Pigs are designed for optimal cleaning at around 5 m/s. Erratic movement can result from low flow and planing over areas such as welds and over liquids at higher speeds.
In large pipelines with ultra high velocities, operators are reluctant to reduce flows down for pigging, as this results in a reduction of revenue generating delivery. We have designed bypass pigs specifically for these circumstances which can react to changes in speed and automatically slow down or speed up. The Speed Control Pig constantly monitors and records its surrounding environment. At predetermined speeds increased bypass is allowed through the pig to slow its progress and bypass is reduced to increase speed. The extra bypass through can be useful for moving loose deposits ahead of the pig.