Tank cleaning and tank inspection remain some of the most dangerous tasks on board tankers, but new approaches and technology are contributing to improved safety and efficiency
In many areas of tanker operation, dangerous practices on board have gradually been replaced or made significantly safer, but tank cleaning and inspection remain something of a anomaly. Still potentially lethal, these tasks have been made somewhat safer of late via unmanned machinery spaces and remote monitoring. There are also efforts being made to reduce the need for multiple tank washings and inspections through the use of spectrometers. Large charterers, such as Dow Chemicals, have also introduced remote inspections and robotics to mitigate the need for human entry.
Where human entry into tanks is still required, the safeguards needed are well known and should be understood. In this regard, The International Chamber of Shipping (ICS) has launched a new edition of the standard reference work for those working on tankers carrying chemical cargoes, the ICS Tanker Safety Guide (Chemicals). The fifth edition of the guide provides chemical tanker operators and crew with up-to-date best practice guidance for safe and pollution-free operations on ships regulated under Marpol Annex II. This includes oil tankers operating in accordance with Annex II when they are carrying chemical cargoes.
“Sadly, the industry continues to see the same type of incidents time and time again”
International Chamber of Shipping nautical director and project leader Chris Oliver said: “Senior industry experts have contributed their expertise and experience to the technical working group to help shape the new guide. We have worked to simplify this new edition and to make it easier to use – and hence more likely to be used. Techniques learned in the aviation industry have been incorporated to make the checklists more effective and the industry’s greater understanding of human factors means we can make the messaging more relevant to the user, and consequently more effective.”
He continued: “Sadly, the industry continues to see the same type of incidents time and time again. We have identified these areas and expanded the guidance on key safety issues, including enclosed space entry, risk assessments and PPE. This really is the essential guide for every tanker carrying chemical cargoes.”
He told Tanker Shipping & Trade that with regards to operational guides: “There is a better recognition in the industry that the human element – how people behave – has a big impact on operations.” When it comes to safety culture in a company, he feels that this should start at the top and work downwards so that the individual has a clear expectation of what is required.
This is especially important in the chemical tanker industry, where Mr Oliver feels that the inherent danger in some of the cargoes has led to greater awareness about safety, especially tank cleaning. “People who sail on tankers,” he said, “have long recognised the danger of enclosed space entry, because the commodities carried are dangerous.”
He added: “ICS has reinforced the requirement to follow closed space entry procedures: risk assessment, entry permits, and best practice and behaviours. We know there have been many accidents and fatalities due to unauthorised close space entry. This can happen for a number of reasons: non-compliance with procedures, poorly written procedures, poor supervision, complacency, equipment not being used properly or not working correctly. There is also the human element – understanding why an accident has happened in relation to the decisions made by those involved so that future accidents can be prevented.”
The latest enhancements to the tank cleaning process are coming from incremental gains in software efficiency. Manufacturers such as Scanjet PSM have worked with designers, operators, and engineers to resolve operational issues through digitalisation, while providing economical upgrade solutions.
Scanjet PSM technical sales director Mark Jones said integrated digital systems improve the safety and operational capabilities of vessels. “Access to new smart technology is vital in delivering efficiency and flexibility,” he said.
“Tank level measurement plays a vital role in maintaining safety and efficiency,” Mr Jones continued. Digital tank gauging systems are being adapted for emerging industry needs and higher safety requirements.
“As operating conditions continue to challenge vessel operators and owners, manufacturers and suppliers continue to support the digitalisation process through further development to ensure vital safety standards are met, while improving efficiency,” Mr Jones said.
Modern digital tank gauging systems are designed to be versatile, capable of handling process control across the full range of shipboard fluid types, from fuel oil and lubricants to ballast water. “Intelligent sensors collect real-time data from all onboard storage tanks, including anti-rolling tanks, and measure vessel draught and trim, as well as cargo tanks and water ingress detection,” said Mr Jones. “Sensors and transmitters, designed for temperature, pressure and level measurement, are typically networked via an onboard system.”
They use distributed termination modules to acquire the data and relay it to a centralised graphic display unit, which provides content indication and alarm status for all tanks.
“The ongoing challenges of the Covid-19 pandemic have also accelerated the need for change,” said Mr Jones. This is propelling owners and operators to invest in remote monitoring of onboard systems for safety and security, and in data analytics for trending, performance monitoring and benchmarking.
Tank cleaning also requires hot water and steam. One of the most established suppliers of steam generators for heating, cleaning and de-icing purposes is GESAB of Sweden. Its units range from 100 to 3,500 kg/hour and steam pressures from 3 to 10 bar.
For the final stages of tank washing, fresh water is often required. Norwegian reverse osmosis freshwater provider Norwater supplies low maintenance and low energy usage units to the tanker industry. The company now has more than 3,000 units in operation, including onboard the chemical carrier newbuilding Bow Orion.
Another well-established name in tank cleaning is Polarmarine, part of the Kockumation group of companies. Polar Jet tanker washing machines with Washmaster software from Kockumation are helping optimise this process. Proper monitoring results in better performance and routines can be adjusted without jeopardising the results.
Alfa Laval’s tank cleaning system, Toftejorg, also uses a software solution. The G-Pass design software produces a 3D simulation of the tank, optimising position, quantity, jet length and jet hit angle to prevent product build-up and reduce fluid and energy use.
On the methanol carrier sister ships Mari Couva and Mari Kokako, each zinc-coated tank is equipped with Polarmarine tank washing machines (two fixed per cargo tank, one per each slop tank, one in a residual tank) with inspection hatches if a surveyor needs to enter the cargo tanks. The operator, Waterfront Shipping, wanted to limit tank entry and consulted with L&I on the first-generation methanol carriers. The methanol carriers use tank washing analysis via a spectrometer as the primary cargo tank washing inspection system.
Butterworth, another name synonymous with tank cleaning, offers a stream impingent technology for faster cleaning while using less water, energy, and cleaning chemicals. Butterworth’s business line manager Darryl Kee told Tanker Shipping & Trade that Butterworth offers short-term and long-term leasing arrangements on its tank cleaning machines.