Valve fugitive emissions escape through an external pressure-boundary path, often around the stem, packing, bonnet or body joint. LDAR evidence should locate and trend the source before maintenance begins. The response then depends on valve design, service, condition and live-work limits.
Knowledge · Emissions and maintenance
Valve fugitive emissions: leak paths, LDAR evidence and maintenance response
How monitoring evidence becomes a controlled valve maintenance decision.
1. Separate external leakage from seat passing
Fugitive emissions leave the process boundary. A passing valve leaks internally across its seat while remaining contained within the system.
The distinction changes diagnosis and treatment. Seat sealant does not automatically address a stem leak, and external leakage does not prove damaged seats.
Common external paths include the stem packing area, bonnet joint, body joint and connected fittings. Other process components can also be the measured source.
Our live leak sealing guide explains the different valve paths and their limits.
2. Understand what the published figure means
A study reported in Chemical Engineering magazine traced 60 percent of refinery fugitive emissions to leaking valves. That figure belongs to the refinery study population reported there.
It does not establish the share for every refinery, pipeline or facility. Equipment mix, service, condition, survey method and repair history can change the distribution.
The useful lesson is not a universal percentage. Valves deserve structured attention where site evidence shows they form an important source group.
3. Treat LDAR results as evidence with limits
Leak detection and repair programmes can identify sources, record readings and track repeat findings. A single reading still needs context.
- Confirm the asset identity and exact measured location.
- Record operating state, process conditions and access limitations during screening.
- Check whether nearby equipment could affect source location.
- Repeat or confirm findings under the site's approved method where required.
- Keep repair and post-work evidence against the same asset record.
Sound, odour and visible residue can suggest an external leak. They do not replace the site's accepted confirmation method.
A per-valve service record helps connect LDAR findings with packing work, injection history and repeat leakage.
4. Match the response to the leak path
The first response may be monitoring, planned isolation or specialist live work. Severity, service hazard, access and pressure-boundary condition govern that choice.
Before any injection, the valve must have suitable fittings in good condition. Its design and service must suit the product, OEM guidance applies, and operations must permit the work.
Controlled stem treatment may be possible on suitable designs. Body or bonnet joint leakage needs separate specialist assessment because it involves the pressure boundary.
Damaged fittings, unstable leakage or uncertain source location justify stopping. Severe damage can require isolation and mechanical repair rather than online treatment.
Read the body and bonnet joint guide before treating these leaks as routine packing faults.
5. Close the repair loop with evidence
Maintenance completion and emissions reduction are not the same record. The site needs post-work evidence from its accepted monitoring method.
- Record the confirmed leak path and pre-work result.
- Record the authorised method, product and operating conditions.
- Document stop-work events or limits reached during the task.
- Repeat the accepted measurement after conditions have stabilised.
- Set monitoring and escalation triggers for any temporary repair.
An improved sound or appearance can support screening, but it does not prove the required emissions result. Use the programme's specified method.
6. Use maintenance data to improve the programme
Repeated findings can expose a pattern by valve type, service, location or previous repair. That pattern guides inspection and replacement planning.
Do not assume every repeat leak has the same cause. Packing wear, surface damage, fitting faults and operating conditions may need different responses.
Link LDAR records with valve integrity management, rather than keeping emissions work separate from asset condition. BTR VSI field services and surveys can assess suitable valves, while the operator owns LDAR acceptance.
Common questions
Valve emissions questions, answered directly
Are fugitive emissions the same as a passing valve?
No. Fugitive emissions escape through an external pressure-boundary path. A passing valve leaks internally across its seat while product remains inside the process system.
Does the 60 percent figure apply to every facility?
No. A study reported in Chemical Engineering magazine traced 60 percent of refinery fugitive emissions to leaking valves within its study context. Facility distributions can differ.
Does an LDAR reading identify the repair method?
Not by itself. Confirm the asset and leak path, then assess service, design, fitting condition and pressure-boundary risk before selecting monitoring, live work or isolation.
How should a repair be verified?
Repeat the site’s accepted emissions measurement and record it against the same asset. Sound, appearance or reduced residue can support screening, but do not prove acceptance.
Responding to a valve emission?
Send the leak evidence. An engineer replies within 24 hours.
Include valve identity, measured location, service, operating state and LDAR history.