Control Valve Handbook

This chapter discusses some specialty valves, special applications, and control valve modifications useful in controlling them, designs and materials for severe service, and test requirements useful for control valves used in nuclear power plant service. Examples include high-capacity control valves, low-flow control valves, high-temperature control valves, and more.

Superheated steam provides an excellent source of energy for mechanical power generation. However, in many instances, steam at greatly reduced temperatures, near saturation, proves a more desirable commodity. This is the case for most heat−transfer applications. Precise temperature control is needed to improve heating efficiency, eliminate unintentional superheat in throttling processes, or to protect downstream product and/or equipment from heat related damage. One method to reduce temperature is the installation of a desuperheater.

This chapter outlines in detail proper control valve storage and protection, installation techniques, as well as predictive maintenance. Additionally, this chapter will discuss service and repair parts available for maintaining several types of control valves. With proper control valve operation, you can achieve high yields, quality products, maximum profits, and energy conservation.

This chapter provides a detailed breakdown of isolation valve types and actuators. Valve types that are discussed within this chapter include, but are not limited to gate valves, globe valves, diaphragm valves, and more. Even though there are dozens of valve varieties to choose from, the primary purpose of valves remains the same; that is to stop or start flow, or to regulate flow. This chapter will also explore the role each of these control valve types plays within the process control system.

A solenoid-operated valve, commonly known as a solenoid valve, (SOV) is an on/off electro-magnetic valve that is controlled by a discrete electrical signal from a control system. In process control applications, SOVs are generally used to pressurize or de-pressurize on/off actuators. Control valve applications will typically use a solenoid valve between the digital valve controller and the control valve. 

A safety instrumented system is a safety system independent of the process control system. It has separate sensors, valves, and a logic solver. Its only role is safety. No process control is performed in this system. Operator intervention and the safety instrumented system layers are designed to prevent a safety-related event. If a safety-related event occurs, there are additional layers designed to mitigate the impact of the event. This chapter also covers safety standards, probability and partial stroke testing, and more.