Drone technology may be the answer to the question of how to improve safety in the tank cleaning process, while wash-water analysis could improve shipping’s environmental credentials
The risks involved in tank cleaning were brought into stark focus September 2018, when crew members on board chemical tanker Key Fighter died tragically following a tank-cleaning operation.
In the early hours of Saturday 1 September 2018, two crew members were found unconscious on board the Maltese-flagged tanker, owned by Sea Tank Chartering and managed by Fjord Shipping. An investigation later revealed the crew members had been exposed to hydrogen sulphide gas in an empty cargo tank, where they had been performing tank cleaning duties.
Other crew members attempted first aid and a rescue helicopter was called which took the two men to a hospital in Ålesund. One of the crew, a Spanish national in his 70s, died shortly after arriving at the hospital, while the other crew member, a Philippine national in his 40s, succumbed on the morning of Sunday 2 September.
The vessel berthed in Måløy, where authorities investigated the vessel and did not find any technical defects; it then continued to Erith, England. Both crew members were married with children and Fjord assisted the families in traveling to Ålesund.
A spokesman for Fjord Shipping said: “Fjord Shipping wants to express its sincere sympathies with everyone who is affected by this tragic accident…Fjord Shipping has carried out its own surveys and reviewed existing routines to ensure safety on board…However, since the formal authorities' investigations have not been completed, it will not be appropriate for the company to answer further questions at this stage.”
Confined space entries, such as those that exist to perform post-tank cleaning inspections, are widely recognised as a source of risk, and it is accepted that their use should be kept to a minimum. Still, such entrances are necessary when carrying out visual or wall-wash inspections of cargo tanks to ensure the efficacy of tank-cleaning operations prior to on-boarding a new cargo.
Unsurprising then that the industry as pushing hard to introduce new, safer methods of cleaning, inspection and analysis that could help save lives.
Drone technology has advanced quickly from quirky novelty to a key component of the industry’s toolbox and tank inspection is an area where drones can make a huge difference. August 2018 saw Scottish survey and inspection specialist Cyberhawk perform a full class inspection across 19 tanks on board an oil tanker in a Singapore shipyard, including 12 cargo oil tanks. US class society ABS was present to ensure the inspection was compliant with its specific ruleset for tankers.
Commenting on the project Cyberhawk technical director Malcolm Connolly said: “Since we conducted the first UAV tank inspection back in 2015, the take up of this solution has become increasingly adopted within the industry.
"Confined space entry has become a 'routine' operation on board chemical tankers - this is fundamentally wrong"
“These previous inspections, however, have only focused on capturing visual data of approximately 20 to 30 critical areas. To comply with ABS rules for this particular category of class survey, we required close-up coverage of 100% of the tank’s internal frame structure at a resolution equivalent to a person viewing the surface at arm’s length.”
The company previously carried out a proof-of-concept inspection with ConocoPhillips in May 2018, inspecting 19 tanks on Polar Discovery in just 16 days and returning in September the same year to undertake further inspections.
Class society DNV GL has also pioneered the use of drones for carrying out close-up surveys in a number of applications, including tank coating inspections. The first such test survey was carried out aboard an oil tanker in November 2015, and the first production drone survey was carried out aboard chemical tanker Apollo in Bremerhaven, Germany, in June 2016.
Drones offer many advantages over traditional inspection methods - such as cranes/cherry pickers and rafting - both in terms of safety and financial impact. First and foremost, they improve the safety of surveyors and other personnel, as the operator keeps their feet firmly on the ground. Financial savings are possible due to the shorter time required to prepare for close-up access, while costs associated with rafting, such as filling tanks with water, discharge of polluted water, running time for cargo pumps, are also reduced. A further benefit can be found in the flexibility of survey locations, as no access to shore facilities is required. Finally, the risk of damage to coatings from the construction of staging inside ship compartments is also eliminated.
DNV GL’s research and development department has recently confirmed that thickness measurements can be carried out using drones, and there are ongoing studies into the potential for drones to operate autonomously and be capable of automatically recognising coating and corrosion patterns.
Looking further ahead, DNV GL sees potential for surveys to be carried out entirely remotely, eliminating the need for tank entry altogether. Advances in technologies, such as virtual and augmented reality, increased connectivity and digital tools - such as those dealing with data analytics - could bring with them a range of benefits. Initially this may require human input, in the form of a crew member being directed around a tank by the surveyor, but this could ultimately lead to drones being used to carry out partial pre-scans prior to the surveyor coming on board, and even further ahead, full 3D mapping of spaces.
