Rupture discs – an introduction
Why rupture discs
Rupture discs are, next to safety valves, the most commonly used pressure protection devices in industrial plants. They protect vessels and pipelines from deformation and other damage. The main objective is to optimally protect and, at the same time, minimise the downtime of the system.
What is a rupture disc
Rupture discs are safety devices with a defined breaking point, which respond to a specific pressure and are used for pressure relief in the most diverse range of applications. They are used to protect against overpressure or vacuum within a process, for the protection of man, environment and machine. Originally a very simple solution, rupture discs have evolved enormously in response to growing industry requirements such as alternating pressures or higher process temperatures, and the increasing technologisation of processes in recent years. The biggest advantage over electronic, pneumatic, or spring loaded safety systems is the failsafe performance of rupture discs - this makes them the most economical and most important safety device in industrial enterprises. High reliability is important to prevent unnecessary downtime of the system. However, how failsafe a rupture disc is significantly depends on the workmanship and the material used.
Design of rupture discs
Rupture discs for pressure relief are round or square, consist of one or more layers, and are either flat or domed.
Many rupture discs are equipped with breaking points which are created for example, by means of lasers. These can be simple cuts or even special geometries. This part of the rupture discs is known as the rupture element.
Different applications require different types of rupture discs. They are made of metals or plastics, from one or more layers, and they can be domed or flat. Domed rupture discs either have the dome towards the process (reverse-acting rupture disc), or away from the process (forward-acting rupture discs). Within these different varieties, there is a broad range of possible combinations.
For example, plastic film is sandwiched between metal layers for triple section rupture discs, in order to reach even the lowest burst pressures. The materials used range from various stainless steels to higher quality materials such as Inconel, Hastelloy, or Tantalum, and all the way up to coatings or plastic liners such as PTFE or FEP.
Rupture discs are either installed directly between flanges, or inserted into a corresponding rupture disc holder, which is then mounted between flanges. In some cases the rupture disc is already soldered or welded into the holder by the manufacturer. These holders are then fitted with the necessary connections, e.g. thread (NPT, G or customer-specific thread, connection systems (e.g. VCR) or various flanges (ISO-K, KF, ISO-F, CF)).
A large number of rupture discs and other safety devices are installed in industrial plants. A broad range of signalling options are available, to immediately receive information about the triggering (opening) of a rupture disc. The easiest way to achieve this is with a tripping wire which is fixed on the rupture disc, and is connected to the process control system. With the opening of the bursting disc, the wire breaks, the circuit is interrupted and the triggering of the rupture disc is communicated to the process control system. If there are particularly high demands for leak-tightness, non-invasive signalling methods (e.g. magnetic proximity sensor NIMU) are used.
Type classification of rupture discs
Reverse-acting rupture disc
The dome of the rupture disc faces the process and enables very high operating pressures (see also: key technical information on rupture discs) and a very high operating pressure ratio.
Forward-acting rupture discs
The dome of the rupture discs is faced away from the process.
Compact rupture discs
These are usually very small nominal pipe size of reverse-acting or forward-acting rupture discs which are often adhesively bonded or soldered to the housing / holder.
Key Technical figures of rupture discs
Dimensions: The diameter of the rupture discs is specified matching the diameter of pipes or flanges as the nominal pipe size DN (Diamètre nominal) in the European context, or as NPS (Nominal Pipe Size) in other regions.
Burst pressure (also referred to as set pressure): This is the pressure at which the rupture disc opens. It is selected in such a manner, that the rupture disc opens before there is any system damage. The burst pressure is above the prevailing pressure during normal operation (also referred to as working pressure or process pressure) and below the pressure resistance (MAWP) of the respective system.
Example: At an operating pressure (working pressure) of 1 bar and a 2 bar pressure resistance (MAWP) of the system, the burst pressure is at max. 2 bar or lower, depending on the type of rupture disc.
Burst tolerance: Defines the tolerance around the defined burst pressure, which opens the rupture disc. If a rupture disc type has a burst tolerance of +/-10%, and the defined burst pressure is 1 bar, the rupture disc will open between 900 mbar and 1.1 bar.
Depending on the valid or applied rules and regulations the burst tolerance is at +/-10% (e.g. Pressure Equipment Directive 2014/68/EC), or +/-5% (e.g. ASME section VIII, Division 1), or +/-3% for very high burst pressures. Other burst tolerances are possible depending on the requirements of the respective process.
What must be observed when selecting a rupture disc?
Reliable and economical rupture discs are not standardized products, but are always individually tailored to the respective process conditions. Numerous parameters are taken into account for the manufacture of rupture discs, in order to ensure optimal function.
These include, for example:
Contact us and we will gladly provide you with a comprehensive consultation on the rupture discs which are suitable for your individual process, taking into account all relevant parameters - for minimal downtime and maximum safety.
Overview of REMBE® rupture discs
All designs shown here refer to rupture discs to relieve unwanted overpressure and/or vacuum. Rupture discs are also used for explosion safety. These rupture discs, also referred to as explosion vents, are often rectangular and have a much larger footprint. More information about this topic can be found under explosion safety - explosion vents.
Rupture discs from REMBE® - minimum downtime, maximum safety
REMBE® rupture discs are technically sophisticated safety devices, which are individually manufactured and tested for each application. They open at an exactly predefined pressure and relieve it from the system. Our rupture discs can be used as primary or secondary relief devices. In combination with a safety valve they are often an economically attractive option which protects the valve against product contamination or corrosion damages
All REMBE® rupture discs are made in Germany and certified according to PED (2014/68/EU), as well as all common and industry-specific international regulations and standards. These include ASME sec. VIII, Div. 1, KOSHA (South Korea) and TR ZU 012 / 2011, TR ZU 010 / 2011, TR ZU 032 / 2013.