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Leak Detection and Repair

The traditional operations approach to identifying air quality emissions is called the LDAR process for Leak Detection and Repair.  Leaking equipment, such as valves, pumps, and connectors, are a large source of emissions of volatile organic compounds (VOCs) and volatile hazardous air pollutants (VHAPs).1

The Leak Detection and Repair: A Best Practices Guide – is intended for use by regulated entities, such as petroleum refineries and chemical manufacturing facilities, as well as compliance inspectors. The guide details some of the problems identified with leak detection and repair (LDAR) programs. It focuses on Method 21 requirements, and describes the practices that can be used to increase the effectiveness of an LDAR program.1 

Implementation of an effective Leak Detection and Repair (LDAR) program allows facilities to control emissions that may stem from equipment leaks.2

The EPA defines LDAR as: “…a work practice designed to identify leaking equipment so that emissions can be reduced through repairs. A component that is subject to LDAR requirements must be monitored at specified, regular intervals to determine whether or not it is leaking. Any leaking component must then be repaired or replaced within a specified time frame.”2

A Leak Detection and Repair (LDAR) program following best practices will be comprised of at least six phases. A facility should complete these phases on an ongoing basis, though the frequency and timing of each individual phase will vary depending on components in use, national or regional regulatory requirements, changes to equipment, and a range of other factors.2

1. Identify Components:  Every regulated component should be physically tagged with a unique ID number. This number should be recorded on a Piping and Instrumentation Diagram (P&I Diagram), along with details of any exempt components. An equipment log or site plot plan must also be updated after any component changes. Facilities should have an appropriate procedure in place to update records where new equipment is installed, components are replaced, or specific parts are retired.2

2. Define Potential Leaks: The lowest leak definition should be used in facilities where there are multiple regulations or components. This is considered to be the best practice, simplifying monitoring while reducing any potential for confusion. This approach will also ensure a sufficient margin of safety for workers monitoring components and those working closest to any potential emissions. Should contractors or workers be confused over which regulations apply, and utilize an incorrect leak definition for a specific component, leaks could persist and fail to be reported for repairs. It is recommended that facilities check with current regulations to ensure that the correct leak definitions are being used.2

3. Monitor Components: The use of an electronic and automatic data logger will not only save time but will also improve accuracy and ensure that an appropriate audit record is provided. An LDAR program should be periodically audited to ensure that all components are being monitored. This approach will also ensure that appropriate procedures are properly followed and that all necessary records are maintained. Regular monitoring and quality checks of LDAR data are essential if a program is to continue to provide complete, accurate, and consistent results. In some instances, inspectors have exposed workers who seemed to cut corners on monitoring procedures.2

4. Repair Components: Facilities should develop an appropriate protocol and timetable for the repair of components. Ideally, a repair should be attempted as soon as possible, following the detection of a leak. The installation of ‘leakless’ valves and ‘sealless’ components may help reduce future fugitive emissions, reducing the need for ongoing repairs. When components are repaired, it is prudent to increase the frequency at which they are monitored in order to confirm that the repair was successful and that the leak has been stopped.2

5. Keep Consistent Records: Internal and third-party audits of LDAR records should be completed on a regular basis. This will help ensure that workers are properly monitoring all regulated components. The use of databases and electronic monitoring will improve the quality of audits and maintenance of records without the need to manually sift through paperwork. A robust auditing protocol will also include regular inquiries around new or revised regulatory requirements. Overall, greater problems will arise should leaks not be repaired and reported as repaired in a timely manner or where these are incorrectly recorded on a delay of repair list.2

6. Continuous Improvement: Regularly reviewing and updating records and written protocols are essential in the maintenance of an effective LDAR program. This process should start with an audit of identified components, and this audit should be compared with current P&I diagrams and any alterations to components or equipment. Protocols for a written LDAR program should be reviewed and updated, and monitoring data should be audited. New portable detecting instruments should be purchased as appropriate, and it is recommended to use calibration devices that can automatically calibrate multiple detecting instruments. An appropriate training program should also be in place for all workers or contractors. It is important to maintain regular contact with regulatory agencies or industry associations in order to keep up to date on existing or new compliance requirements that may require internal leak definitions to be adjusted.2

  1. Environmental Protection Agency (EPA), 2016, December 11, Leak detection and repair: A best practices guide, (accessed March 27, 2021).
  2. Thermo Fisher Scientific, 2021, March 02, Leak detection and repair (ldar): A comprehensive introduction, (accessed March 27, 2021).