Abstract: A self-propelled vehicle for use in performing work inside pipes of piping systems, for example, for cleaning or coating the inner surface of the pipe includes at least three traveling assemblies connected to the body of the vehicle by parallel link assemblies. The traveling assemblies are travaeled along the pipe inner surface to be worked on by the operation of a drive unit and transmissions while being pressed against the pipe inner surface by a collapsing assembly. During travel, a liquid can be sprayed onto the pipe inner surface by a nozzle which is rotated.

Abstract: A method of ultrasonic flaw detection of a pipe comprises comparing ultrasonic waves passing through a test piece portion with the arithmetic means of ultrasonic waves passing through portions adjacent each side of the test portion. The comparison is made around the entire periphery of a pipe, for example, an austenic heat resisting cast steel pipe used as a hydrogen manufacturing reformer tube. This method is free from adverse influence of macrostructures unevenly distributed in the peripheral direction of the pipe, and enables a quantitative grasp of flaws in a base material and a weld of the pipe.