Electric power transformers do not operate at 100% efficiency, and generally incorporate some means of cooling in their design. Large transformers are often submerged in oil-filled reservoirs, where the volume of oil provides a noncorrosive heat sink. In addition, it is not uncommon for additional features, such as horizontal cooling fins, to be added to the design to aid in dissipating heat from the reservoir.
Figure CS-38 shows the exterior of a large transformer that has been installed in a rural, somewhat-remote location. The reservoir housing has been constructed by welding 9- and 12-mm (§- and ^-in.) thick, low-carbon steel plates. While the transformer was in use, a service vehicle accidentally backed into the cooling-fin assembly, producing cracks in several of the fillet areas and a resulting loss of oil. Overheating occurred, and a repair is now necessary. Because of the size of the transformer, some form of on-site repair is preferred. It is your job to determine the procedure and make the necessary arrangements.
1. Consider the full spectrum of welding processes and identify candidates that might be appropriate for this task.
2. For each of the candidate processes, identify its primary advantages and limitations.
3. Which of the candidate processes would you recommend? Why?
4. Describe the procedure that you would outline for such a repair. Are there any special concerns or precautions?

Fillet Cooling fins welds FIGURE CS-38