Recent Developments in Contra-flow Crawler in Pipeline

Pipeline Inspection Gauge (PIG) is a device which is inserted into a pipeline and travels throughout the entire length of pipeline and has been used since over 100 years in the petroleum industries to maintain the condition of pipelines mainly for smoothness of production and transportation of hydrocarbon products. Setbacks of conventional PIG; (1) can only move in the direction of the fluid flow, and therefore, (2) they need to be inserted at a specific point in the pipeline during application. This exercise is costly or even dangerous in some circumstances as it requires intervention of human. In order to overcome such difficulties in pigging, several development works of pipeline contra-flow crawler have been developed and aimed at solving the problem of entering and leaving the pipeline from a single exit. The essential bidirectional capability makes it very valuable to many industries, especially the petroleum industries. The objective of this paper is to review the recent developments of contra-flow crawler which has become a continual interest of PIG developers. The review carried out would serve as an industrial application in a form of a quick reference of recent developments in contra-flow crawler in pipeline, and for related industries.