Rupture disc design

A rupture disc may also be used in some cases for proteetion against internal explosion overpressure. However, this is a matter of special design and the appropriate safety group should be consulted. 

A rupture disc device is a non-reclosing pressure relief device actuated by inlet static pressure and designed to function by the bursting of a pressure containing disc. 

The manufacturing design range is a range of pressure within which the marked burst pressure must fail to be acceptable for a particular requirement as agreed upon between the rupture disc manufacturer and the user or his agent. 

Local rapid flashing, rupture disc/relief valve inadvertently open, release to stack Stack height designed to dissipate release 4 ... 

The client insisted on a test. The smoke detectors worked, and the explosive charge operated, but the cutter did not cut the rupture disc. The explosive charge could not develop enough pressure because the volume between it and the rupture disc was too great. The volume had been increased as the result of a change in design installation of a device for discharging the halon manually. 

Many accidents, particularly on batch plants, have been due to runaway reactions, that is, reactions that get out of control. The reaction becomes so rapid that the cooling system cannot prevent a rapid rise in temperature, and/or the relief valve or rupture disc cannot prevent a rapid rise in pressure, and the reactor ruptures. Examples are described in the chapter on human error (Sections 3.2.1 e and 3.2.8), although the incidents were really due to poor design, which left traps into which someone ultimately fell. 

An explosion rupture disc is a special disc (or disk designed to rupture at high rates of pressure rise, such t run-away reactions. It requires special attention from th manufacturer [35]. 

Rupture discs are specially designed to rupture at a specified relief set pressure. They usually consist of a calibrated sheet of metal designed to rupture at a well-specified pressure. They are used alone, in series, or in parallel to spring-loaded relief devices. They can be made from a variety of materials, including exotic corrosion-resistant materials. 

An important problem with rupture discs is the flexing of the metal as process pressures change. Flexing could lead to premature failure at pressures below the set pressure. For this reason some rupture disc systems are designed to operate at pressures well below the set pressure. In addition, vacuum service may cause rupture disc failure if the relief system is not specifically designed for this service. 

In all these examples the problems are eliminated if the rupture disc and system are specified and designed appropriately for the specific operating conditions of the process. 

Two Rupture Discs with Special Valve Which Keeps One Valve Always Directly Connected to Vessel. This Type Design Is Good for Polymerization Reactors Where Periodic Cleaning Is Necessary. 

The reactor system in a pilot plant contains stock tanks that are 24 in in diameter and 36 in high. A relief system must be designed to protect the vessel in the event of fire exposure. The vessel contains a flammable polymer material. What rupture disc diameter is required to relieve the vessel properly Assume a discharge pressure of 10 psig. The molecular weight of the liquid is 162.2, its boiling point is 673°R, the heat of vaporization is 92.4 Btu/lb, and the heat capacity ratio of the vapor is 1.30. 

The process is run in a semi-batch mode, and multiple reactors are used. There are several possible causes for a loss of control such as insufficient heat removal and loss of agitation. Overpressurization leading to the bursting of rupture discs takes place several times per year, indicating both the clear need for containment but also a need to consider design and control improvements. The reference describes the autoclave rupture disc assembly, procedures for replacement of the discs, the cleaning of the containment vessels, and the routine maintenance procedures for the containment vessels. 

Edition of January 1995. The evaluation of relevant mass-flows is according to safety valves. The use of rupture-discs requires some experience from the design engineer concerning positioning and reaction forces. The exhaust of all safety valves and rupture discs should be connected to a common blow-off tube, at a level above the building. 

Particles (or traces thereof) between seat and disc - especially frequent in pump applications 1. Use a harder and different seat/disc combination. 2. Make sure a knife = edged seat arrangement is used. 3. Use easy to retrofit and compatible soft-seat design - preferably O-ring design. 4. Use bellow valves in case large particles are found or use a rupture disc at both valve inlet and outlet. 

Overpressure accidents can not only damage equipment but also cause injury or even death to plant personnel. In order to reduce the potential number of incidents or accidents, it is the job of the process engineer to analyse the process design and to determine the what can go wrong scenarios and either find a way to design out of them or provide protection against catastrophic failure in the event an accident does occur, that is, install an SRV and/or rupture disc. 

Some method of pressure relief is required on all pressure vessels and for other process equipment where increasing pressure might rupture the vessel. Much of the piping used in modern chemical operations also requires overpressure protection. Safety relief valves or rupture discs are employed for pressure relief. In many cases, either a rupture disc or a safety relief valve can be used. Safety relief valves are usually used for process protection and rupture discs are used for vessel protection. The safety relief valve or rupture disc must be designed to operate at a known pressure and prevent the pressure within the system from increasing. Therefore, it is important to consider the flowrate the valve can handle. 

A rupture disc is a simple device that essentially consists of a thin material held in place between two flanges. The disc is usually made of metal, although it may be made of other materials. The choice of material is important because the rupture disc must be designed to close tolerances to operate properly. During emergency venting, the disc ruptures when the pressure level rises to a chosen level. The vessel is then vented and the pressure in the vessel eventually drops... 

Modeling of Chemical Kinetics and Reactor Design Rupture Disc Sizing Methodologies... 

Each trailer is equipped with a dual safety valve and a dual rupture disc system (Figure 7). These are independent systems manually operated by the driver and can be switched to the alternate if the primary system fails. The capacities of the safety valves are designed to handle a fire on the outside of the container with a uniform surface temperature of 1200°F. 

---