Seeking advice on burst disc issues with equipment

This post was last edited by Shutong on 2023-1-6 07:13. If the medium discharged by the rupture disc in question is toxic or flammable/explosive, then the experts’ opinion is correct! If the medium is toxic or flammable/explosive, an exhaust duct should be installed at the outlet to lead it to a safe location. If it is not a toxic or flammable/explosive substance, it is recommended that the original poster conduct a self-analysis based on the following standards; the design institute should provide a response through calculations, rather than giving such a simplistic and arbitrary reply that leaves the original poster at a loss. GB 567.2-2012 Safety devices for shrapnel – Part 2: Application, selection and installation 6.1.2 Pipeline layout for shrapnel safety devices

The expert has replied, so there’s no need for me to show off anymore；

We’re not experts, just discussing this with everyone: lol

. . . It’s unclear, but if the two explanations aren’t contradictory, why can only one of them be correct? The basic logic doesn’t add up

What was said on the 2nd floor is correct; it makes sense too that the design institute claims that long pipes affect the discharge process. The experts’ statement that discharge into the atmosphere is not allowed might be because of the toxic or flammable nature of the medium – otherwise, it’s unclear what the basis for this claim is. If it is a toxic substance, it cannot be discharged directly into the atmosphere; it must first be collected through pipelines and treated to remove its toxicity before it can be released into the air. If it is a flammable medium, it cannot be discharged directly into the atmosphere either; a flame arrester must be installed on the discharge pipe to prevent backflow of flames. For details, refer to clauses 6.1.2.7 and 6.1.2.8 of GB567.2-2012 \"Safety devices for burst discs – Part 2: Application, selection and installation\" (see figure below). If the medium is non-toxic and non-flammable, it can be discharged into the atmosphere through a vent pipe; however, the following points should be taken into account: 1. The cross-sectional area of the vent pipe should be larger than the discharge area of the burst disc ； 2. The discharge pipes installed outdoors should have measures to protect them from rain and wind ； 3. If the vent pipe is not a straight pipe, it should be led away from the rupture disc device through an elbow with a large radius ； 4. An exhaust opening should be provided at an appropriate location on the drain pipe ； 5. The center line of the drain pipe should be aligned with the center line of the blast disc ； 6. Shut-off valves should generally not be installed on drain pipes, except in some cases ； For details, refer to GB567.2-2012 \"Safety devices for rupture discs – Part 2: Application, selection and installation\" 6.1.2 (see figure below). 7. The vent pipe should be designed to be vertical as much as possible. For details, refer to Appendix B of GB150.1-2011, \"Pressure Vessels – Overpressure Relief Devices\", section B10.1 (see figure below). What the design institute said regarding the impact of long pipelines on relief function is correct. This is because the calculation of the discharge capacity of rupture discs is based on Appendix C of GB567.2-2012 \"Rupture disc safety devices – Part 2: Application, selection and installation\", which deals with the calculation of rupture disc discharge capacity, or on clause 5.12 of API520-2020 Part 1 \"Sizing, Selection, and Installation of Pressure-relieving Devices – PART 1 Sizing and Selection\". Both standards state that the calculated values are applicable only when the length of the pipeline through which the rupture disc discharges fluid is no more than 5 times the diameter of the pipe. For details, refer to GB567.2-2012 \"Safety devices for rupture discs – Part 2: Application, selection and installation\" section 5.5.2 and API520-2020 Part 1 section 5.12.1.1 (see figure below). Therefore, in the case of long pipelines with a length greater than 5 times the pipe diameter, the discharge rate will be affected by the higher fluid resistance associated with such long pipes; it is necessary to take into account the fluid resistance of all components of the actual equipment in order to carry out a comprehensive calculation.

Let’s explore further: What is the purpose of a flame arrester in the discharge pipe downstream of the combustible medium rupture disc? Under normal conditions, the burst disc can serve to provide isolation ； In the event of an accident, the rupture disc may burst, either damaging the flame arrester or interfering with the release of the bursting pressure. It’s unclear what the purpose of such a regulation is.

A flame arrester should be installed on the discharge pipe downstream of the rupture disc for flammable media. In fact, many flammable media contain solid substances; for example, in the case of rupture discs used in polymerization reactors, the monomer is a flammable medium while the polymer is in powder or slurry form, and installing a flame arrester in such situations could be more dangerous. No flame arrester is also designed on the actual unit; instead, fire-extinguishing nitrogen is provided in the discharge pipeline or within the polymerization reactor.