Nondestructive testing methods are increasingly in use. With these methods it is possible to obtain the desired information about the system, without altering or damaging it in any way. This paper examines the possibilities of applying these methods in the quantification of losses incurred by leaking of compressed air from the system in the terms of increasing energy efficiency of the system. The emphasis is on the application of ultrasound detector and IR (infrared) thermographic camera. The potentials and limitations of these technologies are analyzed for leakage quantification on a steel pipe in compressed air systems, as well as the reliability and accuracy of the results thus obtained.