Ultrasonic In-Service Inspection of Fastening Bolt in High-Temperature Thermal Power Plant

Aiming at overcoming the limitations of ultrasonic testing of high temperatures fastening bolt with a heating hole, this paper presents the method of ultrasonic flaw detection of the bolts on their being heated completely or during shut down period without dismantling the tight cap. This method can effectively detect over 1mm deep crack, and thus can overcome problems related with inspection of this type of bolt.