Pig launcher & receiver · complete cycle
Revised classroom model · two-sided pressure and a separate main-line bypass.
Valve colors: green = open, red = closed. *PSV is identification only. Assisted execution uses Do indicated action. Guided practice requires selecting the indicated control; unrelated actions are rejected. Free operation has no prescribed guide sequence. Both are classroom modes, not equipment operating procedures.
Review findings, model limits and sources
Revised from the earlier teaching sketch: K (upstream kicker), E (combined line and pig equalizing connection), T (full-bore trap isolation) and M (main-line bypass) now have distinct roles. The pressure ahead of a pig is separate from the pressure behind it. Once the pig clears the trap signaller, normal bypass flow can be restored while the pig continues down the line. Loading seats the nose near the reducer. Paired vents and drains represent access to both sides, and the closure interlock also checks liquid inventory and isolation. Recovery is drawn as a closed system; its engineering is not modeled.
Illustrative hydraulic model: a downstream node joins main-valve conductance 5M with outlet conductance 2, and also admits trap flow when K and T connect a clear barrel. Conductances are dimensionless teaching choices. E is a combined symbol for balance connections rather than a complete detailed valve manifold. The pig moves out of the trap only above an assumed breakaway difference of 2.5 bar; speed and travel time are uncalibrated. Barrel pressures and liquid inventory use first-order relaxation. Gauge scales are 0–20 bar (0–290 psi). No compressible transients, seal leakage, actual valve Cv, trapped pockets, debris blockage, gas testing or purging are modeled. A zero model reading never establishes real isolation. Three modes are available. Assisted execution verifies model values and marks the next target; its Do indicated action button operates one indicated control. Wait steps advance when their model condition is satisfied. Free mode allows manual loading and valve operation; switching modes preserves the model. Reset restarts both model and guide. These checks do not represent independent field verification. Receiver RT, RO, RE and main bypass RM form a separate teaching circuit with two receiver pressure zones, paired vents / drains, inventory and a closure interlock. Pressure relaxation and routing remain schematic; the full pipeline is displayed as a folded schematic for layout; corner turns indicate diagram routing, not actual bend geometry. Detailed 3D pig guidance, PSV action and real operating verification are omitted.
Sources: HSE HSG253 · pig-trap isolation, pressure on both sides, vents / drains and closure interlocks; Drinkwater Products · high-level launcher flow routing. Real arrangements require their own approved procedure.