 to 30 minutes. No obvious leakage indicates qualification.
In addition, during daily use, strengthen medium filtration to reduce impurities; open and close the valve gently, avoiding forced opening and closing. This can effectively extend the service life of the sealing surface and reduce the number of repairs.
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