Answered July 28 2019
Leak detection and repair (LDAR) refers to U.S. Environmental Protection Agency regulations designed to help reduce volatile organic compounds (VOC) and volatile hazardous air pollutants (VHAP). Current regulatory programs require that companies, especially those in petroleum and chemical industries, follow strict LDAR compliance procedures.
Its purpose is to reduce and eliminate unintended emissions of liquids and gases. This practice is essential for plants that work with oil, gas, and chemicals. These companies are required by law to implement a thorough LDAR program.
LDAR is particularly concerned with volatile organic compounds (VOC) and volatile hazardous air pollutants (VHAP). By identifying and repairing leaks, companies can promote safety in the workplace, while reducing product losses. These processes can also contribute to environmental efforts by mitigating the release of harmful substances.
Specific steps on implementing an LDAR program may be specific to each company. Likewise, government regulations will vary across states. Whatever the circumstances are, LDAR programs have five elements in common. The next sections will discuss some of these in more detail.
Each component under the program is identified and assigned an ID. Its corresponding physical location is verified as well. As a best practice, components can be tracked using a barcoding system to be more accurately integrated with the CMMS.
The parameters that define a leak should be clearly understood by relevant personnel. Definitions and thresholds must be well documented and communicated across the teams.
Each identified component should be routinely monitored for signs of leaks. The frequency of checking, also called the monitoring interval, should be set accordingly.
Leaking components should be repaired within a set amount of time. The first repair attempt is ideally done within 5 days after the leak is detected. For delayed repair work due to any planned downtime, a documented explanation should be provided.
All tasks and activities that are performed and scheduled are recorded. Updating the activity status on the CMMS helps to keep track.
The kinds of leaks that LDAR identifies can be more subtle than the household pipe leak that the average person commonly encounters. Leaks that contain VOCs and VHAPs involve gases that are harder to visually recognize. Because of this, LDAR uses detection instruments that are sensitive enough to measure gas concentrations in areas surrounding a component. Leaks are measured in parts per million (ppm), as most standards set limits in ppm.
A leak refers to any detection of concentration levels above a standard threshold. Thresholds differ according to the regulation being observed, the type of component concerned, as well as the type of fluid being measured.
For example, most standards set by the National Society of Professional Surveyors (NSPS) define leaks to be greater than 10,000 ppm. On the other hand, the National Emission Standards for Hazardous Air Pollutants (NESHAP) commonly set leak definition standards at 500 ppm or 1,000 ppm.
While leaks that are mostly expected in small quantities are harder to detect during ocular inspections alone, visual reporting is still a common practice. Observations of fluids dripping, spraying, or misting all point to a probable leak source. Other unusual sounds and smells are also possible indicators of leaks. These sensory inspections are considered as other practical methods of detecting leaks around the plant.
Some types of equipment are more common culprits than others. Uncontrolled VOC emissions at a typical facility can emit hundreds of tons per year just looking at a handful of types of equipment. Keep an eye on these common sources of equipment leaks:
Pumps are mostly either centrifugal pumps or reciprocating pumps. These devices move fluids, particularly liquids, around the plant. Leaks from pumps are usually found around the seal – the part that connects the pump to a shaft.
Valves control the passage of fluids. They regulate fluid flow by either restricting or opening the path of the fluid. Leaks typically occur at the stem of the valve. This can happen when a sealing element, such as an o-ring, becomes damaged or compromised.
Connectors refer to the joints between pipes and other equipment. These components include flanges and fittings. Fasteners like bolts usually join the parts together. A gasket goes in between components to avoid leaks. These components wear out over time, which in turn leads to a higher risk of leaking.
Think of sampling connections as more specific examples of connectors and valves. These components enable workers to draw samples within intermediate steps of a process.
Compressors increase the pressure of fluids, typically gases. Various plant processes require high pressures for movement or pneumatic applications. As with pumps, leaks from compressors usually occur at the seals.
Pressure relief devices, such as relief valves, are special safety equipment that prevent pressure levels from exceeding limits. These devices need special attention due to the safety-related nature of their application.
