Optimizing water management with innovative cleaning techniques

Committed to lowering the risks associated with managing water in offshore environments, Offshore Water Management LTD (OWM) has continued to drive industry change throughout its 15 years of operation, proving itself to be a vital component of offshore operations across the globe.   

Utilizing first-hand industry experience, the specialist team of engineers, samplers and auditors supports offshore operators with the mitigation of water-related challenges, spearheading tangible change in the industry. With specialist knowledge of auditing, treating and managing potable water in the extreme conditions associated with offshore operations, the company’s services offer operators complete confidence that any onboard water supply is safe and fully compliant with all relevant regulations. 

It is well-documented that there are considerable risks associated with potable water in an offshore environment, such as contamination by saltwater, oil spills, or other pollutants. Contamination poses a significant risk to employee health, therefore, it's imperative that the water is thoroughly evaluated and treated, and all water storage is monitored and cleaned regularly to ensure it meets the necessary safety standards. 

Recognizing the critical nature of managing offshore potable water supply, OWM draws on nearly two decades of experience and knowledge to tackle the unique challenges faced in every water management project. This first-hand expertise allows its team to quickly identify the appropriate solution to provide safe drinking water to an offshore location, which can be a challenge, due to factors such as distance from the source, water quality, environmental conditions and extensive regulations. Despite these hurdles, OWM is committed to providing access to clean and safe drinking water, which is crucial to the health and wellbeing of offshore workers across the entire industry.   

As technology advances, there is an increasing amount of water-related innovation that makes providing a clean, safe water supply a much easier feat. As the global authority for offshore potable water management services, the company’s offerings include consultancy, compliance, products, training, advisory and support to the energy and marine sectors. This expertise uniquely positions work water management experts to conduct cleaning, disinfection, reactivation and sampling alongside the ability to complete any remedial works that arise during these processes. Supported by a global laboratory network, the company is driven by multi-sector capabilities to challenge industry processes and evolve water management best practices worldwide. 

Potable water. From remote locations and turbulent conditions to limited space and high numbers of personnel, managing access to drinking water for vessels and offshore platforms comes with many challenges. In light of this, there are many legal requirements that asset owners and operators are required to comply with. These legislations are designed to ensure that all potable water is regularly monitored to effectively manage the risks associated with hazardous bacteria that can cause severe illness.  

In addition to employee health considerations, water-related illnesses are a major cause of avoidable downtime that amounts to additional, negatable costs. Contamination is not unusual, but not all contaminants are pathogenic; in some cases, while the water is still considered potable, contamination can cause a strong taste or odor that makes it unsuitable for consumption.  

Water purity challenge. While not unique to the offshore environment, contamination also can come from within the water system itself. Due to the ageing-nature of assets in the North Sea, this is a problem that is being seen more regularly. As it is not always practical or possible to remove ageing, iron-containing pipework, solutions have been developed to prevent internal system corrosion—this includes the use of chemical treatment and point-of-use filtration systems that remove contamination before it reaches personnel, Fig. 1.  

Fig. 1. Hypochlorite injection system.

There are several options for managing an offshore drinking water supply, which range from containerized solutions to the provision of water bottles. While supplying bottled water may seem like a simple solution to a complex problem, there are additional factors, such as storage and the environmental impact of the production, transport and disposal of plastic bottles. Considering these factors, many operators prefer to utilize containerized water storage technology to maintain a high standard of potable water. These technologies can include water desalination through reverse osmosis, filtration cartridges and water conditioning with chemical additives. 

Regardless of the solution selected, effective management and regular cleaning and disinfection are an essential part of any water management system. Providing fully accredited water management solutions, OWM’s advice, solutions and consultancy services are based on extensive project and engineering experience, in addition to a comprehensive, technical understanding of the products available.    

In addition to technical understanding, extensive knowledge surrounding the laws and regulations safeguarding offshore water is crucial when operating in an offshore environment. For example, a storage tank located offshore from the UK must be audited under the International Safety Management (ISM) code; microbiological and chemical analysis must be performed every quarter, with the participating laboratories required to be UKAS accredited. 

