Choose the right safety valve
Safety valves ensure that overpressure does not occur in the system. VIMAB can help you select and maintain your safety valves.
Safety first!
Keep an eye on the pressure
Safety valves are there to protect life and property. In the early days of industrialisation, it was not uncommon for boilers to explode, which led to the introduction of safety valves. The basic problem then is the same today - a pressurised system must be safe to operate.
The medium in the process is not only pressurised, it can also be at high temperature and hazardous. It can, for example, be corrosive. The equipment is designed to withstand a certain pressure that must not be exceeded. If a higher pressure occurs, it can be both dangerous and cause emissions that are harmful to the environment. High pressure can also damage the system and cause costly production stoppages.
The safety valve makes the installation safer by releasing part of the medium at overpressure. When the pressure has returned to normal, the valve is closed again.
The cause of overpressure can be a blocked outlet in the system, overheating leading to rapid expansion of �nga, uncontrolled thermal expansion of the medium, a chemical reaction in the medium, or a mechanical failure in the system.
When are safety valves used?
The safety valve should normally never be used. It is a last lifeline to ensure that the installation does not fail.It is therefore important to check at regular intervals that the safety valve is still working.
All industries with processes need safety valves. These include the oil industry, chemical manufacturing, pulp and paper, power plants, food and pharmaceuticals, to name but a few.A safety valve may also be referred to as a pressure relief valve, pressure relief valve or pressure safety valve.
How to choose the right safety valve?
Safety valves must be used to meet the requirements set by law. In addition to meeting legal requirements, the selected valve must of course also be suitable for the process requirements. In addition, you must take into account the technical standards ? ISO if the process equipment is designed according to European requirements or API/ANSI if they are American, which is often the case in the oil industry.
Choosing the right safety valve can be complicated. Please call us at VIMAB and tell us about your application, so we can help you choose the safety valve that best suits your particular process.
How to maintain safety valves?
Once the safety valve has been installed, you must ensure that it continues to function. In some applications, maintenance is needed more often than in others. This can happen, for example, if the medium is sticky, as can be the case with thick oil in oil refineries, or lye in paper mills.
It can also happen that a process is changed. Since the equipment is designed for a certain pressure, temperature and medium, it is possible that the safety valve is no longer suitable for the application. If there is a fault with the valve, or if it is incorrectly dimensioned, it may not open at the correct pressure. This is fraught with danger.
Who is responsible for ensuring that the safety valve works?
It is the facility owner who is responsible for ensuring that the ongoing maintenance work is carried out. Ensuring the functionality of the safety valve is a collaboration between you as the facility owner; VIMAB as the service partner; and the inspection body, which must be accredited. VIMAB has long experience of working with accredited inspection bodies and can help to resolve any questions that arise.
The work carried out by VIMAB is inspected by the inspection body. The regulations can be found in AFS 2017:3 on pressurised installations. The safety valve can be exercised during operation to ensure that it still works. However, this is associated with a certain risk and without training you can do more harm than good..Vimab has both the right knowledge and trained staff. VIMAB can also organise training for your staff.
Types of safety valves
High-lift safety valves are the most common type of safety valve. It provides a quick lift with a small increase in pressure. They are used for venting media that can be compressed, such as vapour and gas. They are designed to open as quickly as possible. The outlet is larger than the inlet, so that the medium has the opportunity to expand.
A proportional safety valve opens gradually as the pressure rises. It is used for hot water. Since water cannot be compressed, it does not need the same sensitivity as in a gas system.
An additive-loaded safety valve provides faster and more controlled opening and closing. The additive consists of compressed air that controls a pneumatic actuator, which is opened and closed from an external control head. Because the valve is controlled very precisely, the system's operating pressure can be close to the valve's opening pressure.
The safety valve must be completely closed during normal operation. The material of the seal is chosen with regard to the medium. There is a wide range of polymer materials with different properties and resistance. If the medium is freezing or very hot, such as steam, a hard sealing valve is used that seals metal to metal.