Bulk transportation of CO2 and hydrogen is a crucial development to reach net zero by 2050.
While using natural gas transmission pipelines is a straightforward and cost-effective solution, these pipes suffer (i) strong corrosion from carbonic acid when transporting CO2, and (ii) accelerated fatigue crack growth when hydrogen is blended with natural gas, even in small percentages.
A thin multilayer coating made of aluminum and aluminum oxide, developed at MIT, can protect these pipes from internal corrosion and fully block hydrogen from reaching the steel. The corrosion protection comes from the stability of aluminum oxide within a pH range of 4.0 to 8.9, covering most oil and gas products transported via pipes. The hydrogen permeation barrier effect is due to the formation of extended space-charge zones at the metal/oxide interface, which repel incoming positively charged hydrogen ions diffusing in the oxide layer. The aluminum interlayer provides compatibility between pipeline steel and the oxide layer, improving adhesion and preventing delamination. The multilayer composite structure offers strong micro-cracking resistance and self-healing potential. Additionally, the non-polymeric nature and ultra-low thickness of the coating make it long-lasting and compatible with current in-line inspection technologies.
The study introduces the SputterPig, a smart tool designed to apply the multilayer coating on the internal surface of natural gas transmission pipelines via magnetron sputtering. In collaboration with Starfire Industries and N2 Solutions, the SputterPig enables coating application through a vacuum-based technology without disassembling the pipeline.
The study also presents results from DNV studies on the coating's effectiveness in reducing internal friction and lowering operating expenses, along with preliminary results from testing conducted at Southwest Research Institute and Louisiana State University.