SAFETY IN THE PLANT
‘BREATHES’
RUPTURE DISC THAT
To increase equipment safety and reliability, a novel rupture disc technology activates at a set burst pressure, but can ‘breathe’ to relieve minor pressure fl uctuations
n industry, one-time-use rupture discs have long provided pressure relief on hydraulic and pneumatic equipment, serving as an eff ective passive safety mechanism to protect against potentially damaging overpressure or vacuum conditions. Each disc is typically designed to burst, rapidly changing from a leak-tight seal to a full diameter fl ow opening when a predetermined over or under pressure event occurs. At that point, the rupture disc needs to be replaced. Rupture discs are a proven solution,
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particularly for the protection of certifi ed pressure vessels whose protection is driven by the European Pressure Equipment Directive (PED) threshold of 0.5 bar and above and American Society of Mechanical Engineers (ASME) threshold of 15 psig and above. Demand for this type of sealed,
fl uid-containing safety equipment is increasing for aseptic products in the health care, liquid food, and cosmetics industries and other applications where service pressures and even atmospheric pressure are much lower. Rupture discs are a critical component to seal fl uid within the container under normal operating conditions and protect against overpressure
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The new requirement is for a rupture disc that will allow air fl ow in and out of a sealed container when a small pressure diff erential arises without the disc bursting
caused by such events as external fi re or an unexpected chemical reaction. Even noncombustible fl uids can lead to overpressure conditions as they reach and exceed their boiling point. With atmospheric storage equipment that is sealed, a particular challenge is that
An integrated assembly is certifi ed to perform at the desired set pressure
signifi cant internal pressure fl uctuations can also occur because of ambient temperature swings, particularly for vessels located outdoors or otherwise exposed to daily temperature excursions. Consider that at common equipment application temperatures (-400° C to 80° C), the shift in pressure in a sealed container can range from -3 to 3psi. “Although many fl uids are stable under atmospheric pressure, when placed in a closed container even normal fl uctuations in ambient temperature or equipment operation can generate overpressure (as temperature rises) or vacuum (as temperature falls),” says Geof Brazier, managing director of BS&B Safety Systems’ Custom Engineered Products Division. “Over time, this can compromise simple metallic and non-metallic container integrity due to fl ex and fatigue, leading to potential quality and maintenance issues and ultimately uncontrolled rupture of the container.”
BREATHEABLE DESIGN In response, an innovative new “breathable” rupture disc technology has been developed that provides overpressure and vacuum
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