Retrofit of Damaged Corner Risers by Means of Bolted Connections

Abstract

Unlike pot-to-pot cathode busbars, often protected by the potroom working floor (or gratings), risers are usually exposed to accidental collisions with pot tending machine tools, anode assemblies, crucibles and even heavy vehicles. The tap end corner risers of several pots located immediately after the passageways of the Baie-Comeau Smelter’s Potline D had been damaged throughout the years, which led to the mechanical failure of a considerable amount of the welded plates connecting said risers to the passageway liaison conductors. The retrofit of damaged pot-to-pot conductors is traditionally based on welding techniques, often requiring bypass bridges or potline shutdowns. In the fall of 2015, an integrated Alcoa-Hatch multidisciplinary team succeeded to safely replace one of these risers, without production downtime or auxiliary conductors, by resorting to bolted connections in lieu of standard welded joints. This unique piece of equipment has been operating consistently within target for about 10 months.