Fragmentation occurs when a rupture disc shatters into multiple fragments upon bursting. Older rupture disc designs were traditionally all fragmenting. Unscored, forward-acting (also known as ‘tension-loaded’) rupture discs of any type of metal can be prone to fragmentation. Graphite rupture discs will always fragment, graphite being a very brittle material.
This high-speed video shows what happens when three types of rupture disc burst:
As you can see, the graphite disc immediately shatters into tiny pieces. The flat metal composite disc, however, does not fragment. The scoring around the periphery of the disc helps control the burst and prevent fragmentation. The reverse-acting design and the peripheral scoring of the third disc prevent fragmentation. The entire disc lifts away from the ‘hinge’ at the top but does not release any fragments into the downstream pipework.
When a rupture disc with a fragmenting design bursts, the pieces of disc enter the downstream pipework along with the contents of the vessel or piping. At best, these fragments contaminate the product and may be difficult to remove; at worst, they can clog up, foul or damage downstream pipes and valves, causing safety issues and necessitating a shutdown for repair, cleaning and maintenance. To avoid these issues, ASME states that any discs used below a pressure relief valve or safety valve must have a non-fragmenting design.
If fragmentation is likely to be an issue in your plant or process, there are several steps you can take to mitigate the problem:
If you would like to learn more about reducing fragmentation in compliance with regulations, our Design Engineers are ready to help you with a a no-cost and no-obligation consultation or a site survey. During a survey, our engineer will inspect all the rupture disc installation points in your plant or application(s). The resulting report can be used to demonstrate compliance with ASME Section XIII and to identify opportunities for stock consolidation and cost reduction.
Contact us now to request a consultation or site survey.