ASTM-A435/A435M:17 pdf free download – Standard Specification for Straight-Beam Ultrasonic Examination of Steel Plates.
53 The surface of plates inspected by this method may be expected to contain a residue of oil or rust or bodi. Any specilied idcniihcation which is removed when grinding to achieve proper surface smoothness shall be restored.
6. Procedure
6.1 Ultrasonic examination shall be made on either major surface of the plate. Acceptance of defect. in close proximity may require inspection from the second major surface. Plates ordered in the quenched and tempered condition shall be tested following heat treatment.
6.2 A nominal test frequency of 2¼ MHz is recommended. Thickness, grain size, or nucrostructure of the material and nature of the equipment or method may require a higher or lower test frequency. However, frequencies less than I MHz may he used only on agreement with the purchaser, A clear, easily interpreted A-scan should he produced during the examination.
6.3 Conduct the examination with a test frequency and instrument adjustment that will produce a minimum 50 to a maximum 75 % of full scale reference back reflection from the opposite side of a sound area of the plate.
6.4 Scanning shall be continuous along perpendicular grid lines on nominal 9-in. (225-mml centers. or at the manufacturer’s option, shall be continuous along parallel paths. transserse to the major plate axis, on nominal 4-in. I lOO-mml centers, or shall be continuous along parallel paths parallel to the major plate axis, on 3-in. 175-mml or smaller centers. A suitahlc couplant such as water, soluble oil, or glycerin, shall he used.
6.5 Scanning lines shall be measured from the center or one corner of the plate. An additional path shall he scanned within 2 in. (50 mml of all edges of the plate on the scanning surface.
66 Where grid scanning is performed and complete loss of back reflection accompanied by continuous indications is detected along a given grid line, the entire surface area of the squares adjacent to this indication shall be scanned. Where parallel path scanning is performed and complete løss of back reflection accompanied by continUous indications is detected. the entire surface area of a 9 by 9-in, 1225 by 225-mini square centered on this indication shall be scanned. The true bound• aries where this condition CSts*s shall be established in either method by the following technique: Move the transducer away from thc center of the discontinuity until the heights of the hack reflection and discontinuity indications arc equal. Mark the plate at a point equivalent in the center ol’ the transducer. Repeat the operation to establish the boundary.
7. Acceptance Standards
7.1 Any discontinuity indication causing a total loss of hack reflection which cannot he contained within a circle, the diameter of which is 3 in. 175 mml or one half of the plate thickness. sshichcser is greater. Is unaccqsahle.
7.2 The manufactLlrer reserves the right to discuss rejectable ultrasonically tested plates with the purchaser with the object of possible repair of the ultrasonically indicated defect before rejection of the plate.
7.3 The purchaser’s representative may witness the test,
8. Marking
X. I Plates accepted in accordance with this specification shall be identified by stamping or stenciling IT 435 adjacent to marking required by the maicnal spccitication.
9. Key words
9.l nondestnictivc testing; pressure containing parts’. pressure vcsscl steels; steel plate for pressure vessel applications; steel plates; straight-beam; ultrasonic esaminations.