A tower-internal performance-guarantee test must define measurable criteria, exact operating conditions, stabilization time, instrument accuracy, sampling, balance closure, data reduction, uncertainty, external-equipment boundaries, and retest rules before startup. Commissioning completion is not performance acceptance. Reliable conclusions require synchronized raw data and an agreed stable operating window tied directly to the contractual guarantee.

Tower-internal piping can transfer weight, pressure thrust, thermal force, vibration, slugging, and installation stress into shell nozzles. Reliable design defines the complete load path, separates hydraulic and structural functions where appropriate, coordinates fixed and sliding supports with external piping, controls field alignment, and assigns reaction calculations among the internal, vessel, and piping designers. Flange bolts must never be used to correct unapproved misalignment.

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.