Valve leakage is a common issue in industrial production and pipeline systems. It can cause resource waste, pollution, and even safety incidents. Below are the typical causes and solutions for valve leakage, divided into internal leakage (when the valve does not close tightly) and external leakage (when the valve body or its connections leak).

I. Valve leakage (not appropriately closed)

analysis of causes ：
Seal face damage
▷ Particulate matter in the medium washes the sealing surface (such as sand particles, welding slag).
▷ Corrosion or chemical erosion causes damage to the sealing surface (e.g., acid medium).
Seal aging or wear
▷ Rubber, PTFE and other soft sealing materials aging, cracking.
▷ Metal seal surface due to long-term friction wear.
The valve is not completely closed.
▷ Insufficient operating torque ( handwheel is not tightened, actuator is faulty).
▷ Valve stem thread or transmission parts are blocked.
Impurities stuck in the valve core/valve seat.
Impurities (such as rust and scaling) in the pipeline are stuck between the sealing surfaces.
Resolvent：
Clean or repair the sealing surface: remove the valve, grind the metal sealing surface or replace the soft sealing pad.
▷ Replacement of seals, such as valve seat, valve disc seal, or O-ring.
▷ Completely close the valve: check whether the actuator (e.g., electric or pneumatic) is in place, and confirm that the manual valve is completely closed.
▷ Drain pipe: remove impurities, and install a filter in front of the valve if necessary.
▷ Choose corrosion-resistant materials: such as stainless steel valve seat or inlined valve (for corrosive media).

II. External leakage of the valve

1. Leakage at valve stem (packing leakage)
▷ Wear or aging of packing.
▷ Packing gland bolt is loose.
▷ Valve rod scratches or corrosion.
solve ：
▷ Tighten or replace the packing (be careful not to overpress the valve stem to jam).
▷ Replace the valve stem or repair surface scratches.
2. Leakage at valve body or flange connection
cause ：
▷ The pre-tightening force of the flange bolt is insufficient or loose.
▷ Damaged gaskets (such as metal winding gaskets, rubber gaskets) or wrong selection.
▷ Valve body casting defects (sand hole, crack).
solve ：
Re-tighten bolts (apply even force in diagonal order).
▷ Replace the temperature and pressure resistant gasket (such as metal gasket selected for high temperature operation).
▷ Valve body cracks can be repaired by welding (safety assessment is required), and replaced if severe.
3. Valve cover or weld leakage
cause ：
▷ Casting defects or poor welding.
▷ Stress cracking caused by temperature and pressure fluctuations.
solve ：
Stop using the valve and replace it to prevent further problems.

III. Preventive measures

♦ Regular maintenance: check the condition of packing and sealing, and replace the vulnerable parts in time.
♦ Correct operation: avoid brutal operation to cause deformation of valve stem or damage of sealing surface.
♦ Working condition matching: heat-resistant valves (such as stop valve rather than ball valve) are selected for high temperature media. Plastic-lined valves or ceramic valves are selected for corrosive media.
♦ Installation of filter: install Y-type strainers in front of valve to prevent impurities from entering.
♦ Valve pressure test: strength test and seal test shall be carried out before installation of the new valve.

IV. EMERGENCY TREATMENT

♦ If the leakage can not be stopped immediately for maintenance:
Use a sealant (such as a metal patch) to temporarily seal it.
Apply a leak-proof clamp (e.g., clamp + sealing gasket) in case of leakage.
♦ For high-risk media (toxic, flammable), the system should be isolated immediately and treated professionally.
♦ Depending on the leakage cause and valve type (gate valve, válvula de bola, butterfly valve, etc.), the solution may need to be adjusted. It is recommended to combine the specific working condition analysis.