Selecting the suitable valve when designing a fluid control system that operates under high-pressure conditions is paramount. Selecting the appropriate valve becomes even more challenging as there are several parameters to consider, such as valve material, leakage of hazardous fluid, and more. In addition to these parameters, ensuring the safe operation of the valve to protect personnel and the environment is of utmost importance. These factors are in addition to the general characteristics of a valve that make it suitable for a particular application. Altogether, selecting a high-pressure valve can be rigorous and requires careful consideration of all relevant factors.
When designing a system that includes high-pressure valves, understand what qualifies as a “high-pressure valve.” While there is no industry-standard definition for a specific Bar or psi threshold that denotes a high-pressure valve versus a medium- or low-pressure valve, engineers generally consider any valve operating above typical industry conditions as “high-pressure.” Therefore, to ensure optimal performance and safety in your system, it’s essential to keep this in mind and design accordingly. Therefore, let’s delve into the crucial considerations when designing a high-pressure valve system.
The definition of high pressure may vary depending on the industry, but the principle of selecting appropriate equipment remains consistent. Whether you’re choosing high-pressure valves for domestic applications at 6 bar or for oil and gas processes at 6,000 bar, safety should always be a top priority. These environments are not designed for regular operation at such extreme pressures, and proper selection is crucial to ensure safe and efficient operation.
Understanding the environment’s normal operating pressure is crucial when selecting high-pressure valves for an application. This knowledge allows us to effectively identify the five most important factors to consider while choosing a high-pressure valve.
Six Valve Pressure Factors to Consider
Ensuring safety is paramount and cannot be treated as a mere parameter to be selected. Instead, it is the result of careful attention to other essential parameters. To guarantee a safe and efficient operation of a high-pressure valve, we have identified five critical parameters that must be met. By adhering to these parameters, you can rest assured that your valve will function optimally and safely.
1. Maximum Operating Pressure
The maximum operating pressure of a valve is a crucial specification that determines the pressure limit beyond which the manufacturer cannot ensure the valve’s safe and effective operation. This applies to all types of valves, including high-pressure valves. When choosing a high-pressure valve, it’s essential to consider the operating pressure of your process stream and the potential maximum pressure limit when a pump is set at maximum head against a closed valve downstream. Your selection criteria for high-pressure valves should be based on the worst-case operational scenario.
2. Operating Temperature
High-pressure valves are crucial components in many industrial applications. To ensure efficient and safe operation, it is essential to consider both the pressure specification and the maximum operating temperature of the valve. A high-pressure valve with a temperature limit that matches your process operating temperature will ensure optimal performance and longevity. Look out for this critical feature when selecting a high-pressure valve for your application.
The durability and reliability of high-pressure valves depend primarily on the quality of the materials used for their construction. Pressure, temperature, wear, and corrosion resistance are critical in determining the appropriate material for valves and their components. It is also essential to consider material compatibility between the fluid, additives, and valve to ensure optimal performance. Industrial valve manufacturers provide incompatibility charts that offer a comprehensive list of fluids compatible with specific valve materials, enabling informed decision-making in valve selection.
The valve body and seat are vital components of any valve, and choosing the suitable material is crucial for its performance and longevity. Ductile iron offers shock absorption and affordability but falls short in corrosion resistance. Brass or bronze are better options for corrosion resistance but may not be suitable for high-pressure applications. For optimal performance in high-temperature and corrosive environments, 316 stainless steel is a top choice due to its impressive corrosion resistance and high tensile strength. Additionally, valve bodies can be made of monel or Inconel for excellent corrosion resistance and stability at high temperatures. While these materials may be pricier than iron, brass, or bronze, their superior performance makes them a worthwhile investment in the long run.
Valve components such as gaskets, seals, and packing require materials that can withstand high pressures and temperatures. Polytetrafluoroethylene (PTFE) is often used due to its low friction properties, while materials like polyurethane, Viton, or polyetheretherketone are preferred for their durability and chemical, and corrosion resistance. For high-pressure applications, it’s best to seek advice from a valve expert to select the proper valve body and seat material.
