The core causes of internal leakage in globe valves focus on sealing surface damage, component wear, or assembly deviation. These can be specifically categorized into five types, requiring targeted inspection in daily operations.

1. Sealing Surface Damage: The Most Direct Cause of Internal Leakage

The sealing surface is critical for a globe valve to block medium flow, and any damage to its integrity will inevitably lead to internal leakage.

· Medium Erosion: High-speed fluid containing particles will wear the sealing surfaces of the globe valve's valve core and seat over the long term, creating scratches and damaging the fitting degree.

· Corrosive Attack: Acidic, alkaline, or oxidizing media will react with the material of the sealing surface, causing rust and spalling, which is common in chemical industry scenarios.

· Improper Operation: Applying excessive force when opening or closing the globe valve, or exerting pressure forcibly when the valve is not fully closed, will cause deformation and cracking of the sealing surface.

2. Connection Failure Between Valve Core and Valve Stem: Indirectly Causing Seal Failure

The valve core transmits operating force through the valve stem, and connection issues will prevent the globe valve's valve core from fitting the seat accurately.

· Loose Connection: Long-term vibration or torque from opening and closing will loosen the bolts and pins connecting the valve core and stem, causing the valve core to deviate from its sealing position.

· Valve Stem Deformation: If the valve stem material lacks sufficient strength or is subjected to long-term force at high temperatures, it will bend, leading the valve core to tilt and fail to make uniform contact with the seat.

3. Loose or Damaged Valve Seat: Undermining the Seal Foundation

The valve seat is the fixed base of the sealing surface, and its stability directly affects the sealing effect of the globe valve.

· Assembly Deviation: If the coaxiality between the valve seat and valve body fails to meet standards during assembly, or the sealing gasket is not fully compressed, the sealing surfaces cannot be aligned.

· High-Temperature Impact: Under high-temperature conditions, the valve seat and valve body have different thermal expansion coefficients. After long-term use, gaps will form, resulting in loosening and displacement.

4. Impurity Jamming: Preventing Sealing Surface Fitting

Pipeline impurities are an easily overlooked cause, directly affecting the fitting of the globe valve's sealing surfaces.

· Impurity Deposition: Sediment, welding slag, and other impurities accumulate between the valve core and seat, forming an "interlayer" that prevents a tight fit.

· Jamming During Closure: At the moment of closing the valve, large granular impurities are pressed into the sealing surface, causing permanent jamming.

5. Seal Aging: Natural Deterioration of Sealing Performance

The elastic seals of a globe valve will age and fail over time.

· Material Aging: Rubber, PTFE, and other seals harden and crack under harsh conditions, losing elasticity.

· Packing Wear: Long-term friction between the valve stem and stuffing box causes packing wear. Medium leaks from the packing, and part of the leakage seeps into the sealing surface, worsening internal leakage.