In the intricate realm of ship machinery crucial for seamless operations, each part is essential. Particularly, a globe valve plays a vital role by regulating fluid flow within a ship’s intricate systems, ensuring smooth sailing and operational efficiency on the high seas.
What Is A Globe Valve?
A globe valve, a type of valve frequently employed on ships, particularly in bilge suction lines, operates as a linear motion valve for fluid regulation. Its spherical shape encases the valve seat and disc within its structure.
The typical configuration of a globe valve includes the valve seat and disc positioned perpendicular to the valve’s axis. Movement of the disc away from the seat, in a perpendicular motion, creates a gap for fluid flow, thus opening the valve. Widely used in marine settings, globe valves are linear motion devices designed to control flow by starting, stopping, and regulating fluid passage. Specialized globe valves can also serve for isolation and throttling purposes. Notably, these valves incur higher pressure drops compared to direct-flow valves like ball and gate valves.
Marine Globe Valve Diagram
Body: The main structure of the globe valve that houses all the internal components.
Spindle Wheel and Nut: The spindle wheel, typically connected to a handwheel or actuator, is used to rotate the spindle. The nut is part of the screw mechanism that converts the rotational motion of the wheel into linear motion of the spindle.
Yoke Nut: Supports the valve stem and helps in the opening and closing of the valve.
Gland Packing: Located around the valve stem, this packing prevents leaks around the stem.
Gland Bolt: Secures the gland packing in place.
Stem: Connects the actuating mechanism to the valve plug (disc) to control the flow of fluid.
Bonnet: Covers the valve internals and provides access for maintenance.
Disc: Also known as the valve plug, this part controls the flow by moving against or with the disc seat.
Disc Seat: The seating surface against which the disc closes to stop the flow of fluid.
Inlet and Outlet: Where the fluid enters and exits the valve respectively.
How Does A Globe Valve Work?
A globe valve operates by controlling the flow of fluid through a pipeline. Here’s a simplified explanation of how a globe valve works:
Valve Body: A globe valve consists of a spherical-shaped body with an internal baffle that directs the flow of fluid through the valve.
Valve Seat and Disc: Inside the valve body, there is a stationary ring called the valve seat and a movable element called the disc or plug.
Flow Regulation: When the valve is in the closed position, the disc is pressed against the valve seat, blocking the flow of fluid. When the valve is opened, the disc is lifted away from the seat, creating a passage for the fluid to flow through.
Control Mechanism: The movement of the disc is controlled by a stem connected to a handle or actuator outside the valve. Turning the handle or activating the actuator moves the disc up or down to adjust the flow rate through the valve.
Regulating Flow: By adjusting the position of the disc, the operator can regulate the flow of fluid passing through the valve. This precise control allows for throttling, starting, and stopping the flow as needed.
Pressure Drop: Globe valves typically create a higher pressure drop compared to other types of valves like ball valves or gate valves due to the fluid flow path and the design of the valve seat and disc arrangement.
Globe Valve Types
Z-Body Type Valve
This design is the simplest and most commonly used for applications involving water flow. The Z-shaped diaphragm in the bulbous body gives it its name. The stem and disc move perpendicularly to the valve body, aligning with the horizontally arranged seat. The stem passes through the bonnet attached to a wide opening at the top.
Y Pattern Globe Valve
The Y pattern globe valve design addresses pressure drop issues common in globe valves. In this design, the valve seat and stem are angled at approximately 45° to the valve axis, providing a straighter path for fluid flow, creating a more pressure-resistant environment within the valve. While suitable for high-pressure applications, smaller Y pattern globe valves may not effectively resist pressure during throttling due to less streamlined flow passages.
Y-Patter Globe Valve Flow Direction
In a Y Pattern Globe Valve, the flow direction is guided by the angled valve seat and stem arrangement, which directs the fluid in a straighter path through the valve, enhancing flow efficiency and pressure resistance within the system.
Angle Globe Valve
The angle globe valve is a modification of the Z-shaped globe valve design. In this design, the inlet and outlet ends are placed at right angles, and the diaphragm is typically a simple flat plate. The fluid flows through the valve body in a right-angled path, discharging downwards in a more symmetrical manner. Ideal for high-pressure applications, the valve functions similarly to the Z-Body Type Valve in moderate conditions.
Marine Globe Valve Applications
In marine applications, different types of globe valves cater to specific functions:
Z-body Type Globe Valve For Ship Ballast System
In maritime environments, the Z-Body Type Globe Valve plays a crucial role in water flow control, particularly in ballast systems. With a basic yet effective design, this valve type facilitates essential functions onboard vessels.
Primarily utilized for adjusting buoyancy by filling or emptying ballast tanks, the Z-Body Globe Valve ensures precise control over the ship’s weight distribution. Moreover, it regulates the flow of cooling water to engines, contributing to the efficient operation of marine propulsion systems. Additionally, this valve type is instrumental in managing water drainage from the hull, helping maintain optimal conditions within the vessel.
Y Pattern Globe Valve For High-Pressure Steam Systems
In high-pressure steam systems, the Y Pattern Globe Valve is a specialized component designed to address pressure drop challenges commonly encountered in valve systems. This valve type is meticulously engineered to optimize performance in demanding steam applications, ensuring minimal pressure loss throughout the system.
Beyond steam environments, the Y Pattern Globe Valve finds its utility in hydraulic systems, where it excels in regulating fluid flow and maintaining precise pressure levels. Additionally, in fuel systems aboard various vessels, this valve type plays a critical role in controlling the flow of fuel to engines, ensuring efficient and reliable operation.
Marine Angle Globe Valve For High-Pressure Fuel Lines
Within marine contexts, the angle globe valve tailored for high-pressure fuel lines represents a modified iteration of the Z-Body design. This specialized valve variant serves as a key component in optimizing fluid control within critical maritime systems.
Specifically engineered for high-pressure fuel lines, the Angle Valve ensures the seamless and efficient flow of fuel, contributing to the reliable operation of marine propulsion systems. Moreover, this globe valve type is adept at regulating the flow of water or extinguishing agents in fire suppression systems, enhancing safety measures onboard vessels. Furthermore, in steam systems utilized across various shipboard applications, the Angle Valve plays a pivotal role in controlling steam flow, maintaining operational efficiency throughout the vessel.
