Deposit Type, Metal Compatibility & Controlled Planning for Heat Exchanger and Pipe Cleaning

Do Not Choose Chemicals Without Knowing the Deposit

When the pressure loss increases or the heat transfer approach temperature deteriorates in plate or tube exchangers, the problem may not only be calcium carbonate scale. Calcium sulfate, silica/silicate layer, corrosion-induced iron oxide (rust/magnetite), organic film, process oil and biological sludge have completely different dissolution mechanisms. Before cleaning, the color of the deposit, layer structure, acid/base response and process history should be evaluated together. Wrong chemical selection may not dissolve the target layer and may impose unnecessary chemical and thermal load on the base metal surface or EPDM/NBR gaskets.

Metal Compatibility and Inhibitor Protection

Carbon steel, copper, brass, stainless steel (AISI 304/316), aluminum and galvanized surfaces can coexist in the same cooling or heating circuit. For example, using standard acids containing chloride in stainless steel plate heat exchangers greatly increases the risk of stress corrosion cracking (SCC) and pitting. Elif Çevre Kimya's cooling tower and maintenance chemicals page separately describes acidic descalers with metal-protecting inhibitors and alkaline organic cleaners for scale, iron oxide and organic deposits. Application concentration, temperature and circulation time must be determined on site according to the type of scale deposit and the most sensitive metal in the system.

Isolation, Controlled Circulation and Neutralization

Before application, the heat exchanger line should be isolated from the main circuit with valves, the gas outlet (ventilation) line should be kept safely open and operators should use full personal protective equipment (PPE). pH, dissolved iron/calcium saturation and foaming should be monitored throughout the circulation; At the end of the process, neutralization, rinsing and surface passivation must be completed completely. Without analysis, constant concentration or duration is not guaranteed.

Field Control and Monitoring List

Chemical dosage and system capacity decisions should be determined by analysis and facility conditions; There is no guarantee of fixed dosage or performance.

• Determination of carbonate, iron oxide, silica or organic/oil character from the deposit sample before cleaning
• Verification of heat exchanger plate/pipe material (AISI 316, copper, carbon steel, aluminium) and gasket type
• Periodic measurement of pH, temperature and acid depletion rate in the circulation tank
• After washing, rinsing with plenty of water, neutralization and passivation of the clean metal surface
• Controlled disposal of waste washing solution in accordance with the plant treatment procedure