Pipeline Pigging Volume, Velocity, and Batch Displacement

A pipeline is a very long cylinder and its volume is larger than intuition suggests, which is the number that sizes the receiver, the tankage, and the displacement batch all at once. Pig velocity follows directly from flow over area, and it matters for more than scheduling. Too slow and a cleaning pig can stall, or its bypass lets debris past; too fast and an inline inspection tool's sensors cannot sample properly and the run has to be repeated at the cost of another mobilisation. Most inline inspection tools have a stated velocity window, and checking that the planned flow puts the tool inside it -- before the tool is in the line -- is exactly what this is for. That check is reported as a verdict computed from the velocity rather than as a number for the reader to compare by eye, and it names which end of the window was missed and the throughput that would fix it, because a velocity a little under a minimum reads as acceptable at a glance and is not. For a batched liquid line the same volume arithmetic sizes the interface: two products in contact mix over a length that grows with the distance travelled, and the contaminated interface volume has to be cut to slop or downgraded, a real cost that scales with the line volume. Barrels convert at 42 gallons of 231 cubic inches, exact by definition. This assumes a constant inside diameter and a full line: it does not model bypass around the pig, the differential pressure needed to drive it, tool wear, or the interface mixing length itself, which depends on the products, the flow regime and the distance. The tool vendor's velocity specification and the operator's pigging procedure govern.

line volume V = (pi/4) d^2 L converted at 42 gallons of 231 cubic inches per barrel; pig velocity = flow / volume per unit length; travel time = length / velocity; and the flow that reaches a target velocity is that relation inverted.

The geometry of a cylinder with the exact petroleum-barrel conversion, and pig velocity as flow over area. The inline inspection tool's velocity window is ENTERED from the vendor's specification. It assumes a constant inside diameter and a full line, and does not model bypass around the pig, the differential pressure driving it, tool wear, or the batch interface mixing length.

One cylinder volume and one exact unit conversion.

Estimate. AHJ and licensed professional govern.

Field names used by the API: id_in, length_mi, flow_bpd, tool_min_fps, tool_max_fps, bbl_per_mile, total_bbl, velocity_mph, velocity_fps, travel_time_h, flow_for_min_bpd

• Constant inside diameter a real line has fittings, bends and diameter changesthe line's own records
• The tool window is entered every tool has its own specificationthe inline inspection vendor
• No bypass model a cleaning pig's bypass changes both velocity and cleaningthe pigging procedure