How to eliminate emissions from pressure relief valves
Emission control is essential to protect employees , communities and the environment from harmful chemical leaks and to protect the business from significant fines .
By Michael Hunt , Business Development Manager , Fike
An effective way to reduce overall leakage is to instal rupture discs upstream of pressure relief valves .
While a certain level of fugitive emissions is allowable , various governmental agencies , including the European Emissions Trading System ( EU ETS ) and the US Environmental Protection Agency ( EPA ), impose fines for emission levels above acceptable limits . Furthermore , these fines are publicised , which may negatively impact the company ’ s public image at local , national , and global levels . Most industrial processing companies and their operators seek to implement simple , non-invasive methods to control their emissions to avoid these consequences .
Isolation of leaking pressure relief valves
One of the most common emission sources throughout the processing industry is pipe connections through the use of flanges and gaskets . Improper design and installation , incorrect selection of gasket materials and bolting , and general wear and tear of these connections are causes of potential fugitive emissions . However , another often overlooked source of emissions is the leakage or ‘ weeping ’ of process media through pressure relief valves . Most spring-operated pressure relief valves rely on special metal-tometal sealing surfaces to achieve leak tightness .
Inevitably , some leakage occurs as the operating pressure approaches the valve ’ s set pressure . Leakage also occurs over time as valve components wear , and leakage causes more wear , leading to increasing leakage rates .
Rupture discs
Many industrial processing companies have found that an effective way of reducing overall leakage is by installing rupture discs upstream of pressure relief valves . Rupture discs , or bursting discs , are effectively leaktight , single-use metallic pressure relief devices engineered to open when the process pressure reaches the disc ’ s set burst pressure . In these upstream assemblies , the process media only reaches isolated pressure relief valves when the rupture disc activates . The combination of pressure relief valves and upstream rupture discs will largely eliminate the continuous emissions from the valve . At the same time , the safety of the installation against overpressure conditions remains at the required level .
Additional benefits of upstream rupture discs
In addition to emission control , installing rupture discs upstream of pressure relief devices may
40 Valve World November 2022 www . valve-world . net