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BHP
REACTS QUICKLY TO AN INCREASE IN WELD FAILURES
BHP Iron Ore Railway recently had to deal with a sudden increase in weld failures
which prompted it to undertake swift research and immediate action.
Graeme Offereins, Manager, Track & Signals, BHP Iron Ore gave an interview to
our correspondent.
We operate a 900km heavy-haul network in the Pilbara region of Western Australia.
On the main line between Newman and Port Headland, trains operate with an average
axleload of up to 40 tones and peak axleload of up to 45 tonnes. This year will see 90 mil-
lion tones hauled over the track.
In such an extreme operating environment, it is necessary to understand and elimi-
nate all track faults. Therefore, a recent experience with the sudden failure of alumino-
thermic welds presented us with a problem that needed urgent attention.
Our aim to optimize the ability of the track structure to carry increasing axleloads
meant that we had invested money over a number of years in research and development of
the aluminothermic welding process. As a result, we were able to provide high-quality
welds under extreme loads.
However, between May and November 2000 we were suddenly confronted with 50
broken welds in track, two of which caused derailments. Most of the failures occurred
within a month of installation.
The failures were sudden and could not be detected in advance by ultrasonic inspec-
tion, even on our 10-day testing cycle. The welds were also spread throughout the track
and, interestingly, the web fractures were more prevalent on straight sections than curves.
We immediately hired a rail testing contractor to examine with gamma radiation all
welds since the start of 2000. This enabled us to see the foot area of the weld which can’t
be seen with track-mounted ultrasonic equipment.
Using a root causes analysis approach to the problem, we listed all the factors that
could influence the quality of the weld. Using this list, we investigated the main causes of
failures, and what preventative measures were needed to reduce the risk of continuing fail-
ures.
All welders underwent special training course. A quality audit was carried out on
the manufacture of the raw materials used in the welding.
We intensified the research work being done by Monash University and included
an investigation into the failures and the reasons for the sudden increase in failures.
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