Abstract: A pipeline pig inspection device having a plurality of pressure chambers for detecting pipeline leaks and eliminating erroneous indications of leaks caused by obstructions within the pipeline, significant changes in pipeline diameter, and minor fluid flows through the pig which are not caused by leaks.

Abstract: An ultrasonic inspection method and apparatus for inspecting test objects such as pipeline girth welds are disclosed. Ultrasonic transducers are carried by a track circumferentially mounted around the pipeline. The transducers are mounted in a hollow, open-ended housing and a flexible seal fixed to the housing retains coupling liquid between the transducers and the pipeline to permit the propogation of waves between the transducers and the weld. An adjustable pressure regulating device maintains substantially constant liquid pressure within the housing in order to minimize the loss of coupling liquid and yet insure adequate coupling between the transducers and the weld.