Researchers at the U.S. National Energy Technology Laboratory (NETL) (Washington, DC, USA) have developed a self-healing cold spray coating, which they believe can provide corrosion protection against the interior of natural gas, hydrogen, and carbon dioxide (CO2) pipelines.
According to NETL’s Ömer Doğan, who worked on the innovation with a research team comprised of Joseph Tylczak, Margaret Ziomek-Moroz, Zineb Belarbi, and himself, internal pipeline corrosion is a common problem in the industry.
“Internal corrosion in pipelines primarily is due to the presence of water, carbon dioxide, and hydrogen sulfide contained in natural gas,” Doğan explains. “Internal corrosion can eventually result in leakage, cracks, and a rupture of the pipeline … leading to explosion hazards and methane emissions.”
Traditional approaches to fighting pipeline corrosion have long included the use of inhibitors or organic coatings, such as fusion-bonded epoxy and polyurethane. However, injecting inhibitors in natural gas or CO2 pipelines is challenging because of the difficulty of transporting the inhibitor along the pipelines, according to NETL.
Meanwhile, the main disadvantage of using organic coatings is that they have poor abrasion resistance and can form a corrosion focal point.
According to Doğan, another approach is to use sacrificial coatings to protect pipelines and equipment from internal corrosion. A sacrificial coating, or anode, undergoes oxidation more than the metal surface it protects. In turn, this effectively stops oxidation on the metal. However, the existing sacrificial coatings tend to dissolve too fast in natural gas pipelines, NETL explains.
“The invention consists of a new zinc-rich material that creates an effective protective layer, which resists dissolution compared to existing zinc sacrificial coatings,” Doğan says. “This new material can be applied to steel structures in a cold spray process to protect them from the effects of corrosion.”
How Cold Spray Works
NETL describes cold spray as a high-energy, solid-state coating and powder consolidation process for the application of metals, metal alloys, and metal blends. It can be used for numerous applications.
The cold-spray process works by using an electrically heated high-pressure carrier gas, like nitrogen or helium, to accelerate metal powders through a supersonic nozzle for particle adhesion. The coating can then be applied to a pipeline’s interior by using a robotic cold-spray device attached to a pipeline pig.
Relative to existing approaches, NETL says other features and advantages of the zinc-rich coating approach include its ability to:
- Remain stable regardless of changes to the temperature or pressure of the service environment;
- Not form defects during cold spray deposition, resulting in extended life;
- Self-heal when damaged by forming protective corrosion products;
- Not require a periodic application process;
- Be used as structural material to repair a used or damaged pipeline.
A Report of Invention was officially disclosed on June 30, 2023, with 23N-12 as its assigned label. More information on this innovation and related research can be obtained at NETL’s web site.
NETL is a U.S. Department of Energy national laboratory designed to drive innovation while delivering technological solutions for an environmentally sustainable and prosperous energy future.
By leveraging world-class talent and research facilities, NETL says it aims to ensure affordable, abundant, and reliable energy to drive a robust economy and national security. The group also strives to develop technologies to manage carbon across the full lifecycle, thus enabling U.S. environmental sustainability.
NETL’s project portfolio includes research and innovation conducted through partnerships, cooperative research and development agreements, financial assistance, and contractual arrangements with universities and the private sector. Together, these efforts focus a wealth of scientific and engineering talent on creating commercially viable solutions to national energy and environmental problems.
Source: NETL, https://netl.doe.gov.
Editor’s note: This article first appeared in the December 2023 print issue of Materials Performance (MP) Magazine. Reprinted with permission.