HVAF Alloy Coatings to Protect Petrochemical Heat Exchangers from H₂S and CO₂ Corrosion
Petrochemical plants operate multiple heat exchangers exposed to corrosion due to the presence of hydrogen sulphide and carbon dioxide containing fumes and moisture in varying temperature conditions. Categorized as pressure vessels, the heat exchangers are usually made of mild carbon steels with low corrosion resistance.
Kermetico HVAF thermal spray equipment and technology provide a way to mitigate H2S, CO2 and other types of corrosion of heat exchangers and piping by depositing dense metal coatings onto internal surfaces.
Thermal Spray Corrosion Resistant Coatings for Heat Exchangers
The application of a Kermetico HVAF corrosion resistant thermal sprayed coating to the interior surfaces of a heat exchanger forms a barrier between the carbon steel and the sour process fluid preventing corrosion of the heat exchanger shell. Unlike a sacrificial thermal spray coating that is designed to corrode preferentially to protect the substrate, a barrier thermal spray coating needs to completely block the fluid’s corrosive constituents from attacking the base metal. The porosity and the density of the applied coating are important considerations for preventing corrosion of the substrate. Kermetico HVAF thermal spraying is an industrial coating process that uses a chemical (flame) heat source to preheat a powder coating material and spray it onto surfaces. Depending on the corrosion activity of the environment and the planned equipment lifecycle, different HVAF coatings could be applied onto a surface, anything from stainless steel to Hastelloy-type.
A Case of a Heat Exchanger Suffering from Sour Gas Corrosion
Mild steel petrochemical equipment treating sour compounds is subject to severe H2S and SO2 corrosion. Refinery owners decided to protect all their new heat exchangers from corrosion with a Kermetico HVAF Hastelloy-type coating. The inner surface of the heat exchanger was robotically HVAF grit blasted with our AK5 gun and the coating was robotically applied with the same gun.
Completion: 2013, shop application.
Application Method: Kermetico HVAF blast and spray technology. The rotation of the vessel was on rollers with a robotic traverse of the gun on an internal beam.
We have sprayed the cover in rotation with the robot.
We have coated the nozzles with a manual traverse fixture using the Kermetico HVAF AK5 system.
Spray Material: Pre-alloyed (gas atomized) Hastelloy-type powder.
HVAF Blasting Process (Grit: Alumina 150 Mesh; Blasting to “White Metal”)
From rusted surface to “ready to spray” in a single pass!
HVAF Spraying Process: Vessel ID
The Kermetico HVAF AK5 System Depositing a Hastelloy-type Coating onto an ID
HVAF Spraying Process: Head and Nozzles
Heat Exchanger Coating Completed
After three years in operation, the heat exchanger coating is intact and remains in service.
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