As fully certified and accredited risk assessors, OWM provides a potable water risk assessment service, allowing for complete compliance with legal and marine regulations; drawing on two decades of first-hand experience, the unique risk assessment format has been designed specifically with the challenges of offshore and marine environments in mind. The company’s processes are at the forefront of technology, downtime is kept to an absolute minimum, and all statutory requirements are met, giving complete compliance confidence. 

The guidance in the UK is set by the Drinking Water Inspectorate and Marine Safety Forum (MSF), and it follows the Approved Code of Practice L8 for the control of legionella bacteria in water systems. The MSF set guidelines for the super chlorination process in Appendix 2 of Delivering Quality Potable Water to Offshore Installations. UK and Scottish Legislation is based on the Drinking Water Directive 1998 set in Europe—following guidelines from the World Health Organization on drinking-water quality, Fig. 2. 

Fig. 2. A schematic of the hypochlorite injection technology.

Case study: Rapid response tank cleaning. When it comes to potable water, safety needs to be the highest priority. Therefore, thorough cleaning and disinfection are a necessity for all offshore water-related operations. It is critical to ensure that water storage tanks are consistently monitored and managed to provide clean and safe-to-consume drinking water. Over time, tanks can become contaminated with biofilm ‘slime’ caused by settled deposits—without appropriate measures, this biofilm can ultimately facilitate the proliferation of pathogenic bacteria, which threatens the health of those consuming the water.  

With water tanks in operation across drilling rigs, platforms and FPSOs, the importance of tank maintenance cannot be underestimated or ignored. In a recent rapid response project, the company provided inspection, disinfection and cleaning for four water storage tanks in Newcastle, UK. Each of the four tanks measured more than 10 m in height, and as such, when approaching another provider, the client had been quoted a three-week timescale that included scaffolding construction and a requirement for eight personnel. Utilizing innovative cleaning technology, OWM committed to a four-day turnaround with no scaffolding requirements, reduced personnel and drastically minimized waste and risk.  

Tank cleaning solution. The company’s first venture into tank cleaning began more than a decade ago. While performing tank inspections after having been cleaned by other contractors, OWM identified gaps in the methods applied and details that had been overlooked. Committed to redefining the industry standard for tank cleaning, the water management experts embarked on a trial-and-error process to adapt its cleaning system, incorporating unique methods to reduce the manpower, equipment, and chemical usage.  

In the initial stages of the chemical cleaning discovery process, batches had to be made up in a drum before pumping into the tanks for use—this required excessive manpower as the batches needed to be continuously monitored at all times during the clean. To negate this, OWM created a portable trolley which was designed to automate the process of proportionally mixing chemicals to the correct strength; following the mixing process, a built-in pump is able to transfer the chemical mix into the tank being cleaned through hoses.  

Typically, a tank cleaning job of this scale would begin with draining and opening each tank to allow for adequate ventilation before gas testing; the personnel would then enter the tanks to construct the required scaffolding. Following completion of this preparation stage, high-pressure washers and brush lances would be used to physically clean the surfaces—this is an incredibly labor-intensive process and depending on the tank's size and volume, it could take days to complete this stage alone.  

On completion of the cleaning, each tank would be completely drained of wastewater and the tank hatches would be refitted to allow sodium hypochlorite to be added, before filling the tanks again and completing the 50 ppm super-chlorination. Once full, each tank is required to be left for a minimum of two hours before neutralizing the solution, and once again draining the entire contents. Once empty, each tank would be filled and flushed again before finally being filled for use and sampled. 

Having identified the potential for the Panton McLeod PM100 onshore cleaning method to be employed in an offshore environment, OWM collaborated with Panton McLeod to develop an innovative hybrid cleaning process that brought all the benefits associated with the PM100 chemical to offshore environments.  By using this method in a recent rapid response job, OWM was able to avoid the extensive and time-consuming traditional methods that involve unnecessary risk and cost. The PM100 method reduces the number of stages required to complete the cleaning and disinfection by 33%.  

