ASTM A939/A939M-15(2020)

3.1 This practice shall be used when ultrasonic inspection from the bore surface is required by the order or specification for inspection purposes in which the acceptance of the forging is based on limitations of the number, amplitude, or location of discontinuities or a combination thereof, which leads to ultrasonic indications.

3.2 The acceptance criteria shall be stated clearly as order requirements.

3.3 This practice requires pitch-catch search unit with twin transducers, which depending on the angle, are sensitive only to 2 in. to 3 in. [50 mm to 75 mm] into the metal from the bore surface.

1.1 This practice covers a basic procedure of ultrasonically inspecting cylindrical forgings with bores from the bore surface.

1.2 This practice applies to the manual testing mode. It does not restrict the use of other testing modes, such as mechanized or automated.

1.3 This practice applies to cylindrical forgings having bore sizes equal to or greater than 2.5 in. [64 mm].

1.4 This practice is expressed in inch-pound and SI units; however, the inch-pound units shall apply unless the purchase order or contract specifies the applicable “M” specification designation (SI units). The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system are not necessarily exact equivalents; therefore, to ensure conformance with the standard, each system shall be used independently of the other, and values from the two systems shall not be combined.

1.5 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.

1.6 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.