Chemical Process Safety: Fundamentals and Best Practices

A: This sequence prevents seal damage and dry running before any energy is applied. B exposes rotating parts and checks flush too late. C introduces deadhead and thermal risk on start. D creates a no-flow condition that defeats the seal design.

A: Correcting the P&ID forces alignment with the rated relieving conditions. B assumes procurement intent without evidence. C ignores backpressure effects on capacity. D confuses header sizing with valve inlet hydraulics.

A: Nitrogen blanketing controls composition and pressure, not structural resistance to external pressure. A is limited while inerting is intact. B is directly mitigated by inert gas presence. C is reduced by excluding oxygen.

A: Loss of NPSH explains pressure fluctuation and low actual flow with the pump energized. B would stabilize pressure at a lower value. C reduces flow smoothly without pressure spikes. D creates false indication but not hydraulic instability.