Tower internals can suffer deep localized MIC during hydrotest retention, construction delay, mothballing, or extended shutdown. Prevention requires controlled water quality, deliberate dry or treated-wet preservation, complete drainage or verified drying, representative monitoring, compatible biocide or inhibitor selection, and inspection of stagnant crevices and low points. Nominally draining the tower or testing only the supply water does not demonstrate protection.

Abrasive blasting and shell recoating can erode, contaminate, plug, or immobilize retained tower internals. Protection requires an engineered remove-or-retain decision, robust isolation barriers, controlled abrasive and ventilation, accountable temporary covers, overspray management, thorough hidden-area cleaning, and functional inspection of holes, valves, drains, bonds, and expansion joints. Shell-coating acceptance and internal-equipment acceptance must remain separate hold points.

High-pressure water jets can deform, cut, dislodge, or strip thin tower internals even while removing deposits effectively. Safe cleaning requires deposit characterization, component-specific jet limits, controlled nozzle distance and dwell, verified scaffold and drainage loads, shielding of vulnerable parts, progressive inspection, and post-cleaning dimensional and mechanical checks. Pump pressure alone cannot define cleaning severity, and complete visual cleanliness is not worth hidden structural damage.

Scaffold legs and turnaround equipment impose concentrated, horizontal, and dynamic loads that tower internals may not be designed to carry. Safe temporary work requires an allowable-load map, verified structural bearing points, engineered spreaders, controlled material storage, review of hydroblasting and lifting forces, and inspection before and after use. Never infer load capacity from appearance or worker experience; provide a documented load path to qualified vessel supports.

Protective coatings reduce and irregularly reshape tower-internal holes, slots, mesh openings, sliding clearances, and bolt fits. Reliable design specifies finished dimensions, accounts for maximum coating buildup and stripe coats, prepares edges correctly, controls application and curing, and verifies critical openings after coating. Flat-surface thickness readings alone cannot prove hydraulic suitability; final dimensional inspection and post-coating performance testing are often required.