New technology is making it easier to detect shipboard gas leaks, reducing the risk of fire and improving safety for seafarers
The risk of gas leaks on board tankers was thrown into the spotlight recently following a high-profile incident in California late last year.
Long Beach harbour, where residents' complaints of a strong smell, headaches and nausea were traced to fugitive emissions from a VLCC (credit: Ron Reiring/flickr)
In November 2018, residents of Long Beach reported headaches and nausea and a strong petroleum smell, which local authorities managed to trace to a crude oil tanker berthed in the city’s harbour.
Inspectors from the South Coast Air Quality Management District (SCAQMD) issued a Notice of Violation for fugitive emissions to GAS North America, the shipping agent responsible for the Hong Kong-flagged Nave Photon VLCC.
Using portable hydrocarbon detection devices and gas-imaging cameras, the inspectors found seven out of 10 inspected pressure release devices were leaking hydrocarbon vapours in excess of limits set out by the agency.
Gas detection technology needs to be current, fit-for-purpose and well maintained; the consequences of a lapse in any of these three criteria could be costly or potentially lethal. IMO brought in Regulation XI-1/7 in 2016, requiring SOLAS-applicable vessels to carry portable gas detectors to monitor enclosed spaces, stating: “As a minimum, these shall be capable of measuring concentrations of oxygen, flammable gases or vapours, hydrogen sulphide and carbon monoxide.”
It is essential that owners keep up with the latest measures and technology, discussed below, to ensure the safety of crew and the general population alike.
Mesh networks detect leaks
Arild Saele (ScanReach): Facilitating the wirelessly tracking of crew inside a vessel
Straume, Norway-based Scandinavian Reach Technologies (Scanreach) has developed a connectivity solution specifically tailored for the challenges of the maritime environment.
ScanReach’s In:Range system was developed to answer the question “Why can’t we wirelessly track people inside a vessel?”, says chief executive Arild Saele.
The In:Range system is based around wearable sensors in a mesh network, eliminating the need for extensive cabling networks traditionally used for data transfer in large, complex steel environments like ships.
As well as providing accurate location data, ScanReach’s wearables can incorporate gas detectors and temperature sensors, providing information about the environment in which they find themselves.
ScanReach also offers the In:Connect system, a network comprising interior and exterior sensors and a central data processing unit. The sensors can be installed on board existing equipment and can link to third-party sensors. Features such as temperature sensors and gas detectors mean that in the event of an incident such as a gas leak or fire, information can be accessed about where the most dangerous areas are. Information can be streamed directly to the vessel’s bridge, as well as onshore operations centres or other parties.
ScanReach’s offerings can be integrated with digital platforms Kognifai from Kongsberg and Veracity from DNV GL, as well as customers’ own cloud computing systems.
Successful pilots of the technology have taken place on a Norwegian coast guard vessel, the large trawler Atlantic Star, and offshore support vessel North Sea Giant. The technology is set to launch at Nor Shipping in June this year.
"Gas detection technology needs to be current, fit-for-purpose and well maintained; the consequences of a lapse in any of these three criteria could be costly or potentially lethal"
Long-range gas detection
Most gas have infrared absorption characteristics that mean they can be targeted with cameras using infrared thermography.
Unlike laser detectors, or so-called ‘sniffers’, this technology does not require the operator to be in close proximity to the leak, increasing safety and making it easier to monitor for leaks across a broader area.
Wilsonville, Oregon-based FLIR Systems has recently announced the launch of its first uncooled methane-gas detection camera, the GF77 Gas Find IR.
The handheld camera is designed to offer a roughly half price alternative to cooled gas inspection thermal cameras and is based on the FLIR T-Series camera platform.
Spectral targeting improves visualisation and reduces false readings from gases that absorb in other wavelengths, says the company. The GF77 also incorporates laser-assisted autofocus to aid in targeting leaks, and a one-touch contrast improvement to make gases stand out more clearly.
FLIR Systems’ president and chief executive Jim Cannon says: “The FLIR GF77 Gas Find IR gas detection camera is built around an uncooled, longwave infrared detector, which costs less to produce than our higher performance, cooled cameras.”
