Industrial Piping Layout Engineering

A: 150 mm. That's the typical minimum vapor space margin above the normal liquid level for a horizontal separator of this class, and the symptom set hinges on it. Stable indicated level and rising demister DP rule out gross level control issues. Fouled demisters and eroded inlet devices explain DP or efficiency loss, but not why the problem appeared only after a layout revision. A lowered gas outlet nozzle steals disengagement height without touching controls or internals, so carryover climbs while instruments look calm.

A: 610 mm OD drives this. Six large lines at roughly 0.6 m each plus one diameter spacing already lands near 4.2 m. Add edge clearance both sides and a realistic 900–1000 mm walkway and you're near 6 m before utilities. Anything under 4 m collapses spacing rules; anything near 9 m assumes access requirements that don't apply to a single-tier offshore rack.

A: 0.03 bar CO2 equivalent is the trigger. At 55°C with free water, CO2 corrosion rates jump when you create stagnant holdup. H2S at 50 ppmv is below thresholds for SSC in carbon steel under normal stress, and oxygen pitting needs a different exposure pattern. Velocity effects matter at restrictions, but the step change after adding a low point points straight at sweet corrosion.

A: 1.0% per 10°C is the number people miss. A 25°C rise can drive pressures well past MAWP in a fully blocked liquid line long before a high-set PSV reacts. Cracking valves creates uncontrolled flow and risk. Dedicated thermal relief sized for liquid expansion is the safe path offshore where response time is constrained.