Abstract: The test head includes its own calibration device in form of a wire or a bore in front of the transducing surface so that a distinguishable calibration echo is always available.

Abstract: A tubular sleeve with reflector body, water ingress and venting openings is used to produce specific echoes of a test signal launched by an inserted transducer. Amplitude and transit times of the element serve as a transferable standard.

Abstract: A plurality of water tanks hold a plurality of ultrasonic transducers, each providing a different angle of incidence for ultrasonic radiation for a tube or pipe passing through the tank. Water of a specific temperature is fed to the particular tank being used and in conjunction with a particularly oriented transducer, a particular test angle of refraction is established. Through a particular range of different transducer orientations in conjunction with a temperature range from about 5.degree. to 40.degree. C., a rather wide range of possible refraction angles can be established.

Abstract: An ultrasonic transducer is held in a tubular holder which in turn is axially placed in a mount. A frame depends from a cover of a gimbal mounted container for coupler fluid and the mount is clamped to the frame at an adjustable angle so that the transducer axis always intersects the same point. Ball rollers on the cover position the container in relation to a pipe to be tested so that said point is located on the pipe's surface. The transducer holder has a shoulder onto which one may seat a calibration standard.

Abstract: The entrance angle of an ultrasonic beam into a test object results from refraction at the interface thereof with water. The physical orientation of the transducer directing a beam towards the object is maintained, but the refraction angle is varied through controlled adjustment of the water temperature.