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A: That’s the classic gap — assuming a gas PSV sees liquid behavior. A PSV on the vapor space won’t relieve incompressible liquid expansion when the vessel is blocked in; pressure rises too fast. Fire, valve failure, and flow transients all generate vapor-side pressure the PSV can actually see and relieve.

A: That’s where people overcorrect. Coated carbon steel fails once the coating holidays, and 316L isn’t immune to SSC in this environment. Monel works but blows the budget for no added risk reduction. Duplex hits the NACE limits with margin while keeping fabrication and inspection sane.

A: That’s the trap — treating all ‘flow’ as the same variable. The meter’s fine; the issue is mixed bases. One system is correcting to mass using live density, the other is freezing base conditions. Swirl or scan rate errors don’t land you at a clean, stable 5% offset across operating ranges.

A: That’s the blind spot — SIL math assumes independence. Two transmitters seeing the same foam don’t give you diversity; they give you synchronized bad data. Hardware random failures and power issues are already in the SIL calculation, but common process effects sail right through.

A: That’s where people confuse maximum capacity with controllability. A huge single valve hunts at normal rates, and a ball valve gives you poor resolution. An orifice just moves the problem upstream. Split-range or parallel valves let you control day-to-day while still surviving slugs.

A: That’s the geometry biting you. Raising the nozzle silently raises the hydraulic weir, shrinking the usable control band. Calibration tweaks or density changes won’t fix a physical elevation mismatch, and fail position issues show up as clear safety deviations, not oscillation.

A: That’s the subtle one — insulation changes the time-temperature curve. You might slow heat input, but you can also push the vessel into a longer-duration, high-temperature exposure where strength drops. Vapor rates don’t magically increase, and the other items aren’t fire-sizing assumptions.

A: That’s where surface metrics mislead. Raw counts and self-reported progress lag reality. When each punch is tied to a system and that system gates a milestone, trends break early and honestly, even when the numbers still look ‘fine’.

A: That’s the classic vendor-data blind spot. Internals don’t behave symmetrically across the envelope. At low velocities, vanes don’t shed liquid, so you get re-entrainment. Pressure drop, weight, and corrosion don’t selectively show up only at turndown.