LDAR Fugitive Emission Survey Singapore — Optical Gas Imaging Leak Detection

What Is an LDAR Fugitive Emission Survey?

LDAR stands for Leak Detection And Repair. It is a structured, programmatic survey of the many thousands of individual components that make up a process plant — valves, flanges, connectors, pumps, compressors, pressure-relief valves and open-ended lines — carried out to find and quantify fugitive emissions: the small, unintended releases of volatile organic compounds (VOCs) and hydrocarbons that seep from seals, joints and packing while the plant is running normally.

A fugitive leak is not a burst pipe or an obvious release. It is a valve stem weeping vapour past worn packing, a flange gasket that has relaxed under thermal cycling, or a pump seal passing a trace of process fluid to atmosphere. Individually each leak is tiny; collectively, across a refinery or petrochemical complex with tens of thousands of sealed connections, they add up to a material loss of product and a significant environmental emission. LDAR exists to find those leaks systematically rather than by chance.

The programme does more than detect. Each leaking component is identified, tagged and logged in a leak register with its location, leak indication and, where required, a measured concentration. That register is then tracked through to repair and re-survey, closing the loop that gives Leak Detection And Repair its name. The output is a defensible, auditable record that a component was found leaking, actioned and confirmed fixed — which is exactly what both regulators and plant managers want to see.

Why LDAR Matters for Singapore's Process Plants

Singapore is one of the world's major refining and petrochemical hubs, and the concentration of process plant on Jurong Island means an enormous population of sealed components — each one a potential fugitive emission source. A single large process unit can contain many thousands of valves and flanges; a whole site runs into the hundreds of thousands. Even a low percentage of leaking components across that base represents a substantial release of VOCs and lost hydrocarbon product.

Fugitive emissions matter on three fronts at once. They are an environmental-compliance issue: Singapore's National Environment Agency (NEA) regulates VOC emissions from industrial installations, and fugitive component leaks form a large, often under-measured part of a site's total footprint. They are a safety issue: escaping hydrocarbons create local flammable atmospheres and, in the case of toxic species, a personnel exposure risk. And they are a commercial issue: every kilogram of product leaking to atmosphere is product that was paid for and never sold.

This is what makes LDAR unusually attractive as a survey. Unlike many compliance activities that are pure cost, a well-run LDAR programme frequently pays for itself through recovered product — the value of the hydrocarbon no longer being lost once leaking components are repaired. It satisfies the regulator and improves the plant's margin at the same time.

The Technology: Optical Gas Imaging

The core of a modern LDAR survey is optical gas imaging (OGI). An OGI camera is an infrared imager whose detector is tuned to the specific wavelength band where hydrocarbon molecules absorb infrared energy — typically the mid-wave region around the carbon-hydrogen bond absorption. When a hydrocarbon gas escapes in front of the camera, it absorbs infrared radiation at that wavelength and appears on the display as a visible plume of moving "smoke" against the background, rising directly from the component that is leaking.

The power of OGI is that it turns an invisible problem into a picture. Instead of touching a probe to thousands of individual joints one by one, a surveyor scans a whole rack of components and instantly sees which one is releasing. It pinpoints the leaking valve, flange or seal in seconds and provides a video record of the leak that is far more intuitive to review than a column of numbers.

Where a quantity is needed — for example to grade a leak against a threshold — OGI is combined with contact or sniffer sensors in the style of US EPA Method 21, which measures the concentration at the leak interface in parts per million. OGI finds and locates the leak visually; the sniffer puts a number on it where the programme requires one. Mounting the OGI camera on a drone extends this reach to elevated pipe racks, flare tips and structures that would otherwise need scaffold, a man-lift or work-at-height access — screening them quickly and safely from a standoff position.

How an LDAR Survey Runs

A credible fugitive emission survey is a defined sequence, not an ad-hoc walk-around. Each stage builds the record that makes the result auditable.

The final deliverable is a leak report and register that a plant's environmental and maintenance teams can act on directly: what is leaking, where it is, how badly, and what needs repairing first — with the imagery and readings behind every entry.

Standards and Frameworks

Our surveys are structured around the recognised references for fugitive emission work, so the data package aligns with what regulators and auditors expect.

• NEA VOC emissions requirements — Singapore's National Environment Agency regulates VOC emissions from industrial installations; a documented LDAR programme provides evidence that fugitive sources are being detected and controlled.
• EN 17628:2022 — the European standard on fugitive and diffuse emissions of common concern to industry sectors, which sets out OGI and other measurement methodologies for quantifying component leaks.
• US EPA Method 21 — the reference procedure for determining VOC leaks from process equipment by portable instrument, widely used to quantify and grade individual component leaks.
• US EPA OOOOa (Quad Oa) — reference practice establishing OGI as an accepted method for periodic fugitive emission monitoring across facility components.

Citing these frameworks keeps the survey defensible: the methodology is not improvised, and every leak call can be traced to an accepted detection and quantification practice.

Components We Survey

A fugitive emission survey screens every accessible leak path in the process line. These are the component classes that dominate a plant's fugitive footprint and the focus of our OGI screening.

Where LDAR Fits in Your Emissions Programme

LDAR is an online survey — it is carried out while the plant is live and under pressure, because a component has to be in service for a leak to be present and detectable. That makes it complementary to, rather than dependent on, a turnaround. It runs alongside routine operations and needs no interruption to production, unlike inspections that wait for a plant shutdown.

Component-level OGI screening also dovetails with the wider emissions and integrity picture. The same optical gas imaging capability applies to flares and tank seals, where escaping vapour signals incomplete combustion or a failing floating-roof seal, and it sits naturally within a broader programme of oil and gas drone inspection and refinery inspection. Where a leak points to corrosion or mechanical loss of containment, the survey connects to tank inspection and thermal drone inspection for follow-up, and the whole activity forms part of the industrial drone inspection scope we deliver across Jurong Island plants.

Why Choose SG Drone Inspections

We are a specialist drone inspection provider in Singapore delivering optical-gas-imaging fugitive emission surveys that stand up to both regulatory scrutiny and operational use.

Frequently Asked Questions