Ultrasonic testing of hot welds

TLDR: In this article, the design of special probes, the choice of suitable coupling media and the effect of temperature on the response of the flaw detector are discussed, and the possibility of ultrasonic testing at high temperatures is explored.

Abstract: Steel of certain qualities, particularly for use in thick-walled objects, must be pre-heated before welding to 200–300°C. Since standard ultrasonic probes fail to operate properly at temperatures much above 50°C, it is necessary to cool hot test pieces before ultrasonic inspection of weld seams and weld repairs can be undertaken. Thus, if the weld or repair is found to be defective, it must be reheated before further repairs can be made. This process is time consuming and costly and this article explores the possibility of ultrasonic testing at high temperatures. The design of special probes, the choice of suitable coupling media and the effect of temperature on the response of the flaw detector are discussed.