First distinguish leakage through the closed valve from leakage to the environment at a flange, shaft seal or body. These conditions require different investigation paths. Installing a harder seat or applying more closing force is not a universal remedy.
Make the situation safe before investigating
Leaks involving toxic, flammable, corrosive or hot fluids must be handled by trained personnel under site emergency procedures. Do not approach a jet to locate a leak, or attempt live disassembly, tightening or actuator adjustment. Maintenance requires process isolation, depressurization, draining, any necessary decontamination, temperature confirmation and control of electrical, pneumatic or spring energy.
Separate symptoms and the information needed
| Observation | Information to verify | Technical discussion |
|---|---|---|
| Flow continues downstream after closure | Detection method, upstream and downstream pressure, flow direction, mechanical travel and process changes | Check seating conditions, debris and the agreed shutoff duty |
| External leakage at a flange | Facing, gasket specification, alignment, support and tightening records | Check the actual joint design; adding a gasket is not a universal solution |
| Leakage at the shaft or stem | Packing or shaft-seal design, wear, thermal cycling and maintenance history | Use the product-specific adjustment or replacement procedure |
| Actuator alarm or incomplete travel | Power or air supply, travel, coupling and the timing of the fault | Distinguish drive faults from mechanical resistance; do not blindly raise protection limits |
Replace vague zero-leakage claims with testable requirements
Specify the test standard and edition, test medium, differential or test pressure, direction, duration, detection method and allowable leakage. Seat testing, shell testing and verification in the installed process are different tasks. Neither a soft-seat nor a metal-seat label guarantees leak-free operation at every temperature and differential pressure.
Send a complete quotation or service enquiry
- Valve and actuator nameplates, size, identification and supply records.
- Fluid and physical state, temperature, upstream and downstream pressures, and normal flow direction.
- Leak location and when it appeared: initial startup, later operation, cleaning, switching or maintenance.
- Available test and maintenance records. Do not invent a leakage rate where it has not been measured.
Compare the actual sealing duty before changing valve type
The three-piece forged metal-seated ball valve is a product discussion starting point, not a generic cure for every leakage problem. Verify the quoted configuration and acceptance conditions before replacing another valve.
See the replacement purchasing checklist or return to the engineering selection and technical Q&A hub.
Frequently asked questions
Why can a valve leak internally even when the closed-position signal is normal?
A position signal reflects its sensing arrangement, not necessarily correct seating of the disc or plug. Under the approved safe procedure, check mechanical travel, drive connections, trapped debris and the condition of the sealing parts.
Will a metal-seated valve eliminate all leakage?
Not necessarily. Agree the test standard, medium, pressure, direction, duration and allowable leakage. Actual results also depend on manufacture, installation, wear and operating conditions.
Should I tighten every bolt immediately after finding a leak?
No. Follow the site response procedure and control the hazard first. Maintenance requires isolation, depressurization, draining and any necessary decontamination. Qualified personnel must use the tightening method specified for that product, not blind live tightening or excessive loading.
References and limits of this guide
This is a purchasing checklist, not a product-specific installation manual or dimensional drawing. The agreed standard editions, project requirements and supplied valve documents govern. Other manufacturers’ manuals illustrate general checks only; their dimensions, ratings and installation details must not be assigned to Tekron products.