3.6 Evaluation of indications
Outside-surface-breaking indications found by the ultrasonic method having an amplitude less than 20 % of the height established by the notch of the reference standard may be used as-is.
Outside-surface-breaking indications found by the ultrasonic method having an amplitude equal to or greater than 20 % of the height established by the notch of the reference standard shall be set aside for depth prove-up.
All outside-surface breaking indications found by magnetic particle or liquid penetrant inspection shall be set aside for depth prove-up.
Prove-up of an outside-surface『breaking defect shall consist of notching to the bottom of the indication, measuring its depth and comparing the depth to the maximum allowable stock removal defined in Table 16.
The indication’ s depth may be measured by using a mechanical device (for instance, a depth gauge). The depth of removal of material by grinding or other means to facilitate measurement shall not be deeper than outlined in Table 16.
It is not practical to prove-up indications on the inside diameter of tubes.
3.7 Acceptance criteria
Indications with depths less than the maximum allowable stock removal permitted in Table 16 may be salvaged by removing the indication by grinding. The bar or tube shall be accepted only after complete removal of the indication. All grinds shall be blended to approximately restore the round appearance of the bar or tube.
Indications with depths greater than the maximum allowable stock removal from surface shown in Table 16 shall be rejected.
Inside-surface-breaking indications found in tubes by the ultrasonic method having an amplitude equal to or greater than 50 % of the height established by the notch of the reference standard shall be rejected.
4 Internal defects
4.1 General
Each bar or tube shall be inspected for internal defects by the ultrasonic (UT) method.
4.2 Internal longitudinal defects
4.2.1 General
The full length of each standard steel bar of tube shall be inspected with 360° overlapping scans for longitudinal defects, using both angle-beam (shear wave) transducers and straight-beam (compression wave) transducers.
Inspection of non-magnetic bars and tubes shall be limited to the straight-beam (compression wave) method.
Reference standards shall be used to standardize the inspection unit for each size bar or tube inspected.
The straight-beam inspection shall be performed in accordance with a written procedure developed by the manufacturer in accordance with ISO 9303 except as noted below.
a) A sound section of the bar or tube shall be used as the compression-wave reference standard.
b) The reference standard described in 10.3.3 shall be used to establish a reference level for the shear wave inspection.
c) Transducers shall operate within the range of 1 MHz to 3,5 MHz. Transducers operating at less than 1 MHz may be used on non-magnetic materials.
NOTE For the purposes of this provision, ASTMε114, ASTM E 214 and ASTM E 1001 are equivalent to ISO 9303.
4.2.2 Acceptance criteria for internal longitudinal defects
Any indication in the center of the bar that results in the loss of 50 % or more of the reference standard’s back-reflection and that will not be removed by the boring process shall be considered a defect and shall be rejected.
A bar or tube containing an indication in the mid-wall that results in the loss of 40 % or more of the reference standard’s back-reflection shall be rejected, unless the manufacturer establishes that the loss of back reflection is due to large grains, surface condition, or lack of parallelism between the scanning and reflecting surfaces.
Any indication in the mid-wall having an amplitude greater than the 5 % back-reflection amplitude of the reference standard shall be considered a defect, and shall result in rejection of the tube or bar.
4.3 Internal transverse defects
4.3.1 General
Each bar shall be inspected for internal transverse defects. Inspection shall be by one of the following methods:
a) direct-contact straight-beam method with the transducer placed on the end (face) of the bar or tube;
b) direct-contact shear of wave method with the sound beam oriented in the longitudinal axis of the bar so as to perpendicularly intersect suspected discontinuities.
The method used shall be the option of the manufacturer.
It is not necessary to inspect tubes for transverse defects.
4.3.2 Acceptance criteria for internal transverse defects
All internal transverse indications that will not be removed by the boring process shall be rejected.
