ISO 10893-9:2011 pdf free download – Non-destructive testing of steel tubes一 Part 9: Automated ultrasonic testing for the detection of laminar imperfections in strip/plate used for the manufacture of welded steel tubes.
7 tquipment calibration and cnecing
7.1 At the start of each test cycle, the equipment shall be calibrated statically either without reference standard in accordance with 7.1 a) or using a reference standard in accordance with 7.1 b).
a) Calibration without reference standard: with the probe assembly positioned on the strip/plate under test, the full amplitude of the first back-wall echo minus 6 dB shall be used to activate the respective trigger/alarm of the equipment.
The test sensitivity may also be established with DAC (distance amplitude correction) curves as supplied by the transducer manufacturer or with DAC curves as prepared by the tube or strip/plate manufacturer using, in both cases, the 6 mm flat-bottomed hole curve.
The manufacturer shall demonstrate that, at the set sensitivity, the equipment will detect, under static conditions, the reference recess as given in 6.1 2 and Figure 1. If this is not the case, the necessary adjustment in sensitivity shall be made prior to the production test run.
b) Calibration using a reference standard: under static conditions, with the transducer or each transducer in turn centrally located over the reference standard, the full signal amplitude of the signal obtained from the reference standard shall be used to activate their respective trigger/alarm of the equipment.
7.2 During production testing of the strip/plate, the relative translational speeds and pulse repetition frequency shall be chosen such that the minimum coverage values and maximum separation values between adjacent scanning tracks given in Table 1 are obtained.
7.3 The calibration of the equipment shall be checked at regular intervals during the production testing of strip/plate.
The frequency of checking the calibration shall be at least every 4 h, but also whenever there is an equipment operation team changeover and at the start and end of the production run.
7.4 The equipment shall be recalibrated if any of the parameters which were used during the initial calibration are changed.
7.5 If, on checking during production testing, the calibration requirements are not satisfied, even after increasing the test sensitivity by up to 3 dB to allow for system drift, all strips/plates tested since the previous equipment check shall be retested after the equipment has been recalibrated.
8 Acceptance
8.1 Any strip/plate producing signals lower than the trigger/alarm level shall be deemed to have passed this test.
8.2 Any strip/plate producing signals equal to or greater than the trigger/alarm level shall be designated suspect or, at the discretion of the manufacturer, may be retested. If, after two consecutive retests, all signals are lower than the trigger/alarm level, the strip/plate shall be deemed to have passed this test; otherwise, the strip/plate shall be designated as suspect.
NOTE If applicable, the evaluation can be based on DAC curves.
8.3 For suspect strips/plates, one or more of the following actions shall be taken, subject to the requirements of the product standard:
a) the suspect area shall be explored by a manual ultrasonic compression wave technique in accordance with Annex A to establish the extent of the laminar imperfections. The product shall be deemed to have passed this test if the size and frequency of the laminar imperfections do not exceed the values given in Tables 2 and 3. If the width, C, of the laminar imperfection exceeds the Cmin that shall be considered (see also the note in Table 3), an area of 500 mm x 500 mm with the indication in the centre shall be explored 100 % to establish the presence of other laminar imperfections exceeding Bmax and to determine if the population density of laminar imperfections > and