Fugitive Emission Inspections with Acoustic Imaging | SonaVu™

SonaVu™ is a multi-frequency acoustic imaging camera that blends visual and auditory senses to bring fugitive emissions, natural gas, and oil leaks into focus.

One problem facing refineries and oil and gas (O&G) plants is how to identify and eliminate sources of leakage into the atmosphere. Fugitive emissions is an all-encompassing term used to describe both intentional and accidental leaks. This term brings our attention to finding and eradicating them. The threats imposed by fugitive emissions vary from unpleasant odors to serious, hazardous safety risks for plant personnel and populations living within the danger range of facilities.

Sources of Fugitive Emissions

There are many sources of fugitive emissions within the O&G industry segments. Sadly, many sources are intentional or, let us say, part of the process; whether that process be manufacturing, refining, transporting, venting, flaring, and storage. However, accidental sources of fugitive emissions fall under the categories of "equipment leaks" and "accidents and equipment failures>". It is within these categories where we discover the highest risk because the leaks can be both long-term or sudden and impactful.

David Picard of Clearstone Engineering Ltd, identifies five sources of fugitive emissions.

1. Equipment leaks;
2. Process Venting;
3. Evaporation losses;
4. Disposal of waste gas streams (venting/flaring);
5. Accidents and equipment failures;

Long-term leaks are usually hidden from records. We don’t know they are there, or… we do know, but aren’t really concerned about them. Worrying about long-term leaks may not be part of a job description, but industry needs to be aware of the risks and be called to action. Long term leaks should not be disregarded unless their collective contribution to total fugitive emissions is proven to be negligible. - Fugitive Emissions from Oil and Natural Gas Activities, David Picard, Clearstone Engineering Ltd.

Valves, and especially the packing which prevents leaks to atmosphere is a significant contributor. Unfortunately, many industries approach to valve maintenance is "run to failure". Without regular condition monitoring it is difficult to even realize that poorly maintained valves are a primary source of fugitive emissions.

Piping is another source of long-term leakage. Gasketing and packing around flanged couplers, corrosion, poor workmanship, and worn connectors are primary culprits. Additionally, compressor seals, pressure relief devices, and process drains should be considered as additional sources of fugitive emissions.

Methods for the Detection of Fugitive Emissions

There are numerous methods for detection of fugitive emissions including ambient air monitoring, gas sniffing, ultrasound, and ultrasound acoustic imaging cameras.

Ambient air monitoring samples air quality around the vicinity of a complex. The sensing of methane (CH⁴), carbon dioxide (CO²), and even nitrous oxide (N²O) reveals that fugitive emissions are a problem, and the need for detection and repair is a must. Ambient air monitoring alerts organizations about the problem, however, it does not solve it.

Gas sniffing involves the use of detection instruments that sense the presence of a certain gas type, and then quantifies its severity in terms of parts per million (PPM). Gas sniffers are not an exact science as their effectiveness is affected by wind and humidity. Their sensors may reach a saturation point in the case of severe fugitive emissions in which case their usefulness is called into question.

Ultrasound works well in most environments, so far as the leak has a differential pressure that produces turbulence. Laminar leaks are not detectable with ultrasound. However, most gas leaks do involve movement of the gas from the high pressure to the low-pressure side. The turbulence at the leak site has peaks at 40kHz – the working range of SDT Ultrasound instruments.

These sophisticated instruments are highly sensitive, can detect the source of gas leaks from safe distances (where necessary), are not impacted by wind, and are relatively low cost. Moreover, the use of ultrasound instruments comes with a low competency curve. New inspectors can be onboarded in just a few hours of training. SDT ultrasound instruments have many other uses in addition to the detection of fugitive emissions.

• Mechanical condition monitoring
• Bearing lubrication guidance
• Compressed air leak detection
• Steam trap assessment
• Electrical fault detection
• Valve assessment
• Detection of cavitation
• Analysis of gearboxes

SonaVu™ from SDT Ultrasound Solutions, is a new technology that shows promise for the detection of fugitive emissions within the oil and gas and refining verticals. SonaVu™ is a multi-frequency acoustic imaging camera that blends visual and auditory senses to bring fugitive emissions into focus.

Each SonaVu™ comes equipped with 112 highly sensitive ultrasonic microphones that form a wide field of detection. That same field of detection is brought into view through a precision optical camera. Inspectors with SonaVu™ in hand can hear and see every leak simultaneously through an audio output and on the large, 5” color display.

With SonaVu™ from SDT finding, documenting, and repairing fugitive emissions, natural gas, and oil leaks has never been easier. SonaVu™ brings the power of superhuman hearing to focus on its vibrant color screen. Most fugitive emissions remain inaudible and invisible to humans. Detection attempts are further stymied by the rumble and roar of the factory environment. But SonaVu™ is tuned to hear only the ultrasonic component created by turbulence at the leak site. At the same time, it remains impervious to the noise of production. Fugitive emission detection and management projects can be conducted at the height of production regardless of background noise.

Leak Finding Procedure

A simple leak detection procedure consists of picking up the SonaVu™ and powering it on. Connect the high-quality noise attenuating headphones so you can hear what SonaVu™ hears. Then simply point the acoustic sensor array towards any potential sources of fugitive emissions. Listen for the characteristic hissing of the leaks in the headphones and watch the color display light up with the precise location of the leak.

All controls are found on the SonaVu™ touch screen.

1. Set the distance:
   • Choose near range (<1m) or far range (>1m) or auto range to let SonaVu™ decide.
2. Set the frequency:
   • For compressed air leaks choose 35-40kHz
3. Set the gain:
   • Difference between min/max sound pressure.

Each source of fugitive emissions must be documented to follow up the repair. Leaks are documented in pictures. Choose to create a still image (camera icon) or a video (video icon) for generating leak survey reports. SonaVu™ saves the leak image in either photo or video format. Download your leak survey and produce actionable reports that actually get those leaks fixed.

Change the Culture of Environmental Sustainability

Your organizational culture dictates the overall success of any maintenance strategy. Fugitive emissions represent a real threat to safety and the environment. Whether small or large, these leaks contribute to greenhouse gas emissions as well as the health and safety of personnel and civilians living within proximity of refineries and oil and gas complexes.

Having trouble getting buy-in from management to tackle the risks associated with fugitive emissions? Contact SDT to discover strategies that educate every stakeholder and empower them to take action. When it comes to ways to eliminate bottom line costs and protect the environment, fugitive emission projects must be considered high priority. SonaVu™ from SDT provides an opportunity to capitalize by eliminating risks from multiple sources.

SonaVu™, the world’s favourite ultrasound company. If you are going to buy an ultrasonic acoustic imaging camera for finding fugitive emissions, natural gas, and oil leaks, doesn’t it just make sense to choose one from an ultrasound company?

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