Rupture Discs: your most important safety device
Rupture or Bursting Discs, a non-reclosing, fail safe device. Probably the most misunderstood and least appreciated safety device used in systems where pressure or vacuum are present and where excess pressures or vacuum may need to be controlled and relieved when conditions exceed the safe design parameters.
The first discs were very simple flat pieces of metal, weakened to open, sometimes with very little accuracy or predictability, at a supposedly fixed pressure. Over the years the technology employed in controlling pressures in the various types of oil, gas, petrochemical and other downstream industries has improved and developed to high levels of safety, mostly through the use of electronics and pneumatics to maintain a safe working pressure regime in the various plants.
In addition, the development of safety valves has also moved forward, again raising the safety level to one where many design and plant personnel lost sight of the most important safety device in the plant, the Rupture Disc.
Today operators and end users have been lulled into a false sense of security that the design engineers and system process/instrumentation designers have covered all the possibilities with sophisticated control and monitoring systems, nothing can go wrong so why do we need a Rupture Disc? There are many reasons why we need Rupture Discs these include:
- Fast opening times, typically < 2ms, reacts to sudden pressure rises far faster than any valve
- Full bore opening, unlike safety valves where the orifice restricts the flow
- 100% isolation of process fluids, no leaks until the disc opens
- Isolate safety valves from corrosive process media when installed upstream of the safety valve, can also be used downstream to protect the outlet
- Prevents rogue emissions, blockage of the safety valve and can be used to pop test the safety valve in-situ
The same false thinking and a lack of understanding of Rupture Discs has led over many years to the wrong belief that Rupture Discs are a problem because they open and then have to be changed. The whole point of a properly designed Rupture Disc is that it will ONLY open when the design pressure and temperature are reached or exceeded.
So why do so many of the design engineers get it wrong when they set out to do the FEED work? Mainly because they were never taught or had an explanation of what a Rupture Discs does and does not do. They think that if they understand safety valves then the same design and selection process can be applied to Rupture Discs, it does not work.
Rupture Discs selection is based on the information given in the datasheet of the RFQ or tender, sometimes this is minimal, where in reality the volume of information needed is much higher to ensure that the Rupture Disc is engineered and manufactured to meet the needs for that application. As many as 53 different points are needed to ensure that the disc is engineered to the full specification so it will operate correctly, on average only 8 points are given to make the design. There is more emphasis given to painting specs, packaging, how many copies of paperwork, the inspection etc. than to the specification of the Rupture Disc itself.
To recap, a Rupture disc and its holder are your most important safety device, as long as it has been specified correctly in the design stage. It is failsafe, whatever else goes wrong a properly designed and engineered disc opens at its set pressure. Electronics, pneumatic and mechanical devices can fail, human error can cause operational errors in the pressure system, the Rupture Disc still opens, your best device to protect your plant.
I T E L S T O R Y
REMBE has invested in technology advances in Rupture Disc design using laser technology and advanced engineering to produce the most reliable and cost effective Rupture Discs available. It doesn’t stop there, REMBE is 100% German and from our headquarters and manufacturing plant in Brilon, Germany REMBE continues with our in-house R&D to push the engineered Rupture Discs and associated technologies further forward.