API Publication 7105 (1997): Technical Requirements and Implementation for Fugitive Emission Control in Process Equipment

Scope and Purpose

API Publication 7105, originally issued in 1997, provides a standardized framework for the detection, measurement, and control of fugitive emissions from process equipment in petroleum refining, petrochemical, and natural gas handling facilities. The document addresses volatile organic compounds (VOCs) and other hazardous air pollutants that may escape from valves, flanges, pumps, compressors, pressure relief devices, and other piping components.

The primary objective of this publication is to define technically sound procedures for identifying leaking components, quantifying emission rates, and establishing cost-effective leak detection and repair (LDAR) programs. It serves as a reference for facility operators, environmental engineers, and regulatory bodies seeking consistent methodologies for fugitive emission management. The 1997 edition consolidates field experience from several industries and aligns with concurrent EPA regulations while accommodating site-specific operational conditions.

The scope explicitly covers both pressurized and vacuum systems, includes guidance for selecting monitoring instrumentation, and specifies leak concentration thresholds that trigger actionable repairs. Importantly, the publication does not mandate rigid compliance but offers a best-practices approach that can be voluntarily adopted or integrated into mandatory inspection programs.

Technical Requirements

API Publ 7105 establishes detailed requirements for monitoring methods, instrument calibration, leak definition, and repair verification. The core technical specifications are organized around the following elements:

Monitoring Techniques

The standard prescribes two primary monitoring approaches: direct sensor-based monitoring (using portable flame ionization detectors, photoionization detectors, or infrared cameras) and predictive emission monitoring based on component type and service history. The preferred method is direct sensor measurement with the instrument probe placed within 1 cm of the potential leak interface. A video inspection technique is also accepted for hard-to-access connectors.

Leak Concentration Thresholds

The table below summarizes the default leak concentration limits (as methane equivalent) above which a component is considered leaking and requires repair or replacement within a specified period.

Note that these thresholds may be adjusted upward if the component is in heavy liquid service or if background concentrations exceed 5% of the leak definition. The publication also provides equations for converting instrument readings from alternative calibration gases to methane equivalents.

Quality Assurance and Calibration

All monitoring instruments must be calibrated daily before use using a reference standard of methane in air (50–100% of the expected span). Calibration drift must not exceed ±10% of the calibrated value; otherwise, the instrument is taken out of service. The standard specifies that calibration challenges be performed at two concentration levels: zero and span gas. Records of all calibrations and challenges must be retained for at least five years.

Repair Verification

After a repair is attempted, the component must be re-monitored within 30 days. If the measured concentration remains above the leak definition, additional repair attempts are required. Components that cannot be repaired to below the threshold after three attempts must be scheduled for replacement, and a root cause analysis must be documented.

Implementation Highlights

Successful implementation of API Publ 7105 relies on three pillars: program management, data handling, and personnel training. The publication recommends developing a written plan that designates a program coordinator, defines component inventories by area, and assigns monitoring frequencies. Frequency tiers are suggested: quarterly for valves in gas service, semi-annually for pumps, and annually for connectors and flanges. However, frequencies can be increased or decreased based on historical leak data—a concept later known as “volume-based reclassification” used in subsequent regulatory frameworks.

Data management is a critical success factor. The standard encourages electronic record-keeping that tracks component identification, measurement readings, repair dates, and re‑monitoring results. Trend analysis of leak rates over time helps identify systemic problems such as improper gasket selection, stem packing deterioration, or incorrect assembly torque.

Training requirements include initial certification for monitoring technicians and annual refresher courses covering probe placement, instrument operation, and safety procedures. The publication advises that at least one qualified individual per shift be designated to perform immediate response monitoring during abnormal operations or after significant pressure changes.

The publication also addresses “skip period” provisions—allowing facilities to extend monitoring intervals for component populations that consistently show low leak incidence. For example, a process unit that achieves below a 2% leak rate for two consecutive quarters may be eligible for a 50% reduction in monitoring frequency. This risk-based approach reduces costs while maintaining environmental performance.

Compliance and Certification Notes

API Publication 7105 is not a consensus standard developed under ANSI procedures; it is a technical report issued by the American Petroleum Institute to disseminate industry best practices. As such, it does not carry a formal certification program. However, many regulatory jurisdictions—including parts of the United States, Canada, and the European Union—have referenced the publication in state implementation plans or operating permits as an acceptable method for demonstrating compliance with fugitive emission regulations.

Facilities that voluntarily adopt the publication should document their implementation steps, including the written plan, training records, instrument calibration logs, and repair records. In the event of an audit or regulatory inspection, these documents serve as evidence of a rigorous LDAR program consistent with recognized industry practices.

Important considerations for compliance:

• Regulatory equivalence: Where national regulations differ from API Publ 7105 thresholds (e.g., EPA’s NSPS Subpart OOOO or the EU’s Industrial Emissions Directive), operators must apply the more stringent requirement unless an alternative equivalent plan is approved.
• Document retention: The publication recommends keeping records for at least five years. Regulatory permits may require longer periods.
• Third-party audits: Annual external audits of the LDAR program, including a review of component inventory accuracy and monitoring technique compliance, are strongly suggested to ensure program integrity.

Although the 1997 edition has not been superseded by a later revision, users should check for subsequent API bulletins or addenda that provide updated references to newer monitoring technologies (e.g., optical gas imaging cameras). The principles of the publication remain sound and continue to serve as a basis for modern LDAR standards, including ISO 17023 and the EN 15446 series.

In summary, API Publ 7105-1997 offers a technically rigorous yet flexible methodology for fugitive emission control. When implemented with discipline and supported by a culture of continuous improvement, it can deliver substantial reductions in unmitigated emissions, enhance worker safety by reducing exposure to volatile substances, and demonstrate regulatory due diligence.

Frequently Asked Questions

© 2026 International Standards Review. This article provides informational guidance. Always refer to the official API Publication 7105 for complete and authoritative language.