The petrochemical industry is vast and not just limited to the production of oil and gas. Petrochemical plants make a myriad of products, including detergent, dyes, food additives, plastics, sneakers, and much more. The industry involves the employment of extreme pressures and temperatures to produce different commodities. It requires sophisticated engineering, and valves that control material fluids are essential to its various operations. No matter the type of valve used, it is vital that the valve does not cause the leak of hazardous materials.
What Is a Valve?
A valve is a mechanical device that is used for starting, regulating, or stopping flow. Valves are commonly used to block pipes, either partially or entirely, in order to alter the quantity of fluid that passes through them. For example, when turning on a faucet, you’re causing a valve to open that lets pressurized water out of a pipe. Similarly, when flushing your toilet, you are opening two valves: the siphon that enables water to empty into the toilet bowl, and the ball valve (or ballcock) that lets more water into the tank ready for the next flush.
Valves don’t only regulate liquids; they also control gases. If you have a gas stove, the controls that turn the gas up or down on your stovetop are valves. When you raise the heat level, you’re opening up a valve that will let more gas flow in through a pipe. There are also valves inside the cylinders of your car’s engine. When the engine runs, these valves open and close several times per second, admitting air and fuel and allowing burned exhaust gases to escape.
- The Importance of Seals – Valves are typically manufactured from metal or plastic and they have several different components. The outer part of a valve is called the seat and it often has an outer casing of solid metal and an inner seal made of a softer material such as rubber or plastic. This enables the valve to make a closure that’s absolutely tight. When valves are switched off, it’s critically important that no liquid or gas is allowed to escape.
Valves Used in the Oil and Gas Industry
Equipment used in the petrochemical industry is often required to operate under challenging conditions. This means that valves in this equipment must be able to function well under severe operating conditions. They must meet critical safety criteria and be dependable in remote locations. Valves must meet critical standards for reliable pressure, flow control, and complete shutoff. All production and pipeline components, including valves, are expected to be long-lasting to maximize return on investments. The following is an overview of three common types of valves used in the petrochemical industry.
- Control Valves
As the name implies, a control valve is a device that controls the flow of liquid or gas. Control is achieved by a valve opening or closing fully (on/off), or partially opening and closing (modulating). Modulating valves change the size of the opening through which the liquid or gas is flowing, and they are also able to fully open or close. It should be noted that a control valve all by itself is unable to do anything. In order to open or close, the valve actuator needs a command from an exterior source. This signal is provided by one of the following, depending on whether the valve is actuated pneumatically or electrically.
- Pneumatically actuated: a liquid level controller or a pneumatic pilot.
- Electrically actuated: a liquid level controller or an electrical pilot.
Types of Control Valves:
- Modulating Valves – These are linear valves with a stem in the center. They can operate to modulate control and also where on/off application is needed.
- On/Off Valves – Valves that only provide turn on or shut off service include ball valves, butterfly valves, and gate valves.
- Isolation Valves
Isolation valves are used to open and shut the flow of fluid or gas coming from a pipeline. This type of valve is typically used for safety and maintenance purposes in the petrochemical and other industries. Innovations in various applications of isolation valves in advanced oil and gas production techniques and pipeline processes are leading towards new developments and higher performance in these valves. Isolation valve types include ball valves, butterfly valves, check valves, gate valves, globe valves, and plug valves.
- Pressure Relief Valves
Pressure relief valves are arguably the most important safety devices in any petrochemical production facility. They ensure that pipes, fittings, other valves, and pressure vessels can never be subjected to pressures higher than those they were designed for. Relief valves are designed to open fully and rapidly and be adequately sized to handle the total flow of liquid or gas that has the potential to lead to a situation of too much pressure. The valves relieve the pressure by routing the material stream to a safe location where it can be burned or vented to the atmosphere.
As long as pressure, temperature, and level control devices are operating appropriately, a safety system does not need to operate. However, if the control system malfunctions, then safety switches sense the problem, and the inflow can be shut off. If the safety switches don’t work, then relief valves are there to protect against overpressure. Pressure relief valves are vital because safety switches do fail or may be bypassed for operational reasons. Moreover, even if safety switches work correctly, shutdown valves don’t take effect immediately. This means that pressure may be stored in vessels upstream that can then lead to overpressure in downstream equipment while the system is shutting down. The bottom line here is that relief valves are essential to the safety of petrochemical production and applications.
What to Do if Valves Need Repair
The use of the appropriate petrochemical valves is crucial for both efficiency and safety. Wagner Energy Services is an oil field service company and your best resource for valves and valve service. Our oilfield valve division supports your complete control, isolation, and pressure relief valve needs throughout West Virginia, Pennsylvania, and Ohio. Our professionals stand ready to serve your complete valve repair and maintenance needs 24/7. Please contact us for more information.