A Floating Production Storage and Offloading (FPSO) unit is a floating vessel used by the offshore oil and gas industry for the production and processing of hydrocarbons, and for the storage of oil. When oil and gas are processed, they are safely stored in the FPSO until they can be offloaded onto a shuttle tanker.
The tanks in FPSO are normally constructed to store processed crude oil and sea water ballast for stability. Ballast tanks are continuously exposed to a corrosive environment. Typically, ballast condition is worst in terms of corrosion damage, particularly in empty or partially filled conditions. Crude oil itself is not corrosive, but it may contain impurities and components that can cause corrosion. This has subjected the shell plating and the bottom plating of the FPSO hull to thickness loss in the long run.
Majority of the shell plating and bottom plating externally are exposed under the sea water. Traditionally, vessel will be in drydock to carry out ship repairs. Disconnecting a FPSO is an expensive task. These operations require specialised marine equipment, skilled personnel, and potentially the involvement of offshore support vessels. Once the FPSO is disconnected, it needs to be towed or transported to the drydock facility.
The Complexities of Cofferdam Ship Repair Solution
To prevent the production loss, repairing underwater shell plating and bottom plating has been utilising cofferdam. A cofferdam typically involves isolating the damaged section of the hull to create a dry working area for the ship repair. The cofferdam is installed around the damaged section of the hull. This may require welding or bolting the cofferdam to the existing structure to ensure a secure fit by divers.
Hazards can arise from the underwater environment, the nature of the ship repair work, and the presence of personnel and equipment in a potentially challenging setting. Divers face risks such as decompression sickness, nitrogen narcosis, equipment failure, entanglement, and limited visibility. Strict adherence to safety protocols and proper training are essential to mitigate these hazards.
Sandwich Plate System as a Ship Repair Solution
Sandwich Plate System (SPS) is a structural composite material that consists of two metal plates bonded with a solid elastomer core. SPS was developed by SPS Technology, the world’s leading supplier of structural reinforcement solutions to the offshore and maritime industries.
SPS is a mature proven ship repair solution in the maritime market. The first recorded project involving SPS was carried out on the P&O Pride of Cherbourg, a Lloyd’s Register approved vessel in 1999. Therefore, SPS has been in the market for about 25 years. The first ship repair using SPS was carried out in 2003 for Conoco Phillips FPSO Independences bottom plating.
Advantages of SPS Ship Repair Solution for Bottom Plating and Side Shell Plating
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Safety
SPS cold work solutions eliminate the need for hot work in hazardous environments, such as those involving flammable cargo, materials, or gases. This reduces the risk of fire, explosion, or injury to personnel and the environment. SPS can prevent cofferdam and eliminate the requirements of divers. This is because all the ship repair works are carried out in the tanks instead of underwater. -
Time
SPS cold work solutions require less preparation, installation, and inspection time than conventional ship repair solutions. SPS can be installed in parallel with other activities, without disrupting the normal operation of the FPSO. SPS also eliminates the need of tank cleaning of adjacent tanks, which can be costly and time-consuming. Weather conditions and environmental factor for diving operations are negligible as all the ship repair work are carried out in the tank without involving overboard works. -
Cost
SPS cold work solutions require less labour and material than conventional ship repair solutions. SPS can save up to 90% of labour and 56% of steel compared to crop and renew techniques. SPS can also reduce the maintenance and operational costs of the FPSO by extending its service life and enhancing its performance. Commercial diving is risky and expensive. These are not required for SPS ship repair solution. The needs for DSV (Diver Support Vessel) are also eliminated with SPS. -
Quality
SPS cold work solutions provide a permanent, durable, and class-approved structural reinforcement solution repair that restores or improves the structural integrity of the FPSO. SPS can also provide superior protection against corrosion, fatigue, impact, and blast. Therefore, SPS ship repair solutions can provide a safe, fast, cost-effective, and high-quality alternative for repairing the shell plating and bottom plating of FPSO. SPS is approved by all major classification societies and has been used in over 500 projects worldwide.
SPS Repair for Bottom Plate: Credits SPS Technology
Quality Assurance with SPS Structural Reinforcement Solutions
Sandwich Plate System (SPS) ship repair solution for FPSO is promising, as the technology is evolving and gaining acceptance in the offshore industry. The technology is constantly improving to meet the challenges and demands of the offshore industry. New methods, and products are being developed to enhance the performance, durability, and reliability of composite structural reinforcement solutions.
The technology is subject to various standards and regulations from different authorities and organisations. These standards and regulations aim to ensure the safety, quality, and consistency of composite structural reinforcement solutions. All majority IACS Classifications Societies has published Rules/Guides for Composite Repairs. Some of the professional bodies like AMPP and API has started to recognise the potential benefits of the composite structural reinforcement solutions.