Plant & design
Process Safety
5 self-contained study topics — notes, diagrams, formulas, and worked examples for exams and GATE.
Topics
- Hazard IdentificationHazard identification finds what can go wrong before quantifying it; risk combines the probability and consequence of each hazard, and the ALARP principle guides how far risk must be reduced through inherently safer design where possible.
- Relief Valve SizingRelief-valve sizing first determines the worst-case relief load (from fire, blocked outlet, or runaway reaction) and then computes the orifice area from the API 520 equation, ensuring the set pressure does not exceed the vessel’s MAWP.
- Fire and Explosion BasicsA fuel–air mixture only burns between its lower and upper flammability limits; fire and explosion analysis works with these limits, flash point, autoignition temperature and energy-release estimates like TNT equivalence.
- HAZOP and Risk AssessmentHAZOP systematically applies guide words to process parameters at each node to generate deviations, causes, consequences and safeguards; layered methods like FMEA (RPN) and LOPA then rank and quantify the residual risk.
- Safety Instrumented SystemsA safety-instrumented system reduces risk through automatic protective functions whose reliability is graded by Safety Integrity Level; SIL is defined by the probability of failure on demand, with each level giving a decade of additional risk reduction.