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Nondestructive testing of railroad wheels at the German Bahn AG

Posted by: Rolf Diederichs , E-mail: rd@ndt.net, on June 06, 1998 at 20:46:23:

Dear Forum participant

In sad coincidence with this month's railway testing issue, Germany just
last week suffered its worst railway accident in more than half a century.
It is very strange that I (Rolf Diederichs) came back from the ECNDT '98
conference Copenhagen via the same route and on the same train, with topical
railway material in my suitcase, only 5 days before the Eschede tragedy.

The accident occurred on June 3 - just as we were putting the final
touches on this month's issue.
We went ahead and released the new issue, with a few additions pertinent to
the accident, although it is not our intention to focus on catastrophic news
(That is fully covered on the CNN webpage).

We'd rather not get into speculations (with the clarity of hindsight)
on what may have been the exact reason for the derailment, but we would like
to see some dialogue regarding the technical background, particularly now that
it has come to light that a broken wheel which was tested ultrasonically has
been implicated. Let us first focus on the following two articles:

1. The ECNDT '98 presentation of
E. Schneider and R. Herzer - Ultrasonic Evaluation of Stresses in the Rims
of Railroad Wheels. You can also hear it in RealAudio.
http://www.ndt.net/article/ecndt98/rail/306/306.htm

2. Archive 1997 No. 6 - June:
Nondestructive testing of railroad wheels at the German Bahn AG
H. Hintze, Deutsche Bahn AG, Kirchmöser (English summary by Rolf Diederichs)
New: The complete German Version: Zerstörungsfreie Überwachung an Radsätzen
der Deutschen Bahn AG. We'll have an English translation of the full version soon.
This article asserts that the applied ultrasonic testing method does not
effectively recognize all possible defects of the wheel. For that reason a task
optimized the technique which showed first good results and plans for the
necessary modifications are underway for a long term investigation at the service
station in Hamburg. Our question mark: Are those investigations completed and
modifications applied??
http://www.ndt.net/article/report/df97/hintze/hintze.htm

It seems that there is a great degree of uncertainty regarding applied
techniques for ICE wheels - Not that the technology is not available - it is!
However, in-service inspection budget issues can compromise safety.
Wheels must be tested economically without disassembling, but how can the
dual needs of safety and economy be met?
More reliable Ultrasonic techniques are used in manufacturing and refurbishing
shops than in-service inspection.

Mr. Hintze Deutsche Bahn AG, in his article:
'The experience of two units (since 1992 Hamburg and 1994 in Munich) showed
that ultrasonic testing with this configuration could not be used.
After a relatively short operation time the wheel material characteristics
changed by hardening in such a way that sound was already absorbed and no
evaluation could be performed by future inspection. For that reason a task force
together with the FhG IzfP optimized the technique ....'

This was stated at the German-French Workshop (DGZfP/Cofrend)
in Aachen in April '97. There were plans to investigate the optimization in Hamburg.
But what happened?
Was it successful?
Was it applied to Munich as well?

Who knows more about this subject?
We will be looking into this in the next few days.

We hope you will all join us in discussing the details of the wheel testing
issue as well as related topics such as 'Risk based NDT management' and
Probability of detection.

Personally, it is troubling to me that as usual, we see economic issues
take precedence over safety.

Rolf

Follow Ups:

  • Re: Nondestructive testing of railroad wheels at the German Bahn AG - H. Wuestenberg, BAM - Berlin 21:43:48 6/07/98 (7)

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