A device used to clean or clear away the inside of a pipeline, particularly those used offshore carrying natural gas and crude oil which are prone to the build-up of deposits such as waxes and hydrates. Pigs are made of rubber or polyurethane and the basic design consists of two plates held apart by a short rod. They can also incorporate various sensing and recording equipment. They are launched into the pipeline and move under the effect of an applied pressure; they emit a squealing sound as their blades scrape along the pipeline and are recovered from a receiving trap, which are loops in the pipeline that can be isolated by shut-off valves. Smart pigs or intelligent pigs are inspection devices used to measure the condition of the pipe including metal loss, restrictions, and pipe deformation.