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Running, bubbling, dripping, and leaking of valves
Valve "running, bubbling, dripping, and leaking" are common fault phenomena in industrial equipment, which not only waste resources and pollute the environment, but may also cause safety accidents.
1. Definition and manifestation
Running
Definition: Material (liquid or gas) overflows from a container, pipe or valve in large quantities.
Cause: Pipeline rupture, valve failure, overpressure or operating error leading to loss of control of the medium.
Case: For example, a damaged steam pipe valve causes high-temperature steam to gush out.
Bubbling
Definition: Liquid or gas overflows from the top of a container or equipment.
Cause: Improper liquid level control (such as overflowing storage tanks), equipment overpressure or safety valve failure.
Case: The air inlet valve is not closed during stirring of the reactor, causing liquid to bubble out of the manhole.
Dripping
Definition: Liquid slowly seeps out of the interface of the equipment or pipeline.
Cause: Wear of the sealing surface, aging of the gasket, loose threaded connection.
Case: Tiny gaps appear in the flange gasket due to corrosion, resulting in oil droplet leakage.
Leakage
Definition: The medium continues to flow out from the cracks and pores of the valve or pipeline.
Causes: Valve body defects, weld cracks, packing failure or improper operation.
Case: The valve packing was not replaced due to long-term wear, resulting in natural gas leakage.
2. Common causes
(1) Equipment factors
The valve material does not meet the standards (such as sand holes in cast iron parts).
The sealing surface is worn or the processing accuracy is insufficient.
The packing is aged, the gland is loose or the selection is improper.
(2) Operational factors
The valve is not completely closed or closed too quickly, resulting in damage to the sealing surface.
Overpressure operation causes deformation of the valve or pipeline.
Lack of regular maintenance (such as failure to clean up rust and impurities in the pipeline).
(3) Environmental factors
Low temperature cracking (such as failure to drain water from the valve in winter).
Medium corrosion (such as acidic gas erosion of the valve body).
3. Solutions
(1) Preventive measures
Strict quality inspection:
The valve is subjected to a water pressure test before entering the factory to ensure that there are no casting defects.
Standard installation:
Flange gaskets should be selected as needed (metal spiral wound gaskets for high pressure, asbestos or rubber gaskets for low pressure).
Tighten bolts symmetrically to avoid flange deflection.
Regular maintenance:
Clean impurities inside the valve (such as iron oxide and sand).
Check the packing status and replace aging packing in time.
Insulation and antifreeze:
Insulate the valve or drain the accumulated water in low temperature environment.
(2) Leakage treatment
Valve body leakage: Replace valve bodies with sand holes or cracks, and repair defective welds.
Avoid hitting the valve, and large-diameter valves need to be equipped with brackets.
Padding leakage: Replace corrosion-resistant and high-pressure resistant packing (such as PTFE).
Adjust the gland pre-tightening clearance (usually keep more than 5mm).
Sealing surface leakage: Re-grind the sealing surface to ensure the continuity of the contact line.
Replace damaged sealing gaskets and clean impurities on the sealing surface.
Operational leakage: Avoid opening and closing the valve with excessive force. After fully opening, turn the handwheel back a little.
For corrosive media, corrosion-resistant materials (such as Hastelloy) should be selected.
4. Management suggestions
(1) Establish an inspection system: regularly check the valve status and record the leakage points.
(2) Train operators: standardize the valve switching action to avoid misoperation.
(3) Use intelligent monitoring: install sensors on key valves to monitor leakage in real time.