Unlocking Safety: The Vital Role of Rupture Discs in Flammable and Corrosive Processes

There are a number of mechanical and operational factors to take into account while installing rupture discs in order to decrease the possibility of leaks and fugitive emissions.

Within chemical processing plants and oil refineries, overpressure relief systems made up of rupture discs and relief valves are essential for preventing damage and harm. When installed, maintained, or specified incorrectly, these systems have leakage or fugitive-emission issues. Such leakage problems may have negative effects, such as contamination, corrosion, product loss, and clogging. Other, more severe outcomes could include putting workers and the public in risk, paying fines or cleanup costs imposed by regulatory bodies, and losing output as a result of unscheduled shutdowns.

Less or no leakage occurs through the intended overpressure relief path thanks to rupture discs. However, adequate device sizing and installation are necessary to prevent leaking to the atmosphere between the rupture disc and holder. Additionally, meticulous examination, appropriate cleaning, and routine maintenance of components are required. Users can reduce leakage and fugitive emissions in their plant’s overpressure relief systems by understanding the various rupture disc technologies, assembly types, and sealing mechanisms used.

Use of Rupture Discs for Relief Valve Isolation

Rupture Disc and Safety Valve in Series

The isolation of pressure relief valves is the most typical application for rupture discs. In order to provide pressure to sealing surfaces and keep the process media contained, pressure relief valves use springs or other mechanisms. When there is an overpressure occurrence, the sealing surfaces are forced to split, releasing process fluids up until the predetermined pressure is reached. The remaining pressure is now contained by the sealing surfaces after the relief valve shut closes. Without rupture discs, at operating pressures close to or above 90% of the set pressures the relief valves start leaking. This case can be serious for applications involving flammable media particularly Hydrogen gas. Hydrogen molecules are very small and more likely to leak as compared to any other gas. Hydrogen is also one of the most explosive gases. It can readily explode after leaking through the safety valve even at lower concentrations and at ambient temperature. 

Without rupture discs, relief valves frequently leak, especially if operating pressures are too close to the relief valve’s fixed pressure. Product loss, corrosion of the sealing surfaces, sticking, and increased valve wear are all effects of relief valve leakage. System shutdowns for maintenance will typically result in more frequent intervals due to the increased stress on the relief valve. Plants can save money by avoiding unanticipated maintenance shutdowns by installing rupture discs under pressure relief valves.

Rupture discs can be easily made in a range of materials for compatibility with most process media, open considerably more quickly than relief valves, and create a leak-tight seal. Compared to relief valves, they can be made from pricey, corrosion-resistant alloys more quickly and economically. The rupture disc stays open until it is replaced once it has been activated. Plants can take advantage of the benefits offered by each technology by installing a rupture disc on the downstream side of a relief valve.

A relief valve’s sealing surfaces can be maintained by rupture discs, which also serve to keep the valve in excellent shape. The relief valve will reliably reseat itself in the case of an overpressure scenario without danger of corrosion or product buildup. Rupture discs acting as a first line of defence will assist the relief valve last longer, go longer between maintenance intervals, and cost the overpressure relief systems less overall.

Combining the two technologies for overpressure relief adds another level of complexity that must be taken into account to assure success. Boiler and Pressure Vessel Code (BPVC) XIII-1 UG-127(a) (3) (-b) (-4) of the American Society of Mechanical Engineers (ASME) mandates that the area between the rupture disc and the relief valve be checked for pressure fluctuations. Due to the fact that rupture discs are differential pressure devices, their burst pressure is influenced by pressures both upstream and downstream of them.

Pressure builds up between the rupture disc and the relief valve whenever a rupture disc has a little leak as a result of misuse, corrosion, or other damage. The actual burst pressure of the disc is effectively increased by a pressure buildup downstream of the rupture disc. The disc is activated at a pressure higher than the disc’s targeted burst pressure as a result of the added pressure. Therefore, it is crucial to check the pressure in this area. This is usually done by utilising a pressure gauge or a monitored pressure switch.