Pig Signallers, Intrusive and Non-Intrusive

When a pipeline pig is introduced into the line through a launcher, it becomes important to track its progress. The most common way of doing this is to place so-called pig-signallers at strategic points along the length of the pipeline. The most commonly used type is the mechanical intrusive signaller type. However, this requires a physical opening in the pipeline or a flanged 2-inch branch connection. Where this is not possible or for other reasons, non-intrusive signallers can be used. These can be strapped to the outside of a pipeline to detect a pig passage through the pipe wall. Detection options in this case are either magnetic or acoustic (ultrasonic).