CO2 leaks may hinder fire systems
ABS has called on shipowners to conduct risk assessments of fixed fire systems, following multiple instances of CO2 cylinders in such systems being found to be empty. The class society has been joined in such calls by the Italian Coastguard - which sent a letter to major shipowners supporting ABS’ assessment and calling for risk assessments to be undertaken - and Italy’s Ministry of Infrastructure and Transport, which has called for: “A specific and documented risk assessment, aimed at outlining any necessary measures to protect workers' safety and health.”
Traditionally, inspection of CO2 cylinders in such systems would involve them being dismantled, weighed, and reinstalled – a difficult operation that requires two people and takes approximately 15 minutes. Another option is the use of pressure gauges: it is assumed that when some of the contents of a pressurised container are discharged, the internal pressure will decrease. But this internal pressure is dependent on the temperature of the agent, which can be difficult to account for, thereby potential giving inaccurate results.
Ultrasound-based measuring technology, such as the Portalevel system offered by UK-based Coltraco Ultrasonics, is an alternative to these traditional methods. Rather than measuring pressure, it measures the liquid level. Coltraco also offers a PortaSteele product range that can concert liquid levels obtained by the Portalevel system into an exact fill-weight for the agent inside a cylinder, with built-in datalogging capability. The company says this offers time and labour savings over traditional methods, as it does not require the unit to be deactivated, disassembled and then reassembled whenever weighing is carried out. Requiring just one person to operate, it can take as little as 30 seconds per cylinder to identify a leak, according to the company.
Cambridgeshire, UK-based Ion Science specialises in photoionisation detection (PID) technology. Late last year it released the Sensor Development Kit, which integrates the company’s MiniPID sensors into existing products across a range of applications.
Utilising patented Fence Electrode Technology, Ion Science’s MiniPID 2 sensors are resistant to humidity and contamination from moisture, dust and aerosols, making them suitable for the detection of volatile organic compounds (VOCs) across a range of environments, says the company. The MiniPID 2 is available in the following models, suitable for detection at varying ranges: 0-3 parts per million (ppm); 0-40 ppm, 0-100 ppm with a 10.0 electron value output; 0-100 ppm with an 11.7 eV output; and 0-6,000 ppm. All of the MiniPID sensors are available with a choice of three different safety ratings of varying voltage, with a trade-off between longer lamp lifetimes at lower voltages and increased sensitivity at higher voltages.
Developed in response to the increasing demand for measurement of VOCs, the SDK is intended to allow original equipment manufacturers (OEM) to integrate the MiniPID sensor range into existing systems at a low cost.
The small size of the SDK and the number of available interfaces means MiniPID sensors can be easily integrated into existing systems and applications that require PID detectors as a low-cost alternative to fixed and portable gas detection systems.
Ion Science managing director Duncan Johns explained: “For OEMs and systems integrators, the Ion Science Sensor Development Kit is the simplest, quickest and most flexible way to incorporate VOC monitoring into new and existing gas detection applications.”
‘Bump It’ campaign
Since April 2018, the British Safety Industry Federation (BSIF) has been running a “Bump It” campaign, to increase awareness of the need to ‘bump test’ gas monitors whenever they are used.
Existing recommendations state gas detectors undergo servicing and a full calibration at least once a year, but BSIF makes the point that only establishes that the sensor was working correctly at that particular time; through day-to-day use there are many reasons why the sensor could lose responsiveness or develop problems between tests.
A bump test involves exposing the instrument to a known concentration of test gases, ensuring that sensors detect the gas and that readings are accurate. No calibration adjustments are required unless readings taken in such a test are found to be inaccurate. Such tests are estimated to take between 15-20 seconds per instrument, BSIF says, and the costs of sample gases used for this kind of testing are negligible. Failure to test and document the performance of such monitors however could leave employers exposed to liability in the event of an accident and increase the risk of accidents. It is therefore recommended that such tests are carried out and their results recorded before and after each time a detector used.
Gas detector supplier GfG Gas Detection UK’s sales manager Julian Butler points out that most gas detector manufacturers now offer docking stations that not only automatically calibrate instruments, but also conduct bump tests and store calibration records. The price of such equipment is also falling: “In the past, it might take a large quantity of instruments to justify the expense of investing in a docking station,” said Mr Butler, “but as prices continue to drop, customers with only a few instruments are finding that investing in an automatic calibration station makes very good sense.”