How Much Do Leaky Pressure Relief Valves Cost?
In industrial processes that frequently operate under pressure, pressure relief is often achieved through the use of Pressure Relief Valves (PRV). The use of these devices is preferred because they ensure the safe operation of processes when they re-close after the application of incidental overpressure. As essential security devices, the best performance of these critical PRVs is outstanding. The Pressure Relief Valve is designed to contain pressurized media in a closed system, but the reality is that most PRVs will exhibit some leakage. API 576 is the only industry standard currently available that defines acceptable levels of leakage through conventional PRVs. Where the primary purpose of the PRV is to protect the installation against unacceptable overpressure, leakage (even when minor) can lead to additional costs and disruption to production.
Where critical components of the PRV suffer from damage from repeated exposure to corrosion or wear, significant investments will need to be made to ensure that replacement parts are readily available. Where pressure relief valves discharge into a common header system, cumulative and sustained leakage of all connected PRVs may cause a base load on the emergency response system or equipment, increasing the need for maintenance. With the increase in base load resulting from the leak, it is necessary to evaluate the capacity increase of the emergency response system. Last, but not least, increasingly stringent emission restrictions with associated penalties are encouraging the industry to reduce ongoing leakage in all devices, including PRVs.
These problems can be easily solved through the use of insulation with a rupture disc from Zook, known as ‘combined use’. By using the rupture disc assembly on the inlet side, any leakage and risk of corrosion or wear on critical PRV components will be eliminated. The rupture disk forms a sealed layer that will burst when the specified overpressure is reached, allowing the PRV to evacuate. By not continuously exposing the PRV to the product in process, significant reductions in initial investment can be achieved through the selection of less costly construction materials for PRVs. A rupture disk made of suitable corrosion-resistant material will save the PRV from exposure to such a substance. By adding a rupture disk to the PRV outlet, incidental back pressure is kept away from the internals of the PRV valve, thus preventing the springs from balancing.
By using the rupture disk to isolate the valve, the characteristic product leakage in the PRV is significantly reduced, the main load on the material handling system on the outlet side (drying drum, neutralizer, etc.) is also reduced, which avoids unnecessary investments and emission penalties. It will reduce downtime, emissions, corrosion, capital investments, maintenance costs and spare parts stock, while keeping the reliability of the safety system at the highest level. Simply this process can help keep the cost of ownership of the pressure safety system under YOUR control.
