On November 28, 1999, a blockage occurred in the South Teal Unit. The blockage or plug occurred somewhere in the recycle waste line on the second level of South Teal. This line brings crude Teal with excess aluminum to T-103, which feeds back to the reactors. During the night shift, they were able to blow the line from T-105 to the control valve, which left the blockage within about 20 feet of T-103.
On the morning of November 29, 1999, Employee #1, the outside operator, tried to blow out the plug through a detail (bleeder) just above T-103 with 150 pounds of nitrogen. The detail was also plugged.
The system was isolated, and a lockout/tagout permit was obtained. To unplug the detail, Employee #1 had to bolt a packing gland (which had a rod to push the plug through) and clear the plug from the detail. Then he tried the 150-pound nitrogen through the detail again. The nitrogen was able to move through the line back toward the control valve. The nitrogen pressure went around the control valve via a bypass to the slop tank.