Abstract: Methods and one apparatus are disclosed for inspecting or working on the internal wall surface of a large drum, as a five story high coke drum for use in a delayed coking unit for restoring petroleum fractions. The apparatus or assembly comprises a triangular spider hanging bracket hoisted up to and connected to one end of a crosshead secured across the top of an opening in the top of the drum, and an inspector's or workman's cage having a hoist hooked to one end of the triangular bracket for traversing the full height of one sector of the drum internal wall before the cage is lowered to a temporary deck, the crosshead rotated through a predetermined angle on the drum top, and the cage raised again for covering another sector of the internal wall surface. This assembly forms a fast, thorough, safe, economical, and efficient system for inspecting and/or working on the internal wall surface of a large drum.