4. Connection End Type
In high-pressure applications, the choice of end connection is critical in preventing leaks. While threaded end connections are ideal for smaller pipe diameters (less than 2 inches), they can be challenging to seal under high pressure for larger sizes. However, threaded connections are still advantageous when periodic valve maintenance is necessary.
Welded connections have become the preferred choice for high-pressure applications because they provide a leak-proof seal. They are also commonly used in hazardous fluid systems. Unlike other connection types, welded-end connections are permanent and can withstand the most demanding conditions. High-pressure valves can have two types of welded-end connections: socket-welded and butt-welded.
High-pressure valves were more significant than 4 inches and could be easily connected to pipes using flanged connections. These connections are widely used in industrial applications, particularly those involving high pressure. Flanged connections offer a reliable seal, ease of maintenance, and simple installation. Several types and styles of flanged connections are available, which are standardized under DIN 1092-1, ANSI/ASME B16.5, and SAE J518.
5. Leakage Tolerance
When selecting a high-pressure valve, it’s essential to consider the amount of leakage that can be tolerated based on your application. If your process fluid isn’t hazardous, there may be some leakage tolerance that can help you avoid unnecessary costs associated with zero-tolerance valves. Valve leakage can be influenced by the type of end connection and the packing seal that holds the shaft to the valve’s body. The amount of leakage tolerance is pressure-dependent, so it’s essential to refer to charts provided by high-pressure valve manufacturers. To ensure compliance with industry standards, refer to MSS standard SP-61 and ANSI standard 70-2, which define allowable leakages and leakage classifications for high-pressure valves.
6. Size Availability
High-pressure processes require pipes that can withstand the pressure without breaking, which can be costly. As a result, smaller pipe diameters are often used. However, it’s important to note that the industry’s high-pressure valves are also typically small. So, when designing your process, it’s crucial to ensure that high-pressure valves are available for the piping dimensions you plan to use.
What Are Types of High-Pressure Valves?
Valves used for high-pressure operations require specific characteristics to ensure optimal performance. These characteristics can be defined by two key factors that differentiate between types of valves suited for high pressure.
- If a pressure-balancing system is not installed, high-pressure valves must operate under extreme pressure differentials between their sides. This demands the use of specialized high-pressure valves.
- Preventing leaks in high-pressure valves is critical to ensure proper functioning. Valves must close effectively, even under high-pressure differences, to prevent loss or damage.
Given these qualities, high-pressure valves are frequently of the five varieties listed below:
- Globe valve
- Plug valve
- Needle valve
- Ball valve
- Gate valve
Valves play a crucial role in high-pressure environments, serving a variety of functions such as flow control (modulating and on/off), safety, over-pressure protection, check valves, isolation, flow throttling, and particular purposes. Accordingly, these valves undergo specific modifications to meet the unique demands of such environments, including non-rotating stems, packing and sealing materials that minimize contact with the process fluid, and a positive shutoff mechanism. These modifications ensure that the valves operate reliably and effectively in high-pressure settings.
High-pressure valves are crucial in various industries and applications, including oil and gas exploration, petroleum refining and distribution, chemical and petrochemical processing, water supply, wastewater management, food and dairy, aerospace, subsea operations, military, and water jet cutting and cleaning. These valves are critical components that help regulate and control the flow of fluids and gases under high pressure, ensuring efficient and safe operations in various settings.
Flow Control System Considerations
Designing a flow control system for a high-pressure environment is a task that requires careful consideration of several factors. To ensure a safe and functional working valve at high pressure, it is essential to consider the maximum operating pressure, valve material, connection end type, leakage tolerance, and size availability. It is worth noting that not all valves are the same when it comes to high-pressure operations. Specific designs may perform better than others, so reading the manufacturer’s recommendations and specifications is crucial before deciding on a suitable high-pressure valve for your system.
You can guarantee that your flow control system is optimized for high-pressure conditions and operates safely and effectively by taking the time to evaluate these considerations and selecting the proper valve.
