Operation & Maintenance of Power Plants 


Reclosing pressure relief devices, commonly referred to as safety relief valves (SRV), pressure relief valves (PRV) or relief valves (RV), are designed to provide opening for pressure relief at the selected set pressure, allow for the overpressure to evacuate and will then reclose when the pressure has dropped below an acceptable level.


discs, holders and customer pressure relief devices which are compliant with global code regulations and designed to meet or exceed industry requirements for performance, reliability, and quality. On a large number of occasions rupture discs are selected to be used in combination with relief valves. Such combinations can be either in parallel or in series, both of which offer to the user the choice of a combination of features which provides the ‘best of both worlds’.


l Case 1: Rupture Disc in Parallel with Relief Valve. When used in parallel, the main objective of the designer/user will be to allow for the relief valve to handle the overpressure situation, bleed the pressure until an acceptable pressure is achieved and allow for the process to continue. Where the overpressure cannot be effectively


reduced by the relief valve, the pressure may continue to rise until the (higher) set pressure of the rupture disc is reached. Upon activation the rupture disc will provide an additional/back-up relief path for the overpressure, resulting in a safe situation.


Fig. 2. Steam-driven energy cycles are inherently linked with pressure risks in the (high-pressure) steam circuit equipment such as steam condensers, heat exchangers and boilers.


Rupture or bursting disc devices are often preferred to achieve instantaneous and unrestricted pressure relief (both overpressure and vacuum pressure). Tese disks are designed to provide a leak-tight seal within a pipe or vessel, until the internal pressure rises to a predetermined level. At that point the bursting disc ruptures, preventing damage to the equipment from overpressure. Tey consist of a calibrated metallic membrane which will rupture when the set pressure is achieved.


Discharge of pressure After activation the membrane will remain open resulting in a complete discharge of the pressure from the installation. Fike offers a complete line of cost-effective bursting


l Case 2: Rupture Disc in Series with Relief Valve. Rupture disc devices may be installed upstream or downstream of relief valves, each geometry offering its particular benefits for the user. A rupture disc upstream of relief valve prevents plugging, corrosion or leakage and allows for in-situ testing. A rupture disc downstream of relief valve prevents


corrosion, fouling or sticking of the relief valve: prevents variable superimposed backpressure affecting relief valve; detect opening or leakage of relief valve.


Conclusions Pressure relief solutions are common in industry processes, to assure that the investments are safe and a safe working environment is presented to the employees.


Te use of rupture discs in combination with


relief valves can be done in several combinations. It offers a wide range of benefits to the user and for the environment, cost reduction, emission control, higher safety and reliability levels and improved performance of the plant safety systems are a direct result. Process system designers need to evaluate the individual effects and make a selection of what geometry applies best for the individual plant requirements. In most applications the combined solution of


rupture discs and relief valves offer customers more value for more benefits – a true definition of ‘more for more’. l


Fig. 3. Rupture or bursting disc devices are often preferred to achieve instantaneous and unrestricted pressure relief.


For more information ✔ at www.engineerlive.com/ipe Roger Bours is Manager Pressure Relief, Fike Europe, Herentals, Belgium. www.fike.com www.engineerlive.com 25


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