Looking at the rapid response project as an example, OWM’s team began the process by draining, opening and ventilating each tank before completing gas testing. This method removes the need for scaffolding, so the team was able to immediately begin rinsing down the tank surfaces with fresh water and follow up by applying the PM100 chemical, using the non-atomizing long-reach spray method. The tanks were then left for a short period to allow the chemical to break down any contaminants, which were then subsequently rinsed off with fresh water. To mitigate the risk associated with any remaining chemicals, a neutralizing process was then conducted before discharging the water to drain. Finally, the tanks were filled with fresh water before sampling and certificated, Fig. 3.  

Fig. 3. Before and after (right) images from a recent potable water tank cleaning project.

By utilizing the innovative hybrid PM100 cleaning and disinfection method, OWM was able to reduce the number of times wastewater was drained from each tank from four to two. This system of tank cleaning is considerably more cost-effective, safe and sustainable, as there are limited personnel on-site, no requirement to work from height, a significant reduction in the number of chemicals being pumped into drainage systems, and considerably less wastewater being produced. Another benefit of this process is that by removing the need to continuously fill and drain the tanks, the job can be completed in a much tighter timeframe, allowing for rapid response or emergency aid without the monumental operational impact demonstrated by traditional methods. 

Technical study: Pot water system cleaning, disinfection and re-activation. There are several indicators for when a potable water system requires cleaning and disinfection, these include: 

• When routine on-board testing indicates contamination. 
• When an inspection indicates contamination. Typically, it is recommended that tanks are inspected annually; however, in some markets such as Norway, this is a mandatory requirement.  
• Following any remedial action to the inside of the storage system. 
• Following storage tank entry by personnel. 
• Following any work on potable water pipework. 
• After any system refurbishment. 

When these situations arise, it is important to act quickly to negate any personnel illness and subsequent downtime. Another system employed by OWM is an Abulox Offshore Blend (AOB) System disinfection, which includes the complete inspection, cleaning and disinfection of filters, pipework, pumps, hoses, calorifiers, and hydrophores. This five-step process is specifically designed to allow for effective disinfection rates on all bacteria while also preventing bacterial growth and corrosion.  The disinfection is carried out using AOB, which is specifically designed to be used in the offshore environment. In comparison to traditional disinfection chemicals, which are generally Class 8 or 9 dangerous goods, AOB is a non-dangerous goods disinfectant, making it a much more reliable and safe option.  

Step one. To begin the process, the entire potable water system is fully purged of all contents and thoroughly cleaned to remove all sludge, residual water and biofilms. In addition, dead-legs and any components of the system that have minimal or no flow, are drained locally.  

Step two. To be fully isolated, the tank is refilled with fresh water and then super-chlorinated to increase the chlorine concentration of the drinking water supply to above the guideline of 5mg/L to chlorinate the onboard systems, disinfecting the water and removing any bacteria. 

Step three. Following super-chlorination, the chemically treated water is drawn through the entire distribution system; this includes filters, pipework, pumps, hoses, calorifiers and hydrophores. 

Step four. To flush the distribution system, fresh water is pulled through all outlets to remove any remaining chemicals from the system before it is reactivated. 

Step five. Finally, sampling and testing are required to verify that the microbiology, legionella and chemical results are in line with all relevant legislation and regulations, offering complete assurance for OWM’s clients. 

Value delivered. In conclusion, providing safe, palatable water for offshore workers is critical and, though complicated, the heavy regulations ensure the safety of thousands of people every week. From specialist chemicals to reverse osmosis, OWM has delivered an extensive portfolio of successful projects, each one driven by offering innovative solutions for the bespoke requirements of every customer and their operations, propelling the risk prevention experts to become a global authority on offshore water management. 

Prioritizing safety above all else, the OWM team is committed to removing the risks associated with offshore drinking water across the world. Recognizing the importance of prioritizing the health and safety of offshore workers, the water management specialists operate internationally to support operators with their moral and legal obligations to provide a safe working environment for employees.