How do you size a slug catcher for a multiphase pipeline?

Slug catcher sizing accounts for: steady-state liquid inventory, terrain-induced slugs (liquid accumulation in valleys released at ramps), pigging slugs (all liquid ahead of pig), ramp-up slugs (increasing gas rate releases accumulated liquid), and operationally-induced slugs. Volume = sum of all slug sources with appropriate design margin. Transient flow simulation (OLGA) determines slug volumes for various scenarios. Design includes: residence time for gas-liquid separation, level control range, and liquid handling system capacity. Safety factor 1.5-2.0 on calculated volume.