This is a transcript of the Belzona “Solve It Session” webinar – Long-Term Marine Maintenance Made Simple. Take a closer look at each section using the drop-down menu or watch the full webinar recording below:
One of the easiest ways to categorise the type of marine maintenance required is by its location. Either out at sea or in dry dock.
Of course, each of these areas have their own separate characteristics…
Characteristics of at sea maintenance
At sea repairs tend to be smaller in scale and due to their location, they are more than likely an emergency. Perhaps a leak that has sprung up out of nowhere and needs fixing immediately.
As a result, any at-sea maintenance needs to be done in situ – this way the ship or vessel can get back on its way as quickly as possible.
Characteristics of dry dock maintenance
Typically this involves larger applications – quite often beneath the waterline. For example, it could be related to propulsion and steering equipment, which is impossible to access anywhere other than in a dry dock scenario.
Therefore, with such severe or progressive issues, this allows Engineers to plan a maintenance schedule around such complex requirements.
Conditions whilst floating around on the water are conducive to two main issues – corrosion and erosion. Fixing problems that arise from these issues normally means a temporary repair until getting back to port. Especially considering the limitations associated with applications at sea, with ease of use being a fundamental concern for any prospective repair method.
Access to specialist equipment is limited or, more often than not, non-existent. So, all materials and methods have to be adaptable based upon the application conditions – this could be the adverse weather or the presence of oily and wet substrates. Either way, the tools need to match the requirements.
Belzona’s solutions for at sea maintenance, are crucially easy-to-use, fast-curing and surface-tolerant. Overall, helping to facilitate a fast return to service.
Shaft Rebuilt Using Forming Technique
Common applications include repairing and rebuilding mechanical equipment using forming techniques. Repairing worn shafts can be very tricky at sea, as it normally requires the disassembly of equipment and removal of the shaft for workshop repair, usually by welding and machining back to tolerance.
The shaft in this instance was worn and placed increased pressure on the bearing – shortening the service life.
Belzona’s paste-grade materials are 100% solids, and do not change shape during curing. Therefore they can be used to rebuild components to fine tolerances by using pre-made formers. This allows for quick and easy application and can be done in situ, without the need for disassembling equipment.
In this instance, Belzona 1111 was chosen in line with the forming technique, providing precise restoration of the shaft diameter.
Rapid Repair Allows Oil Tanker to Sail
Oil tanker, Italy (2017)
Leaking pipework presents unique challenges in an at sea environment. Due to restricted space and limited availability of equipment, it is often not possible to carry out thorough surface preparation. Coupled with the often wet and oily conditions, carrying out repairs can be quite difficult.
In this case, the leaking pipeline was part of the cooling system, hence the ship was unable to operate at full capacity until the leak was fixed. On closer inspection, there were multiple areas of low metal thickness.
By utilising Belzona’s fast-curing repair materials, the leak was arrested in less than 1 hour, as a temporary measure. The repair was then overwrapped with Belzona’s surface tolerant materials – creating a strong and long lasting repair with minimal surface preparation, directly onto a water contaminated surface.
The presence of oily, moisture-contaminated and submerged substrates are common-place at sea. Which makes achieving the desired level of surface preparation particularly difficult. Therefore, having access to surface-tolerant materials can make at-sea repairs, such as leak sealing, that much simpler!
One of the most versatile materials available is Belzona 1212 – watch the video below to see what makes it an essential part of any marine maintenance kit.
Moving off the ocean let’s enter the dry dock phase of marine maintenance!
During these planned maintenance periods, all manner of repair and protection can be carried out – from small applications, such as bonding fenders, to large scale projects on propulsion and steering equipment.
Yet, the high costs associated with being in dry dock mean that there are strict schedules to adhere to, made even more important when also trying to gain approval from classification surveyors. Belzona’s solutions can be applied quickly and easily, regardless of the size, helping to meet these requirements in a timely manner.
Elastomer Repair on Kamewa Impeller Duct
Ferry Operator, Italy (2006)
The impeller duct lining had been significantly deteriorated due to erosion at high flow rates.
To dismantle the assembly, replace the urethane lining and reassemble would have been both costly and time consuming. Repairing the urethane lining with Belzona 2311 avoided the need for dismantling of the equipment, and delivered the repair at a fraction of the cost of the alternative. Meanwhile ensuring long-lasting erosion and cavitation protection.
Considering all factors, including downtime and labour, it was estimated that there were savings of more than €150,000.
Ferry Bow Thrusters Protected From Cavitation
Scandinavian Ferry Company (2002)
The glass flake lining on this propulsion unit was irreparably damaged. During inspection, severe cavitation had been identified in specific areas of the bow thruster tunnels.
The existing coating was removed and then Belzona 1111 was used to restore the metal loss. A specialised cavitation resistance coating was selected, in the shape of Belzona 2141, to provide long-term protection. By doing this it was possible to offer the optimum protective solution at the best possible cost.
After 9 years, this was still in excellent condition and relieved the vessel from its annual docking cycle, extending it to every two years.
Bonding and Shimming
Injection Plate Bonding On Ship's Deck
Shipyard, South Africa (2017)
The stern of the ship’s main deck was badly damaged by years of corrosion and wear and tear. So, a test was done to measure the metal loss. The corrosion was so severe that they initially made plans to cut out and replace the entire deck. But in the end this was deemed impractical and expensive due to the danger of damaging equipment and objects installed below the deck.
Instead, new deck plating could be bonded with Belzona 1111 and the cavity filled by injecting Belzona 1321 in between. This provided 100% contact across the whole area. As you can see in the pictures, this was then over-coated with Belzona 5811, an immersion resistant coating to provide long-term protection.
Not only did it satisfy the ship owner, but it was an approved repair by Bureau Veritas. Plus, this method saved the owners at least 20% of the costs associated with cutting out the old deck and was installed in less than 48 hours.
Reseating New Rudder Bearing Via Injection Bonding
Vessel, Bulgaria (2010)
Another class-society-approved application is to re-seat bearings by rebuilding the corroded housing. Corrosion, coupled with severe wear, had increased the annular space between the bearing and the housing. Meanwhile, the housing itself had been damaged too. Normally this repair would require the building up of material, followed by precise machining – which is both time consuming and difficult. Therefore, a new bronze bearing needed to be installed into the oversized housing.
After using jacking bolts to set the bearing into position, Belzona 1221 was used to seal around the base. This was followed by injecting Belzona 1321 until the product exuded – creating 100% contact. Belzona saved time and money against expensive machining of the housing and supply of larger bronze bush. No alternative was fast enough to compete. This standard repair procedure eliminates galvanic corrosion and provides long term location of the bearing.
Versatility is the key characteristic of this marine maintenance essential. Typically used as a coating for the protection of equipment operating under immersion in aqueous solutions, Belzona 5811 eliminates corrosion, as well as providing outstanding chemical resistance. This makes it an ideal solution for coating areas that are frequently awash with sea water – such as decks.
However, it can also serve the purpose of being injected! The fluid properties of this system mean it can be used to fill voids, providing 100% contact between two substrates – acting as a high-strength structural adhesive for metal bonding. See this injection method in action below.