As per Code Case 2235 the thickness of our Calibration block should be +or- 10% of the Actual Job Thickness, but is there any change in this value as the Thickness of the Job increases more then 250 mm. And what is the requirment of Calibration block as per EN473.
Can anyone give me a copy of CC2235 because my PC crashed last week.
as you make reference to ASME Boiler Pressure Vessel Code Case 2235:
Use of Ultrasonic Examination in Lieu of Radiography,
I assume that you want to perform ultrasonic weld testing.
But European Standard EN 473 does not recommend any calibration block, it gives the general requirements for NDT personnel:
Non-destructive testing Qualification and certification of NDT personnel.
The complete set of 3 International Standards for UT of welds is under revision now:
prEN ISO 17640:2008
Non-destructive testing of welds Ultrasonic testing of welded joints;
prEN ISO 23279:2008
Non-destructive testing of welds Ultrasonic testing Characterization of indications in welds;
prEN ISO 11666:2008
Non-destructive testing of welds Ultrasonic testing of welded joints Acceptance levels.
These standards also make reference to the necessary calibration blocks.
Chairman ISO/TC135/SC3 (UT)
Convenor CEN/TC121/SC5/WG2 (UT of welds)
Abbas, is this for piping or vessel weld inspections. For piping, ASME V Article 4, piping Calibration Blocks, T-434 and Fig. T-434 requires that "The basic calibration block shall be a
section of pipe of the same nominal size and schedule."
For materials < 20" diameter T-418.104.22.168. and Fig. T-422.214.171.124. allows, "a single curved basic calibration block may be used for examinations in the range of curvature from 0.9 to 1.5 times the basic calibration block diameter."
For materials > 20" diameter T-434.2 and .3 and Fig T-434.2 thickness ranges are up to 1", > 1" up to 2", > 2" up to 4" and above 4" with block thickness either as per the Table or the actual thickness t, defined by note (h).
I am not aware of a 10% allowance on calibration block thickness - please can you tell me where did you read this?
Further to Abbas' enquiry I would be interested to read whether inspections to either CC 181 or 2235 require separate qualification and calibration blocks. My response was based on the calibration block requirement with the appropriate notches and drilled holes and NOT the qualification block.
I believe the dimensions of the qualification block will be dictated by the need to demonstrate that the maximum allowable flaw size at the far wall (representing a root defect) will exceed the reference level. In order to best represent the coupling and sound propagation conditions of the work-piece the qualification block should be a section of the work piece material, i.e. the same thickness. If a qualification block is destined to cover a range of workpiece thicknesses, then these conditions may vary across the range covered and replication of the test conditions could be lost.