NIBCO Gate Valves

What is a Gate Valve?

NIBCO gate valves are multi-purpose bi-directional shut-off valves for commercial and industrial applications. A gate valve either allows media to flow through the valve unobstructed or stops the flow of fluid.

The main advantage of a NIBCO gate valve is its straight-through, unobstructed passageway, which induces minimal pressure loss over the valve. However, gate valves are slower than quarter-turn valves and should only be used in the fully open or closed position.

NIBCO gate valves are primarily used with larger pipe diameters (from 2" to the largest pipelines) since they are less complex to construct than other types of valves in large sizes.

At high pressures, friction can become a problem for gate valves. As the gate is pushed against its guiding rail by the pressure of the medium, it becomes harder to operate the valve. Large gate valves are sometimes fitted with a bypass controlled by a smaller valve to reduce the pressure before using the gate valve itself.

How Does a Gate Valve Work?

A gate valve has seven main parts:

Handwheel
Stem
Gasket
Bonnet
Valve body
Flange
Gate

Gate valves are actuated by a threaded stem that connects the actuator (such as a handwheel) to the gate. They have either a rising or a non-rising stem, depending on which end of the stem is threaded. Most gate valves have a flanged or threaded connection.

Gate Valve Components

Stems

The gate on a gate valve is raised and lowered by spinning a threaded stem. A manual wheel or actuator then spins the stem. Depending on the design, it is either considered a rising stem gate valve or a non-rising stem gate valve. As the stem spins, it either raises or stays in place.

Rising Stems (OS&Y)

Outside Screw and Yoke (OS&Y), also referred to as rising stems, are fixed to the gate. The threads are on the actuation side of the valve. As the gate is raised or lowered, the stem moves up and down. This acts as a built-in visual indicator of the state of the valve and is easily lubricated. Since they have moving components, they cannot be used with bevel gears or actuators. Therefore, rising gate valves are suitable for manual actuation.

Rising Stem Gate Valve Diagram

Non-Rising Stems

A non-rising stem is fixed to the actuator and threaded into the gate. In addition, an indicator is often threaded onto the stem to show the open or closed state of the valve. Non-rising gate valves are standard in underground installations and applications with limited vertical space.

Non-Rising Stem Gate Valve Diagram

Bonnets

Bonnets provide leak-proof closure for the valve body. NIBCO gate valves may have a screw-in, union, or bolted bonnet.

Screw-In Bonnets

Screw-in bonnets are the simplest, offering a durable, pressure-tight seal.

Union Bonnets

Union bonnet is suitable for applications requiring frequent inspection and cleaning. They’re held in place by a union nut. The union nut sits on the lower edge of the bonnet and screws into the valve body threads. This type of design ensures that the leak-proof seal created by the nut does not deteriorate by frequent removal of the bonnet. It also gives the body added strength.