Case Studies

Problem: As is common in the refining system over time, refractory loss inside flue gas lines allowed heat and abrasion to deteriorate a line wall, causing it to fail.

Solution: Early detection was critical in this case. Routine infrared thermographs aided in detection of problem areas. After identifying problems, prompt repair avoided imminent line failure.

When repairs became necessary, several factors had to be considered before initiating the fix. Internal and external temperatures of the line, product in the line, size of failure, the integrity of the parent material, location of the repair, and the ability to physically make the needed repairs in the given conditions all factored into the process of finding a safe and efficient repair solution.

Repair methods can vary greatly due to the variety of equipment and locations of failures on flue gas lines and vessels, but this instance called for a seal-welded "vent box." This vent box was engineered to address and maintain the structural integrity of the equipment and allowed for a safe installation.

Problem: A waste heat boiler ruptured a tube. In order to repair the unit while it remained on-line, it had to be isolated from the flue gas lines that ran to it.

Solution: Although the flow of flue gas can sometimes be diverted through the stack via a diverter valve, those valves rarely offer a 100 percent seal and will not isolate the boiler.

Instead of shutting the unit down, HRI installed a "blank" between the diverter valve and the boiler for the client. Provisions had not been made for an isolation point on the section of line where the blank was necessary, so HRI used a water-cutting method to carve out space in the line for new flanges, a spacer, and a blank — while the unit remained on-line. Once repairs to the boiler were complete, the blank could be easily removed with no loss of production.