23/02/2017

Sweet Caroline


In October 2016, the HMS Caroline, a ship owned by the National Museum of the Royal Navy, was undergoing a hull refurbishment in dry dock at Harland and Wolff in Belfast, Ireland.  HMS Caroline is a decommissioned C-class light cruiser which saw combat service in World War I and served as an administrative centre in World War II. HMS Caroline was launched and commissioned in 1914. Due to the refurbishment, she is currently closed to the public, but is due to re-open in 2017.
 
It had been 30 years since HMS Caroline’s last overhaul, and numerous comportments, fuel tanks and storage areas below the waterline had been taking on water. This had resulted in scores of leaks when the ship entered dry dock, not to mention a very pitted surface. Originally designed for 20 years of service, she has now been operating for over 100 years. Welding was limited to areas of the hull that had no leaks, and that were robust enough to withstand hot works. The client was looking for a long-term repair solution, capable of bonding to a poor substrate and with rapid cure times as the project’s dry dock was already booked for another ship repair. Belzona materials were specified by Marine Surveyors, and the application was carried out by SPP Engineering Services. For this application, two Belzona materials were chosen as a means of providing an effective, long-lasting repair, Belzona 1111 (Super Metal) and Belzona 1212.

Prior to the application, the substrate was grit blasted, then cleaned.  Forced heating of the working area was used to keep the substrate and material above a temperature of 10⁰C. Due to the size of the project and the short working window, a team of Mixers, Runners and Applicators were utilised. Belzona 1111 was firstly used to fill in badly corroded areas. The material was also originally specified for sealing leaking rivets (coming from internal fuel storage tanks) but the poor substrate condition required a surface tolerant solution. As Belzona 1212 can be applied onto oily surfaces and even underwater, the material was chosen as the best alternative to Belzona 1111. This material is effective at displacing contaminants from the substrate via a strong electronic affinity with the metallic substrate, allowing the epoxy to penetrate the profile and create a strong mechanical bond. In the end, only 6kg of Belzona 1111 was used at deck level, and over 100kg of Belzona 1212 was utilised to seal the leaks due to the substrate conditions. The ship floated back to moorings before Christmas, with no leaks or delamination.
  
One of the Applicators on site said: “We would only approach such a highly complex and unusual project with full technical and site support from a trusted supplier like Belzona. The systems selected for this project had to be of the highest possible technical performance, as this ship will be a high profile floating museum open to the public”.

This project illustrates the versatility and use of Belzona products while providing a long-term solution to both problems. The high bond strength and no shrinkage characteristics of the materials made them the ideal choice for this repair. Belzona was the only fast and effective solution to the problem as welding was limited. The application was completed without using hot work thanks to Belzona 1111 and Belzona 1212's cold curing characteristics. Once complete, HMS Caroline will be returned to her home of Alexandra Dock in the Titanic Quarter in Belfast.