Resistive internal coatings

prolongs process plant life

  • Resistive internal coatings
    Resistive internal coatings

Problems of corrosion, erosion, fouling and wear are common in pipework, pumps, valves and other hollow process vessels. Conventional metal coatings are often ineffective and difficult to apply consistently, but a new process, InnerArmor, overcomes these problems. Available from Wallwork Group company, Tecvac, it uses plasma enhanced chemical vapour deposition (PECVD) to apply even, pin-hole free, thin films of highly resistive diamond like carbon (DLC), titanium carbide or other resilient coatings.

Applications for the new process include pipework and plant in oil and gas exploration and production, downstream petrochemical processing, in chemical plants, water industries and other process plants. Providing an effective barrier on mild steel and other common metals, InnerArmor eliminates the need to use costly exotic metals or alloys. Typical coatings vary from 30 to 80 microns. They can be optimised for hardness, wear and erosion resistance or to tolerate acids, salts, hydrogen sulphide or fluids with abrasive solids such as sand and grit.

Thin films of different materials may be deposited in multiple layers to optimise adhesion to the substrate and resistance to chemicals or harsh solids. Multi-layer coatings are stronger and subject to less stress than single layer coatings of the same thickness.

The InnerArmor process uses the pipe or process vessel to be coated as the reaction cell. Insulated sleeves link this to the positively charged anodes via which the source gas, at a prescribed temperature and pressure, is pumped through the void. Ionisation of the gas results in even deposition of the coating on the inner surface of the vessel. In addition to protecting the vessel from attrition by the pipe contents, the process can also prevent pipe contents being contaminated by failing pipe material so preserving product quality and value.

Tecvac operate the InnerArmor process under licence from Sub-One Technology of California with whom they share world-wide applications experience. Pipe lengths of up to three metres can be coated effectively as well as pump and piston chambers and other complex shapes. PECVD is environmentally benign, producing no volatile solvents, harmful waste streams, nor requiring high energy input.