Vapor crossflow can push liquid-distributor jets away from their intended landing points even when outlet flow rates are equal. The risk increases with long free-fall distances, weak jets, low liquid rates, high local vapor velocity, and structural blockage. Distributor acceptance should therefore evaluate the complete path from outlet to packing—not only the flow through each hole.

Reliable FRP tower internals require a defined laminate schedule, exact resin and reinforcement traceability, controlled lay-up and cure, appropriate cure verification, glass-content and coupon testing, inspection for voids and delamination, sealed edges, qualified joints, and complete repair records. Thickness, appearance, or Barcol hardness alone cannot prove structural strength and corrosion-barrier integrity.

Iron-sulfide deposits on tower internals can oxidize rapidly and self-heat when exposed to air during shutdown. Prevention requires service-history review, controlled inerting, continuous wetting or approved chemical treatment, verified coverage of hidden internal surfaces, temperature and atmosphere monitoring, safe opening sequence, and controlled waste handling. Treated deposits can become reactive again if they dry, and cleanup must not overload or chemically damage the internals.

Fluoropolymers resist many chemicals but still permit molecular permeation. Fluid accumulating behind a bonded or loose lining can create interfacial pressure during heating, cooling, vacuum, or rapid depressurization, causing blistering and delamination. Reliable design requires representative permeation data, suitable lining architecture, prepared substrates, qualified edge and seam details, controlled venting, thermal-movement allowance, and inspection beyond holiday testing.

Plastic tower internals cannot be verified through one metal-style PMI test. Reliable acceptance combines exact resin-grade specification, batch traceability, FTIR, DSC, density, melt-flow or other applicable tests, finished-part sampling, fabrication inspection, and comparison with approved reference material. No single test proves polymer identity, additives, processing quality, reinforcement, and long-term service performance simultaneously.