H4-HH7-B rsions can also be made available Applicationspec Helical speed reducers H4

Flender/Flender Gear Units/Helical speed reducers H4

heck of the sound paths necessary for full nspection of the weld joint, the probe shall be moved (half skip and full skip distance) unt il internal and external notches on the test piece are detected (see Fig. 5 of this spec ification). The relevant defect limits the path lengths on the time base. reference sensitivity is obtained by utilising the through drilled test hole in the thickness of the reference block to draw the distance amplitude correction curve relevant to the test probe. Calibration shall be carried out according to the following rocedure : place its internal vertex until the maximum height of echo is displayed on the screen; this echo is adjusted to 8% of full screen height by means of the sensitivi ty adjuster set in dB. Without varying the amplification, the probe placed at full ski distance from the hole is moved to detect the external vertex the hole until the maxim um height of echo is obtained. The straight line connecting the peaks of the two ech oes obtained by the above procedure, represents the 1% reference level, while the one connecting the two points at half height of the same echoes represents "5% re ference level". The two straight lines shall be marked on the screen with en. Calibration shallbe repeated each time tests are re-started at intervals not longer than 3 minutes during ; altered. This calibration is applicable provided that the crystal of the prob is 8 9mm size. Should , vity obtained from the calibration by crystal of different size shall be brought to the value of sensitivity obtained from the calibration by 8 9mm crystal. The sensiti vities of the two different size probes shall be compared through the echoes obta ined on the notch of the test piece with the probe position at half skip of the dist ance. 1.9 Regulation of Amplification duri