Influence of Moulding Pressure on the Burst Pressure of Reverse-Acting Rupture Discs

Rupture discs, also called bursting discs, are widely used in pressure vessels, pressure equipment, and pressure piping in process industries, such as nuclear power, fire protection, and petrochemical industries. To explore the relationship between the burst pressure of reverse-acting rupture discs and their production, two common manufacturing methods, air pressure moulding and hydraulic moulding, were compared in this study. Reverse-acting rupture discs that complied with the form recommended by API 520-2014 were prepared with four release diameters, and burst pressure tests were carried out. These results showed an obvious negative correlation between the forming pressure of rupture discs and their actual burst pressure for all experimental samples. Further study showed that the main reason for this correlation was a reduction in thickness at the top of the rupture disc caused by large plastic deformation during compression moulding. To explore the relationship between the thickness reduction effect and moulding method, this study defined the “relative ratio of thickness reduction” and concluded that the effect of decreasing the thickness of the rupture disc was more obvious for rupture disc substrates with less flexural rigidity. The above conclusions have important significance for guiding the control of the burst pressure of rupture discs.

Equipment for Damping Hydraulic Shocks in Pressure Hydrotransport Facilities

Newly developed equipment for damping hydraulic shocks in pressure hydrotransport facilities is reviewed in this article. This equipment includes a discharge, safety diaphragm, as well as a flexible diaphragm, which is connected to the main pipeline at both different ends of the backpressure valve. A rupture disc is attached to it from below and load is attached from above by means of a rod, so that it can efficiently act during movement of hydraulic fluid in the central main pipeline, i.e. when the flow to be transported contains abrasive contaminant of solid material. The load represents a piston, which is rigidly connected to the flexible diaphragm and the rupture disc and creates an airproof space filled with viscous fluid. At the same time, the lower space is isolated from the main pipeline by a flexible separating element before the backpressure valve and the upper space is also isolated by a flexible separating element located after the back pressure valve.

Finite Element Analysis on the Temperature- Dependent Burst Behavior of Domed 316L Austenitic Stainless Steel Rupture Disc

As a safety device, a rupture disc instantly bursts as a nonreclosing pressure relief component to minimize the explosion risk once the internal pressure of vessels or pipes exceeds a critical level. In this study, the influence of temperature on the ultimate burst pressure of domed rupture discs made of 316L austenitic stainless steel was experimentally investigated and assessed with finite element analysis. Experimental results showed that the ultimate burst pressure gradually reduced from 6.88 MPa to 5.24 MPa with increasing temperature from 300 K to 573 K, which are consistent with the predicted instability pressures acquired by nonlinear buckling analysis using ABAQUS software. Additionally, it was found that a gradual transition from opening ductile mode to cleavage mode happened with increasing temperature due to more cross slips occurring under serious plastic deformation. The equivalent stress, equivalent strain and strain hardening rates acquired by static analysis were effective at rationalizing the temperature-dependent fracture behavior of the domed rupture discs.

Hybrid Rocket Underwater Propulsion: A Preliminary Assessment

This paper presents an attempt to use the hybrid rocket for marine applications with a 500 N class hybrid motor. A 5-port high density polyethylene (HDPE) fuel grain was used as a test-bed for the preliminary assessment of the underwater boosting device. A rupture disc preset to burst at a given pressure was attached to the nozzle exit to prevent water intrusion where a careful hot-firing sequence was unconditionally required to avoid the wet environment within the chamber. The average thrust level around 450 N was delivered by both a ground test and an underwater test using a water-proof load cell. However, it was found that instantaneous underwater thrusts were prone to vibration, which was due in part to the wake structure downstream of the nozzle exit. Distinctive ignition curves depending on the rupture disc bursting pressure and oxidizer mass flow rate were also investigated. To assess the soft-start capability of the hybrid motor, the minimum power thrust, viewed as the idle test case, was evaluated by modulating the flow controlling valve. It was found that an optimum valve angle, delivering 16.3% of the full throttle test case, sustained the minimum thrust level. This preliminary study suggests that the throttable hybrid propulsion system can be a justifiable candidate for a short-duration, high-speed marine boosting system as an alternative to the solid underwater propulsion system.

Analysis on Bursting of Rupture Disc Made by Inconel 600 Alloy

One conventional domed slotted rupture disc, which was fabricated with Inconel 600 alloy, was used in reaction kettle. It was burst after only 2000 times of operational circles. The burst causes were investigated. Morphologies of the fracture were observed by scanning electron microscope and the relatively chemical compositions were analyzed by energy dispersive spectrometer. Meanwhile, metallographic microstructures were also observed and analyzed for the material of the failure of the rupture disc. The results show that the bursting of the rupture disc was caused by fatigue fracture.

3D CFD Arc Fault Simulation in Gas-Insulated Switchgears

Arc fault processes can lead to strong damages in gas-insulated switchgears and have to be considered in the development process. In order to reduce test costs, the development of overpressure protection systems can be supported by CFD arc fault simulations. The paper deals with the modelling and simulation of arc fault processes in gas--insulated switchgears. The developed simulation tool takes into account a three-dimensional arc model and the opening of a rupture disc during the arc fault process. The influence of different insulating media as e.g. SF₆, Air and CO₂ on the arc fault process has been investigated. The simulation model has been validated by measured signals for pressure build-up and arc voltage.