By-Pass Pigging - A ‘Simple’ Technology with Significant Business Impact

Bypass pigs are similar to normal pigs but have bypass ports to allow for a certain amount of fluid flow through. The bypass flow can “smooth out” the liquid surge. As for non-bypass pigging, all materials present in the pipeline before pig launch will be “pigged” out during the pig passage and nothing will “leak” backward through the bypass ports. Compared to non-bypass pigging, the use of bypass pigging can significantly reduce the production deferment as a result of pigging, capacity requirements for the slug catcher or separator, and the cost of wax inhibitors and risk of wax maintanence pigging. Bypass pigging has been around for many years but simply not been used enough, particularly its potential in handling the pigging slug and reducing production defermerment.This paper presents a case history of a recent successful application in Malaysia. Application of bypass pigging in the trunkline system of Malaysia LNG (MLNG) resulted in very significant production benefits, at virtually zero cost.