Tuesday, November 29, 2016

Safety Relief Valves: The Basics

Safety relief valves by Kunkle
Safety relief valves by Kunkle
The safety relief valve is used to control or limit the buildup of pressure in a piping system, tank or vessel. Uncontrolled pressure can occur because of valve malfunction, process system upset, instrument failure, or fire.

In generally accepted practices, pressure build-up is relieved by allowing the fluid to flow from an alternate path in the piping system. A safety relief valve is engineered so that it opens at a predetermined pressure setpoint to protect vessel, piping or ancillary equipment equipment from being subjected to pressures that exceed their design limits.

When process pressure is exceeded, a safety relief valve becomes the “weak link”, and the valve opens to divert a portion of the fluid to another path. The diverted liquid, gas or liquid–gas mix is usually routed through a piping system to a process where it is safely contained or burned off via a flaring system. Once the liquid or gas is diverted, the pressure inside the vessel drops below the safety relief valves' re-seating pressure, and the valve closes.

The Data Supplement below presents a wealth of technical information on Kunkle relief valves.