SAFETY IN THE PLANT


ignition and an explosion (gas, vapour, mist or dust) may arise and that steps must be taken to mitigate the effects, thereby safeguarding personnel and (as far as practicable) maintaining the integrity of the plant. Te options available to achieve this are dependent on the plant vessels/layout and the characteristics of the materials. Tere is a choice of two designs.


CONTAINMENT An explosion pressure resistant design (EPRD) does not allow for any deformation of the vessel whereas an explosion pressure shock resistant design (EPSRD) does – i.e. deformation is acceptable, but not total failure. Explosion pressure relief is perhaps the most common option but essentially there is a ‘loss of containment’, meaning that process material and/or fumes will be emitted from the protected vessel during the explosion. Conversely, explosion suppression and total explosion pressure containment systems do not give rise to a release of process material. Explosion venting is a protective


measure preventing unacceptable high explosion pressure build-up inside vessels/enclosures. Normally explosion venting is applied such that the maximum reduced explosion pressure (Pred, max) does not exceed the known design pressure of the vessel; the lower the vent opening pressure (Pstat) and the larger the vent area, the lower the reduced explosion pressure.


54 www.engineerlive.com


SPROTECTION W


TRATEGY


When it comes to explosion protection measures, a holistic approach is critical, explains Declan Barry


hen discussing explosion protection for process plants, the ‘protection’ concept is based on the assumption that


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