This document specifies the general principles for the ultrasonic testing of industrial products that permit the transmission of ultrasound. The specific conditions of application and use of ultrasonic testing, which depend on the type of product to be tested, are described in documents which can include: — product standards; — specifications; — codes; — contractual documents; — written procedures. This document specifies the minimum applicable requirements, unless otherwise specified in the referencing documents. This document does not specify: — extent of testing and scan plans; — acceptance criteria. This document describes only conventional probes, however, the general principles for ultrasonic testing also apply to ultrasonic testing using array techniques. If array techniques are used, then additional steps or verifications can be needed.