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ASTM A388-2019 pdf free download

ASTM A388-2019 pdf free download.Standard Practice for Ultrasonic Examination of Steel Forgings
1. Scope
1.1 This practice 2 covers the examination procedures for the contact, pulse-echo ultrasonic examination of steel forgings by the straight and angle-beam techniques. The straight beam techniques include utilization ofthe DGS (Distance Gain-Size) method. See Appendix X3. 1.2 This practice is to be used whenever the inquiry, contract, order, or specification states that forgings are to be subject to ultrasonic examination in accordance with Practice A388/A388M. 1.3 Supplementary requirements of an optional nature are provided for use at the option of the purchaser. The supple- mentary requirements shall apply only when specified indi- vidually by the purchaser in the purchase order or contract. 1.4 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard. 1.5 This specification and the applicable material specifica- tions are expressed in both inch-pound units and SI units. However, unless the order specifies the applicable “M” speci- fication designation [SI units], the material shall be furnished to inch-pound units. 1.6 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 appro- priate safety, health, and environmental practices and deter- mine the applicability ofregulatory limitations prior to use. 1.7 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
6. Apparatus
6.1 Electronic Apparatus—An ultrasonic, pulsed, reflection type of instrument shall be used for this examination. The system shall have a minimum capability for examining at frequencies from 1 to 5 MHz. On examining austenitic stainless forgings the system shall have the capabilities for examining at frequencies down to 0.4 MHz. 6.1.1 Apparatus Qualification and Calibration—Basic qualification of the ultrasonic test instrument shall be per- formed at intervals not to exceed 12 months or whenever maintenance is performed that affects the equipment function. The date ofthe last calibration and the date ofthe next required calibration shall be displayed on the test equipment. 6.1.2 The ultrasonic instrument shall provide linear presen- tation (within 5 %) for at least 75 % of the screen height (sweep line to top of screen). The 5 % linearity referred to is descriptive of the screen presentation of amplitude. Instrument linearity shall be verified in accordance with the intent of Practice E317. Any set of blocks processed in accordance with Practice E317 or E428 may be used to establish the specified 65 % instrument linearity. 6.1.3 The electronic apparatus shall contain an attenuator (accurate over its useful range to 610 % (+1 dB) of the amplitude ratio) which will allow measurement of indications beyond the linear range of the instrument. 6.2 Search Units, having a transducer with a maximum active area of 1 in. 2 [650 mm 2 ] with 1 ⁄ 2 in. [13 mm] minimum to 1 1 ⁄ 8 in. [30 mm] maximum dimensions shall be used for straight-beam scanning (see 9.2); and search units having a transducer with 1 ⁄ 2 in. [13 mm] minimum to 1 in. [25 mm] maximum dimensions shall be used for angle-beam scanning (see 9.3).6.2.1 Transducers shall be utilized at their rated frequencies. 6.2.2 Other transducers may be used for evaluating and pinpointing indications. 6.3 Couplants, having good wetting characteristics such as SAE No. 20 or No. 30 motor oil, glycerin, pine oil, or water shall be used. Couplants may not be comparable to one another and the same couplant shall be used for calibration and examination. 6.4 Reference Blocks, containing flat-bottom holes may be used for calibration of equipment in accordance with 6.1.2 and may be used to establish recording levels for straight-beam examination when so specified by the order or contract. 6.5 DGS Scales, matched to the ultrasonic test unit and transducer to be utilized, may be used to establish recording levels for straight or angle beam examination, when so specified by the order or contract. The DGS scale range must be selected to include the full thickness cross-section of the forging to be examined. An example ofa DGS overlay is found in Appendix X3. 6.5.1 As an alternative to using DGS overlays, an ultrasonic instrument having DGS software, integral decibel gain or attenuator controls in combination with a specifically paired transducer and DGS diagram may be used to evaluate ultra- sonic indications.

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