What is a rising stem gate valve?
Rising stem valves provide a stem that rises or falls as the valve opens or closes. This means that the actuation system converts rotational motion into linear movement of the valve stem when it is in operation. So, unlike its non-rising counterpart, the valve stem in this design indicates the position of the valve disc. In this article, we will review a rising stem gate valve, a rising stem ball valve, and a rising stem globe valve, and compare the rising stem valve vs. its non-rising counterpart.
Uses of rising stem gate valve
Generally, gate valves serve to start or stop flow, rather than regulate it. As a result, the valve disc is completely removed from the flow path when in the open position, which minimizes pressure drop. But when in a completely closed position, there is no flow and no pressure drop.
This feature makes it the go-to option in isolation applications, especially in large-diameter and high-pressure lines. The rising stem gate valve has its thread external to the valve body. So, when the handwheel is rotated, it drives the nut within the bonnet, leading to the raising or lowering of the stem.
Thus, identifying the position of the valve is made easy as the rising stem is always up when open and down when closed. As such, a larger installation height is required for this valve design relative to the non-rising design. Another advantage of this design is the ease of lubrication because the threading is exposed.
Certainly! Here’s more information about rising stem gate valves:
Rising stem gate valves are a type of valve that is widely used for on/off isolation applications, particularly in large-diameter and high-pressure pipelines. They are designed to start or stop the flow of fluid by lifting or lowering a gate or wedge-shaped disc that moves perpendicular to the flow path.
Here are some key features and characteristics of rising stem gate valves:
Construction: Rising stem gate valves consist of a valve body, a gate or disc, a stem, and a bonnet. The gate or disc is connected to the stem, which rises or falls as the valve is operated.
Linear Motion:
The stem of a rising stem gate valve moves in a linear, vertical direction as the valve is opened or closed. This linear motion provides a visual indication of the valve position, as the stem is fully extended (upward position) when the valve is open and fully retracted (downward position) when the valve is closed.
External Stem Thread:
The stem of a rising stem gate valve has its threading external to the valve body. This means that when the handwheel or actuator is rotated, it engages with a nut located within the bonnet, causing the stem to rise or lower.
Pressure Drop:
When a rising stem gate valve is fully open, the gate or disc is completely removed from the flow path, resulting in minimal pressure drop across the valve. This feature makes rising stem gate valves suitable for applications where pressure loss needs to be minimized.
Installation Height:
One consideration with rising stem gate valves is the required installation height. Due to the design of the external stem thread, a larger installation height is typically needed compared to non-rising stem gate valves. This should be taken into account when planning the installation and ensuring sufficient space.
Lubrication:
Rising stem gate valves often have the advantage of easy lubrication. The exposed stem threading allows for the convenient application of lubricants, ensuring smooth operation and reducing wear and friction between the stem and other valve components.
Rising stem gate valves are commonly used in industries such as oil and gas, petrochemicals, power generation, water treatment, and more. They are suitable for applications that require reliable shut-offs, such as pipeline isolation, tank and vessel draining, and process flow control.
It’s important to note that specific designs and variations of rising stem gate valves may exist, and the exact features and specifications can vary between manufacturers and applications. Consulting the valve manufacturer’s documentation or industry standards is recommended for detailed information on a particular rising stem gate valve.
