The design required the small version robot to enter the pipeline through a 3-inch taphole.
Small VGC provides inspections of live gas mains under no blow conditions via a taphole drilled using standard hot-tap equipment.
It is designed for quick and easy access and permits a visual inspection of up to 200 feet from a single taphole (100 feet in each direction).
After a predetermined amount of time, the cupola is tapped by ramming a steel bar into the taphole.
If the dam is raised to slowly allow even small amounts of blast air to escape through the taphole, the taphole will wear quickly.
Allowed to occur, this can create a real mess in the taphole area.
Once this area is free of slag and only clean refractory is visible, the taphole is ready to repair.
Repair consists of laying a hollow metal taphole pipe in the breast at the right measurement and thoroughly ramming the proper refractory around the pipe.
This hole is located about one-fourth of the way across the bottom from the taphole.
Once operators are certain that no molten material remains in the cupola, the taphole is rammed full of refractory and then the cupola coke is quenched with water through the tuyeres.
If that happens, the tuyere taphole should be rodded to ensure that it is open and the iron dam may need to be lowered.
If iron and slag both are flowing freely at the taphole and into the safety tuyere, the melting operation should stop and the tuyere access opened and rodded.