Maintaining Floating Asset Integrity

The straight answer of course, is that FPUs cannot physically or cost-effectively go to drydock for inspection, repair, and maintenance (IRM); particularly for the complex end of the IRM scale; on-station alternatives must be found. The quest for these solutions requires disruptive innovation, collaboration, agreement, and endorsement from owners, operators, regulators, including, particularly, the Classification societies (Class).

Collaboration through forums such as the Hull Inspection Techniques and Strategy Joint Industry Project (HITS JIP) passing its tenth anniversary this year, have developed diverless IRM techniques for FPUs. To demonstrate this success, this article will use sea valves on floating production, storage and offloading (FPSO) assets as an example of collaboration, research and development (R&D), and highly skilled technicians to apply the techniques.

Sea valves: do they matter?

The FPSO comprises three main parts: the topsides, the hull, and marine systems, and each part plays an important role in how the vessel operates and handles its tasks. The passage of water through the hull is essential to the installation’s operations: sea water inward; and produced water outward. Regular inspections and maintenance are necessary but can be expensive and time- consuming, as offshore repairs are difficult to carry out.

FPSO hull penetration sea valves are critical for controlling the flow of sea water in and out of the vessel, which is essential for processes such as cooling, equipment operation, and sea water injection.

• Cooling: FPSOs require significant amounts of sea water for cooling equipment and various processes; sea valves control the flow of sea water for cooling systems, ensuring efficient operation of the vessel’s machinery.
• Sea water injection: sometimes used to inject into oil wells to enhance production; sea valves are part of the system that manages sea water for this purpose, allowing for controlled injection into the wells.
• Overboard dumping: discharge of sea water overboard may be required for various reasons, such as cleaning or ballast water management; sea valves are part of the system for controlling the discharge of sea water.
• Process control: sea valves are also used to isolate and control various sea water-related systems, ensuring the safe and efficient operation of the FPSO.
• Sea water treatment: sea water may need to be treated to remove impurities like sulfates and air; sea valves are part of the system that manages the treatment and distribution of treated sea water.

Most sea water is drawn into the installation through sea chests. Therefore, sea valves are critical to the safe and effective operation of a floating production installation:

• Safety and reliability: critical for ensuring the safe and reliable operation of the FPSO, protecting equipment, and maintaining product quality.
• Efficiency: contributing to the overall efficiency of the FPSO by ensuring smooth and controlled operations.
• Environmental protection: proper valve function helps ensure that wastewater and other byproducts are treated and discharged into the sea in accordance with regulations.
• Downtime reduction: reliable sea valves minimise the risk of production interruptions, which can be costly.

As most intake of sea water and overboard discharges are below the water line, the sea valves control passage of water through penetrations in the wetted hull; their failure to open and close reliably and fully is a significant risk to hull integrity, operations, and Class or other regulatory compliance.

Sea valves are therefore integral to the entire FPSO and all FPU systems.

Read more from this article by signing up here for free, in the September/October issue of Oilfield Technology Magazine.

Read the article online at: https://www.oilfieldtechnology.com/offshore-and-subsea/05112025/maintaining-floating-asset-integrity/