VALVE MAGAZINE Fall 2024

OFFSHORE PRODUCTION

Sea water is pumped from the ocean via a sea water lifting pump followed by further treatment including removal of sulfates and air before going through the cooling water valve. The challenge in this application is the high capacity and noise levels. Low pressure globe valves are required to handle high capacities and special trim is required to atten uate noise. As with every application aboard an FPSO, corrosion is a concern, therefore special materials for the body and trim must be used to mitigate damage. Commonly used body materials such as nickel aluminum bronze, duplex and Hastelloy C are highly effective and have excellent corrosion resistance. A combination of exotic alloys can be used for trim materials to help extend the life and functionality of the valve. Sea Water Injection Systems Sea water injection systems on an FPSO consist of overboard dump valves, pump recirculation and injection to well valves — each type critical to production. Each valve appli cation requires high rangeability and the ability to function with high-pressure fluctuations, cavitation and entrained particles. For example, the overboard dump valve is used for startup of the high-pressure injection pump. Even though it is only used at startup, it is critical to the process and must function on demand. The conditions are harsh containing high pressures that drop to atmospheric pressure at the outlet. Cavitation and vibration are associated with this process and operators should account for them. Cavitation is a phenomenon that occurs when the pres sure of a fluid drops below its vapor pressure and then recovers above the vapor pressure. As a result, bubbles form and then implode causing damage to the closest metal boundary, severely shortening a valve’s performance and life expectancy. Similarly, vibration from high pressure drops will also induce mechanical wear and fatigue on parts. A robust valve design must be selected with mul tistage trim to control the pressure drop in stages, elimi nating cavitation. One example is a valve used in high pres sure appli cations that

ASME-rated Lincoln Log valve. Source: Baker Hughes

corrosion resistant materials, and consistently maintain a class V shutoff. Cooling Water Valve With plentiful amounts of seawater available, the FPSO requires large quantities of water for applications to assist in operations, namely for cooling down equipment on the vessel and reinjection into the oil well for production.

Raw crude is separated then processed into final products and stored for transport. Source: Baker Hughes

Gas Treatment Dehydration and Compression

Gas to Gas Pipeline or Injection

uses multiple stages to elim inate cavita tion, taking the pressure drop in stages so the process fluid doesn’t drop below the vapor pressure at any point. In some cases, a downstream plate can

Oil, Gas and Water Separation

Oil to Oil Pipeline or Storage

Crude Oil Treatment

Wellhead Fluid

Water to Disposal or Injection

Water Treatment

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VALVE MAGAZINE

FALL 2024