A crane collapse onto an electrical switchyard building causing a complete shut down of an oil refinery plant. The refinery company hired a large well known management company to manage and supervise the lifting of heat exchangers for maintenance, repair and replacement. The management company retained the services of a lifting contractor.
The claim was against the management company for improper management of a heavy crane lift that failed at the refinery. The refinery company's contention was that the management company was negligent that caused the crane collapsed**. The management company's contention was that a sudden storm and wind gust were responsible for the rotation of the load and ultimate failure.
There were eyewitness statements of the event, photographs of the crane and load just before the collapse and statements from the crane operator.
There were two investigating reports made available, the refinery report and the management report. These reports are a culmination of engineering expert's views on the causation of the incident. In the refinery report they cited that the Management Company failed to clear all obstruction from around the 100-ton section that was to be lifted. That report also stated that at the moment the crane began to lift the load, it became caught on a vertical pipe flange. It further stated that the hang up caused the load to rotate about the pipe causing the load to shift off the centerline of the crane boom and ultimately caused its collapse**.
The management report contended that the rotation and the failure were directly attributed to Force Majesture, a strong unexpected windstorm. That report also stated that the load was boomed in several times before it started to rotate.
GenTek represented the management contractor and the lifting subcontractor. A three dimensional computer model was developed using engineering drawings of the refinery and crane equipment. The photographs became extremely important for the process of validating the scale and accuracy of the computer model by superimposing the photographs over the computer model. Viewing the computer model from different viewing positions, such as a top view, was now possible once the model was aligned with the photographs.
Our legal and engineering team members wanted to see the lifting sequence according to the statements of the lifting sub-contractor and other eyewitnesses present at the time of the lift.
During the process of adding the animated portion to the model some very important answers were beginning to unfold. The vertical pipe and flange were also modeled and using that as the pivot point the load was animated to rotate about the pipe flange. What it revealed was that in order for the load to rotate into the position depicted in the photographs, it would have to rotate more than ninety degrees. I noticed that the load could not rotate the full rotation without coming in contact with the boom and preventing the load to make the full rotation angle. This information became evident only through the use of the computer model and was never mentioned in both investigating reports.
Unbeknown to all the participants of both reports, the load that was being lifted would have struck the boom if it began to rotate about the pipe at the time of initial lift. It would have stopped the load from rotating at an angle of 45 degrees or less. Site photographs clearly indicate that the load was rotated in excess of 90 degrees. This discovery that was made using the computer model and then verified by calculations strengthened the Management's position. The evidence showed that only when the load was hanging free that it could have rotated the full rotation angle. Because of this finding it is probable that a sudden gust of wind against the lifted load could have caused the rotation and ultimately the failure of the crane boom.
**it is extremely important that the load always remains on the centerline of the crane boom, and even a slight deviation can cause the crane boom to collapse. In this case the load drifted off centerline and locked the rotation bearing that enables the cabin and boom to rotate. The crane operator could not correct the load due to the locking of the bearing and the load remained in this precarious position for almost forty five minutes before collapsing.
John Genuard has over 40 years of experience in the civil engineering field. Extremely well-versed in computer-aided design applications, he also specializes in the development of CAD training programs which enable the training of associated disciplines in basic and advanced usage of MicroStation and AutoCAD software.
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