High Pressure Ball Valve Subsea

Similar with High and Medium Pressure valve  many use in subsea application.
Subsea valves are used to isolate or control the flow of fluid through underwater pipeline or other apparatus. Most commonly used in offshore oil and gas projects.
Design of valve is have function in a sub-marine environment, withstanding the effects of raised external pressure, salt-water corrosion, and other underwater effects. Certain application such as Remotely Operated underwater Vehicle (ROV) or bathyscaphe. Others application High Pressure Ball Valve in   Oil and Gas Industry :

• Well-Head Control Panels
• Chemical Injection Skids
• Hydraulic Power Units
• Subsea Work-Over Panels
• Alternative fuel

Paddle Assembly Subsea

Operating valves in a subsea environment use several of electric, hydraulic, or manual actuation. The type of actuation is always dependent on the system and the application. Manual and ROV is manipulated valves with provides an API 17H compliant valve handle that meets the operating standards of ROV, manipulators and ROV interface tooling, called paddle assemblies. This style of handle is use subsea ball valves, needle valves, and subsea systems, that allow an ROV to function the valve. The material used is a high-grade stainless steel that has excellent corrosion resistance and strength for the harsh subsea environment. Equipped with a limit design, the paddle assembly prevents ROV over-torque from affecting the normal use of the valve. With a modular approach, the paddle design will work with nearly every brand and configuration of subsea instrument valves on the market.

Difference between Subsea Valves and General Valves

• Need to consider the material of valve and compatibility of seawater, design external pressure seal structure, solve the influence from seawater pressure to moving parts of valves.
• More difficult to operate and control in seawater.
  Causticity of Seawater
  ● Salinity of seawater is 3%～3.5% :A kind of nature electrolytic quality with strong causticity
  ● Chloride damage metal passivation film and hinder the form of metal passivation film.
• Commonly used materials in seabed : SS 316, Duplex 2205 , Duplex 2507, Inconel 625 with Corrosion resistance gradually increased
• End connection is design with high pressure Fitting.

Since seawater has force acting on the components exposed to seawater, effect switch operation of valves.

For example, in FITOK subsea hydraulic needle valves, force direction from seawater to piston stem is upward, to upper stem is downward. Since the both stems have equal diameter (d1 = d2), so the total force from seawater to piston stem and upper valve stem is zero. In this way ,seawater can not effect switch operation of valves.