DNV GL believes as a consequence, surveys will become more efficient, flexible and safer. Remote survey tools could also mean vessel operations are interrupted less frequently, and data analytics could allow for new insights to be gained, leading to improved safety management.
Elsewhere in the tank cleaning sector, Nottinghamshire, UK-based chemical consultancy L & I Maritime’s director Guy Johnson has long maintained that the passing of a wall wash inspection process has no impact on whether a vessel can successfully load cargo. Indeed, he believes this process may actually put seafarers at risk.
Guy Johnson (L&I Maritime): "Washing water analysis cannot completely eliminate confined space entry, but it can significantly reduce its frequency"
Wall wash analysis involves solvent being splashed onto bulkheads inside the cargo tank, then tested to meet pre-set test specifications. But in a white paper titled Responsible Cargo Tank Cleaning – Washing Water Analysis, Mr Johnson says such inspections are effectively random, due to the impossibility of defining which specific places in a tank should be checked; they are also subjective he says, as “two different inspectors will always see the same cargo tank with very different eyes.” Therefore, Mr Johnson believes the test is not reproducible, meaning it has no legal value in the event of cargo contamination claims, unless proof of negligent action on the part of the inspector can be established.
“We required close-up coverage of 100% of the tank’s internal frame structure at a resolution equivalent to a person viewing the surface at arm’s length”
He adds that as only a small amount of the internal area is wall washed, this means the remainder of the tank is an unknown and potentially not clean.
Mr Johnson has outlined several other issues relating to the difficulty in establishing exact measurements of contamination using wall wash inspection, concluding that the method is not capable of providing reassurance that a tank is suitable for loading.
“Passing the wall wash inspection does not provide cargo interests with the one piece of information that they require, and that is a guarantee that the nominated cargo can be loaded without risk of contamination,” he says.
Instead, Mr Johnson sees wash-water analysis as being a safer, more reliable alternative to inspections carried out inside the tank. The wash-water analysis method uses UV spectroscopy to identify what is being removed from cargo tanks and coatings during the tank cleaning process itself, rather than seeing what is left behind afterward. Tank cleaning is stopped when no traces of previous cargo can be found in the washing water, as this means continued washing will not be able to make the tank any cleaner.
This method reduces both cleaning time (each sample takes less than one minute to analyse) and the use of cleaning detergents, positively impacting the environment. “For the industry as a whole, the environment wins every time,” says Mr Johnson.
There are also safety benefits to this method. Mr Johnson says that multiple cargo tank entry during tank cleaning operations on board a tanker only occurs to ensure compliance with the pre-loading inspection specifications for the next nominated cargo. Regardless of whether these specifications are for a visual inspection or wall wash, the cargo tanks still have to be entered.
“Every time a cargo tank is inspected, at least one man has to enter a confined space, which is recognised as being one of the most hazardous operations in the entire chemical tanker business.
“This means that confined space entry has become a “routine” operation on board chemical tankers today - this is fundamentally wrong.
“Washing-water analysis cannot completely eliminate confined space entry, but it can significantly reduce its frequency and even saving one confined space entry is a step in the right direction.”
Discussing the response this wash-water analysis has met from the industry, Mr Johnson says: “Generally the response has been positive, but it is clear that different cargo interests have different requirements and the reason the wall wash inspection still dominates the business is because commercial interests are in charge; sadly (in my opinion) the value of cargo is still higher than the value of a man, or the value of environmental benefits.”
He continues: “Everyone buys into the concept of a safer and greener business, but only if it doesn’t cost anything.
“As long as the value of the cargo is higher than the value of the vessel’s crew or the environment, the wall wash inspection will prevail because commercial interests will always demand what they perceive to be the strictest pre-loading inspections.”
Mr Johnson sees vessels as being held responsible for excessive tank cleaning despite the fact that this can occur as a result of pressures from commercial interests, who mandate methods of inspection such as wall wash analysis. He suggests a surcharge or “green tax” that can go toward the costs of cleaning up the ocean. He says: “If commercial interests were partly or equally liable, maybe there would be more willingness to adopt safer and more environmentally aware processes.”