When metallic valves are exposed to certain chemicals and substances, they can rust, erode, and ultimately fail. In selecting valves for chemical industries, a crucial consideration is their ability to withstand the extreme properties of the pumped media. While the function of a valve is critical, its capacity to endure exposure to specific chemicals is equally important. Therefore, when choosing valves for chemical use, both functionality and durability should be taken into account. A long service life implies that the valve material will resist the extreme conditions of flow and fluid properties.
It’s important to note that there are numerous types of valves, and most of them are not industry-specific. However, certain valves perform exceptionally well when handling chemicals, including ball valves, gate valves, globe valves, plug valves, check valves, and various iterations.
Selecting the correct valve is instrumental in preventing unnecessary downtime and workplace hazards. Additionally, it helps to avoid environmental damage, fines, and penalties associated with such damages. The following paragraphs elaborate on valves that excel in chemical applications.
Ball Valve
The ball valve is employed to regulate flow and pressure, and one of its main features is its leak-proof design. This valve is particularly critical in chemical applications, especially where liquids are being transported. Its structure comprises a rotating ball with a hole, shifting 90 degrees to permit or block flow. Operated by an actuator or handwheel via a component known as the stem, these valves are widely used not only for their excellent function but also due to their cost-efficiency, quick operation, easy maintenance, and versatility in size to accommodate various flow rates and pressures.
Check Valve
A check valve is a two-port valve with openings for the inlet and outlet. Fluid flows through the equipment in only one direction, designed to prevent reverse flow. This valve lacks a valve stem and handle and is classified as an automatic valve. The automation is mechanical, with fluid pressure acting on the valve gate to force it open when the pumping system is activated. The advantages of this valve include its simple design, compact size, automatic operation, cost-effectiveness compared to gate valves, prevention of reverse flow, and minimal pressure drop.
Gate Valve
The gate valve is designed for shut-off, efficiently preventing any fluid flow. It is not recommended for throttling, as regulating flow with this device poses a high potential for disc damage over time. In terms of working principle, the valve has a plate that serves as a flow barrier, entering and retreating from the valve seats to block or permit fluid flow. Operated by a handwheel or actuator connected through a threaded stem, gate valves perform well in chemical plants handling liquids and slurry media, and to some extent, solids and gases. Advantages include versatility in size, easy installation, cleaning, and repair, and perfect shut-off.
Plug Valve
Plug valves, similar in design to ball valves, are classified as quarter-turn valves. They regulate or shut off flow through a piping system using a ported plug connected to the handwheel/actuator via a stem. The plug, cylindrical or conical in shape, swivels 90 degrees to constrict or allow liquid flow. There are two versions of this valve: lubricated and unlubricated. The former uses lubricant between the valve and the plug, while the latter uses a polymer sleeve to reduce friction and improve sealing. Advantages include versatility in size, quick operation, efficient shut-off, and low-pressure drop.
Factors to Consider When Selecting Valves for Chemical Industries
- Resistance to corrosion.
- Temperature and pressure levels.
- Construction material: corrosive insulated material is preferable.
- Type of medium: some valves are meant for clean liquids, while others can handle solids and slurry.
The above information is intended to provide insights into different types of valves used in the chemical industry and the factors to consider when selecting them. Choosing the right valve is crucial to ensuring the efficient handling of chemicals and minimizing potential risks. If you require further modifications or have specific requests, feel free to let me know.