The first line of defense against interanl corrosion is the removal of corrosive diluents and water from the gas. As noted above, this purification process must produce gas that meets a pipeline's gas quality standards or the incoming gas is at risk of being refused transport. Liquid and gas sampling is conducted routinely at our larger receipt points to monitor and maintain gas quality. In addition to hydrostatic testing, there are other inspection methods that can be used if internal corrosion is suspected. One method is smart pigging.
Smart pigs are electronic devices that can measure and gather importan data insidce a pipeline.
Smart pigging technology has not developed sufficiently to reveal all possible internal and external problems, but pigs can investigate significant pipeline characteristics such as sizing, wall thickness, internal and external corrosion, and some anomalies. Each smart pig has a different function, so one pig will not look for all problems in a single run, requiring multiple runs with different smart pigs to get a more complete picture of the piepline's intergrity. This method is only possible where the pipeline's physical configuration allows it. Excavation for pipeline observation, also known as bell-holing, is another method used to detec internal corrosion. Another method is the use of coupons, which are weighed strips of metal made of the same material as the pipeline.