The final component-connection between the Anode Assembly and the Carbon Anode is the “Anode Stub”. This is a short piece of round Steel, ranging in diameter from 150 to 200mm – depending on the technology employed at the smelter. They are welded to the legs of the spider.
Most smelters use rounds in the range of 160 to 180mm, but the newer AP designs use 200mm. The Stub(s) are “consumable” items which almost fill symmetrically located holes in the top surface of the anode. To sustain the joint between the Anode Assembly and Anode, the Stubs are “sealed” into the anode with molten Cast Iron.
Stubs can be supplied as finished pieces complete with a machined “weld prep” (champered end) to weld the stub directly to the anode spider leg. Alternatively Bisley can supply “Stub Steel”, in 6M lengths of Round Bar, which are cut and fabricated to final shape by the Smelter customer, or his local subcontractor.
Modern smelters specify LR Grade, (or ULR) steel for the Stub material. The Resistivity gain is from 22-27 micro.ohm.cm. for a normal commercial grade of Round Bar steel, to 10 micro.ohm.cm for ULR Grade steel.