Methods of reducing methane emissions through operational repairs:
- Perform periodic leak-detection surveys.
- Repair leaks as soon as practical.
- Check that repairs have been successful.
- Keep track of repairs that have not been carried out.
- Keep and analyze records of leaks and repairs.
For routine maintenance and repairs:
- Use pumpdowns for pipelines and large vessels.
- Minimize the volume that has to be depressurized.
- Use vapor-recovery units when pigging.
- Avoid emissions by, for example, using hot taps to make connections to pipelines, carrying out non-intrusive inspections, and coordinating repairs and maintenance.
- If venting is necessary, flare the vented gases.
Operational repairs are vital for reducing methane emissions, by both repairing leaking equipment and minimizing emissions that arise during routine maintenance and repairs. This guide covers repairs to leaks discovered during inspections carried out as part of a leak detection and repair program, as well as releases that may occur because of other maintenance and repairs.
Methane emissions from equipment leaks can be reduced by the following measures:
- Keeping an accurate inventory of emissions from equipment leaks (including the duration of the leaks), and carrying out inspections as part of a leak detection and repair program (leak detection is also covered in the separate Equipment Leaks best practice guide).
- Emissions from leaks can be further reduced by:
- Making repairs as soon as reasonably practical and keeping track of any repairs that have to be delayed.
- Carrying out checks to make sure repairs have been successful.
- Keeping accurate records of leaks and repairs.
- Routinely analyzing records of leaks and repairs.
Methane emissions from routine maintenance and repairs can be reduced by the following measures.
- Planning steps to reduce venting when large vessels and pipelines need to be depressurized.
- If venting cannot be avoided, flaring the released gases.
Methods of reducing methane emissions from equipment leaks
Carrying out a leak detection and repair program
With a leak detection and repair program in place, regular inspections are carried out to find leaks and carry out repairs.
Repairing leaks as soon as reasonably practical
Making repairs as soon as reasonably practical is important in order to minimize emissions.
Keeping track of outstanding repairs
Leaks not yet repaired should be placed on a ‘delay of repair’ list. This list should show the location of the leak, the date it was discovered, an estimated date for the repair, and an explanation of why the repair was delayed.
Keeping accurate records of leaks and repairs
Each facility should maintain a record of all leaks that are discovered, the date of each repair and an explanation of the repair method, and confirmation that the repair has been successful (when this has been confirmed). The record must be detailed enough to allow future analysis of whether the same component is leaking again.
Analyzing records of leaks and repairs and taking action where necessary
Regularly analyzing information, at approximately the same frequency as your inspections to detect leaks, can identify components or types of component that persistently leak. These components should be targeted for correction or preventative maintenance.
Methods of reducing methane emissions from routine maintenance and repairs
Minimizing the volume that has to be depressurized
To reduce the internal volume of a pipeline or vessel that needs to be depressurized by releasing gas, use temporary line stops to isolate the section where repairs are needed.
Reducing emissions from pigging a pipeline by using a vapor-recovery unit to capture the released gases
Gas is vented when a pig is launched and received. Gas is also released from storage tanks receiving the liquid and debris removed by pigging. These emissions can be reduced by using a vapor-recovery unit or flaring the gases that are released.
In some cases, emissions can be avoided completely by:
- Using hot taps to make new connections to pipelines.
- Carrying out non-intrusive inspections (for example, by using pigs with sensors).
- Reducing the number of blowdowns by coordinating repairs and maintenance events into a single downtime.
Flaring vented gases, if venting cannot be avoided
If venting cannot be avoided, flaring the gas will reduce the emissions impact of a venting event.