Process approval for revolutionary FPSO hull reinforcement solution

 

FPSOs are subject to some of the world’s harshest environmental conditions, and while owners have high expectation for the lifespan of their offshore units, decades of production take their toll. One of the primary areas where FPSOs sustain damage is the hull, which requires extra levels of protection and maintenance.

For the last six years, Bureau Veritas has been working with Cold Pad, a group of structural engineers, naval architects and researchers providing permanent repair and fastening solutions for ship hulls and decks using non-intrusive techniques. This month, Bureau Veritas awarded full class approval to Cold Pad’s revolutionary ColdShield^TM product: a unique, bonding-based reinforcement solution for FPSO hull girder strength.

Moving from hot works to cold works

"Traditionally, FPSO hulls are repaired using hot works processes like crop and renew, where damaged or corroded plates are cut off and replaced using heat-based techniques, such as grinding and welding, " says Xabier Errotabehere, Chief Technical Officer at Cold Pad.

"Beyond being time-consuming and costly – due to operational disruptions, the need to clean and vent the tanks and build scaffolding – this method can temporarily weaken the hull’s structure and put personnel at risk, given the proximity of hot works to the highly flammable oil stored on FPSOs."

ColdShield^TM is a major step forward for the industry, significantly improving safety for personnel performing repairs by eliminating the need for hot works. Instead, a reinforcing plate is installed over the damaged hull through adhesive bonding, strengthening the FPSO’s local steel plating and stiffening corroded areas. This technique has the added advantages of limiting operational interruptions and being both faster and consequently cheaper than traditional welding.

While bonding techniques are used in several industrial fields (e.g. aeronautics, automotive, civil engineering), they are often considered unreliable by the offshore industry. The major concerns with bonding have been the exposure of materials to harsh environments, a lack of field installation parameters and the unpredictability of mechanical performance.

“Our solution addresses these concerns by encapsulating the polymer bonding materials in an envelope made of highly durable fluorosilicone material,” explains Xabier. “This allows us to overcome the technical limitations associated with bonded solutions. We can protect materials from damage and corrosion, offer a controlled installation process and mastery of the reinforcement system’s mechanical behaviors.” Because of this, ColdShield is now an approved repair solution, fully certified for non-immersed areas, with a minimum design life of 10 years.

The path to approving ColdShield

To secure Bureau Veritas’ third-party approval – a process comprising Basic Approval Certification, Type Approval Certification and Process Approval Certification – Cold Pad had to prove ColdShield’s resilience in the harshest conditions.

Bureau Veritas approved the Coldshield^TM concept, overseeing the material selection and installation processes, while testing the resistance, durability and fatigue aspects of the technology. Cold Pad experts had to demonstrate that the reinforcement plate could withstand severe static and dynamic mechanical and thermal loadings, as well as resist ageing processes. ColdShield^TM manufacturing plants were audited, and experts confirmed that the delivered product met all required specifications. To deliver the final Process Approval Certificate, Bureau Veritas experts witnessed the installation of ColdShield^TM and confirmed the solution as fit for purpose.

Bureau Veritas is pleased to have supported Cold Pad in offering the oil and gas market a reliable hull reinforcement solution for FPSO hulls. Through its involvement at the earliest stages of the project, Bureau Veritas’ team of engineers, composite materials experts and naval architects were able to help enhance the solution’s design and development process. This made Bureau Veritas the natural partner for Cold Pad during the manufacturing process audit, installation review, and third-party class approval, and we hope to continue supporting Cold Pad for a long time to come.

Photo Credit: ColdPad