New coating technology promises doubled lifespan for equipment

Corrosion and wear are common, persistent problems plaguing a wide range of oilfield equipment, but a new interior coating technology offers a unique solution. The InnerArmor system, developed by materials-science specialist Sub-One Technology, promises to double the operating life of equipment while also reducing in-line pressure loss and improving flow dynamics.

InnerArmor employs a technique known as Hollow Cathode Plasma Immersion Ion Processing (HCPIIP) to apply extremely hard, smooth, corrosion- and erosion-resistant films on the interior surfaces of parts, from pumps to drilling equipment. In this process, a gas-phase chemical precursor is introduced into the internal space to be coated, and then hollow-cathode technology creates rapidly pulsed fields that ionize the particles and cause them to uniformly deposit onto the internal surface. The result is an extremely hard, hydrophobic (water-repelling) surface.

The films created by HCPIIP are reportedly amorphous like glass, with no crystalline grain structure and no porosity. During the application process, the film is inherently self-leveling, which provides for smooth and uniform coverage across long lengths of steel tubing and over complex geometries. Pinholes or bare spots are reportedly eliminated, which provides an additional benefit over epoxy coating or similar treatments.

The coatings adhere strongly to metal surfaces and are very hard, exhibiting a four-order-of-magnitude improvement in wear resistance vs. uncoated stainless steel in laboratory tests performed by Sub-One.

In terms of corrosion resistance, the coating technology passed the NACE-standard TM185 sour autoclave test for 30 days with no attack or undercut of coating observed. In the same test, uncoated steel showed evidence of attack after one day.

InnerArmor films also reportedly have a very low coefficient of friction (more than 100 times lower than uncoated steel in Sub-One lab tests). This, coupled with their hydrophobic nature, means that liquids slide quickly across the coated surface, which improves flow dynamics and reduces in-line pressure losses. This improves project and operating costs by allowing operators to downsize their pumping requirements, use smaller-diameter pipe to transport the same volume of fluid, and use less expensive alloys as starting materials.

Sub-One reports that coating strength can be manipulated by choosing different ionizable starting materials, and corrosion resistance can be increased by laying down a thicker film.

The California-based company has entered into several licensing agreements for InnerArmor, including one with Houston-based Houston Plating & Coatings and another with Aberdeen-based Advanced Coatings Initiative (ACI). The latter agreement is the first with a European distributor, and ACI is touting the potential savings in terms of increased operating cycles, improved productivity, and decreased maintenance costs to its clients operating in the North Sea. The company has also recently installed two coating machines in its Portlehen, Aberdeen, facilities to supply the North Sea market.

Visit Sub-One's website to learn more about this coating technology.

Ted Moon is the Technology Editor of JPT Online. He brings information on emerging technologies, R&D successes, new field applications, updates from SPE papers about recent innovations, and more. If you have a question or suggestion for future article topics, email Ted at teched@spe.org.