Selecting the correct safety valve is essential for protecting boilers, pressure vessels, pipelines and process equipment from excessive pressure. A suitable valve must match the operating conditions of the system while providing reliable discharge capacity during an overpressure event. The first step…
Selecting the correct safety valve is essential for protecting boilers, pressure vessels, pipelines and process equipment from excessive pressure. A suitable valve must match the operating conditions of the system while providing reliable discharge capacity during an overpressure event.
The first step is to identify the protected equipment’s maximum allowable working pressure and required set pressure. The safety valve set pressure must comply with the applicable design code and should not exceed the pressure limit of the protected equipment. Engineers should also confirm the expected relieving pressure and required discharge capacity.
The process medium is another important factor. Steam, compressed air, gas and liquid applications have different flow characteristics and may require different valve designs. The medium’s corrosiveness, cleanliness and toxicity should also be considered when selecting body, trim and sealing materials.
Operating temperature affects both material selection and valve performance. Carbon steel may be appropriate for many general industrial applications, while stainless steel, alloy steel or special alloys may be required for corrosive, cryogenic or high-temperature service.
Back pressure must also be evaluated. Conventional spring-loaded safety valves are commonly used where back pressure is limited and stable. Balanced-bellows valves can provide better performance when variable back pressure is present. Pilot-operated safety valves may be suitable for high-pressure systems, applications requiring tight sealing or installations where the operating pressure remains close to the set pressure.
Connection type, inlet and outlet size, installation orientation and discharge piping should be reviewed before placing an order. Excessive inlet pressure loss or poorly designed outlet piping can reduce valve performance and create operational problems.
Applicable standards and certification requirements should be confirmed early in the selection process. Depending on the project location and application, requirements may include ASME, API, CE/PED or other national and industry standards.
A complete safety valve inquiry should include the process medium, set pressure, operating pressure, relieving temperature, required capacity, connection standard, material requirements and applicable certification. Providing complete operating data allows the manufacturer to select and size the valve more accurately, reducing the risk of incorrect specification and unnecessary project delays.