Open-ended lines, as the name suggests, refer to pipes or hoses that are open to the atmosphere. Components such as caps or plugs usually limit these lines. Leaks can occur at the seals, especially during improper block and bleed procedures.
The most basic method for monitoring leaks involves just the senses. Sensory inspections include using sights, sounds, and smells as practical ways to detect leaks, especially those that are easily recognizable and non-hazardous.
Other standard methods to monitor leaks include the use of detection instruments. Types of detection include catalytic oxidation, flame ionization, and infrared absorption. These instruments are calibrated to a gas of precisely known concentration to ensure accuracy.
Tools and methods become more complex for more sensitive measurements. For example, newer technology allows for optical gas imaging (OGI) to safely detect industrial gas concentrations. Among the list of substances that it can measure are methane, sulfur compounds, and other hydrocarbons.
The frequency of monitoring activities varies according to regulations and component type. Frequencies or intervals are usually weekly, monthly, quarterly, and yearly. Some regulations might require shorter intervals when dealing with specific toxic compounds.
A typical LDAR program would include a weekly walk-through inspection to look out for audio, visual, or olfactory signs of leaks throughout the plant. Components such as valves, compressors, and relief devices go through more thorough inspections monthly and quarterly. These inspections occur less frequently, but are more accurate because of the use of detection equipment. Other components that are unlikely to leak, such as connectors, undergo inspections using a detection instrument less frequently, such as every 2 years.
Results from monitoring activities directly relate to key performance indicators of your LDAR program. By this time, you would have accounted for all essential components of your plant that needs monitoring. You would also have performed all inspections and tests to comply with set standards. By keeping all the information in a repository, you can build strategies around how to maintain or improve your performance. Identify components that are exhibiting best practices and call out the parts that pose risks.
Recordkeeping equips you with the information to come up with data-driven actions. It includes details such as the date any leaks were detected, component details, attempts at repair, and results of any repair work. As a best practice, also include QA/QC inspections and audit findings.
Recordkeeping is practically done hand-in-hand with inspections. For this sort of work, it helps to maximize the features of available technology. For example, a mobile CMMS can update your component records as you go. Seemingly small improvements to the process help ease what used to be purely manual tasks.
Regulations for implementing LDAR are available at federal and state levels. These provide guidelines on how to carry out LDAR processes properly. While most of these are concerned with environmental protection, they also provide steps on how to perform LDAR accurately and safely. Here are a few examples of these programs:
While not exactly a set of regulations, the Method 21 document offers best practices on how to determine VOC leaks.
The document 40 CFR 60, within the Code of Federal Regulations, is a comprehensive set of standards. It includes subparts that provide leak performance compliance standards for the oil and gas, and chemical manufacturing industries, among others.
The TCEQ identifies the compliance standards to obtain permits, particularly for oil and gas companies. These permits, also known as air permits, prevent pollution and reduce industrial process emissions.
Facilities required to comply with LDAR must establish a system to find and fix leaks in pumps, compressors, valves, and agitators. At the very minimum, companies must establish a regular preventive maintenance program to periodically check potential leak components and complete environmental reporting procedures.
In order to comply with LDAR regulations and prepare for a potential audit of systems, affected companies must implement programs and processes to address potential and actual leaks.
All employees must be trained on the regulatory requirements and the benefits of leak monitoring and repair. This should include written guidelines about operational processes, maintenance requirements, and leak rate goals. Certain managers must be accountable for implementing the LDAR and ensuring compliance from internal technicians and external contractors.
In addition, implementing technology such as barcoding, RFID labeling, or associated computer systems could help track leak-prone equipment. These systems could also provide a complete record of problems, repairs, and maintenance activities, as well as show the frequency of leak detection diligence.
Petroleum and chemical companies can easily reduce costs, eliminate potential fines, and contribute significantly to worker safety and environmental protection through LDAR compliance programs. Industry studies show that harmful emissions can be reduced by more than 50 percent in many cases and that cost savings could be upwards of $700,000 per facility.
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