【国外标准】 Standard Practice for Ultrasonic Pulse-Echo Straight-Beam Contact Testing

5.1 This practice employs the use of normal-incident, or straight beam, longitudinal wave ultrasound for the detection and evaluation of discontinuities in materials requiring volumetric examination.5.2 Although not all requirements of this practice can be applied universally to all inspection situations and materials, it does provide the basis for establishing contractual criteria between suppliers and purchasers of materials for performing contact longitudinal wave pulse-echo examination and may be used as a guide for writing detailed procedures for particular applications.5.3 Types of information that may be obtained from the pulsed-echo straight-beam practice are as follows:5.3.1 Apparent discontinuity size (see Note 1) by comparison of the signal amplitudes from the test piece to the amplitudes obtained from a reference standard.5.3.2 Depth location of discontinuities by calibrating the horizontal scale of the A-scan display.5.3.3 Material properties as indicated by the relative sound attenuation or velocity changes of compared items.5.3.4 The extent of bond and unbond (or fusion and lack of fusion) between two ultrasonic conducting materials if geometry and materials permit.NOTE 1: The term “apparent” is emphasized since true size depends on orientation, composition, and geometry of the discontinuity and equipment limitations.1.1 This practice2 covers ultrasonic examination of materials using the conventional pulse-echo method using straight-beam longitudinal waves introduced by direct contact of the search unit with the material being examined.1.2 This practice shall be applicable to development of an examination procedure agreed upon by the users of the document.1.3 Units—The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.