08:54 Jun-15-1998 Rolf Diederichs Director, Editor, Publisher, Internet, PHP MySQL NDT.net, Germany, Joined Nov 1998 600
POD of Manual vs. Automatic Testing on Railroad Wheels
After ultrasonic testing was applied manually on all wheels of the ICE of the German Bahn a part of totally 60 trains could start again operation. Yesterday all those trains have been called back!
(Background: Yesterday's broken wheels of the same ICE wheel type used at Hamburg's subway may be leaded to this action)
This shows an uncertainty if those previously manually applied ultrasonic tests are sufficient enough. NDT experts know about this matter, probability of detection (POD), and how to calculate it, how to find the appropriate method.
Automated NDT Advantages and Disadvantages, by Godfrey Hands, Vianen, The Netherlands 1.March.1996
This article describes briefly that the probability of detection of manually ultrasonic testing can be 'only' 80% while automated testing reaches 100%.
Who can say more about it.
And sorry for keeping up the unpleasant broken wheel matter. What shall be done with those trains - can they drive with 80% POD?