Home Health Case Studies in Maintenance and Reliability: A Wealth of Best Practices
Outline of Barrel Production Process
We had two identical production lines for the barrel shells and assembly. First we rolled the sheets into cylindrical shells and welded the seam in a seam-welding machine. We then provided corrugations on the shells to give them stiffness. Next we bent the ends and flanged them in a flanging machine. We punched out and formed the circular top and bottom covers separately, using heavy duty presses. The end covers also had flanges to match those on the shells. In the assembly line, we fitted the end covers on the shells. The next step was to bend the flanges together in a seaming machine. Finally, we tested the barrels in a testing machine. For this, we used air at 1" water pressure and soap solution. The operator filled the barrel with air and brushed on the soap solution on the welds and folded seams. Leaks were unacceptable, and leaking barrels (called leakers) had to be repaired by gas welding.
On a normal shift, we experienced 10-15 leakers, or less than 0.5%. These were often due to sheet thickness variations, machine setting errors, etc. Prompt action could keep the leaker rates quite low. But production workers and supervisors had to be vigilant and quick to react when a set of leakers was detected. Without a clear understanding of the process and the machinery, the ex-Utilities supervisor was unable to manage the production line in his shift. As a result, sometimes there were leak rates as high as 3%. This meant that in a single shift, 150 or more empty barrels had to be stored inside the production area till they were repaired. Extra welders had to be brought in, sometimes at the cost of delaying maintenance work in the refinery. On occasion, there was no moving space left inside the barrel factory.
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