Materials.Business Newsletter ⚙️ March 27th, 2024
Underneath the surface
From ancient civilizations to modern metropolises, the underground has served as both a sanctuary and a conduit. Yet, beneath our bustling streets lies a hidden danger, silently corroding away at the lifelines of our society. Imagine a world where water gushes forth at the twist of a tap, where gas fuels our homes with warmth and light. Now, consider this: 17% of companies in Colombia battle corrosion in their buried structures, with utilities and oil and gas sectors taking the hardest hit. This isn't just a local issue – it's a global concern.
The Buried Backbone of Civilization
Across Canada, a sprawling network of over 760,000 kilometers of pipelines snakes beneath the earth, quietly ferrying vital resources across vast distances. In the USA, this network stretches a staggering 2.6 million kilometers, equivalent to circling the Earth more than 95 times. These pipelines aren't just conduits; they're arteries, pulsing with the lifeblood of our economy. Yet, they face an insidious foe: corrosion.
The Ethics of Neglect
Buried infrastructure isn't merely out of sight, out of mind – it's a testament to our responsibility as stewards of the earth. Neglecting these assets isn't just shortsighted engineering; it's an ethical failing. As we bury our pipelines and cables, we must not bury our conscience alongside them. Every inch of underground infrastructure carries with it a duty to protect, preserve, and ensure the safety of generations to come.
Unveiling the Corrosive Cauldron
The soil, seemingly innocuous, harbors a corrosive brew capable of eating away at even the sturdiest of materials. Water, air, and earth – the very elements that sustain life – conspire to undermine our buried assets. Microscopic organisms wage a silent war, producing corrosive substances that eat away at metal like acid. Operational mishaps and stray currents add fuel to the fire, hastening the decay of our underground lifelines. Air is what we breathe and is one source of the energy we need (think back to our bodies’ metabolic reactions). The land (i.e., earth) has been the conventional factor of essential product generation. Water is omnipresent, and it permeates air and soil; it is the “greater treasure,” and nowadays is priming to be an issue of business at the New York Stock Exchange.
Now for this next part, let’s recap some of the basics of soil corrosion. In principle, the established electrochemical corrosion cell is simple: the material at risk acts as a cathode, and the water in the corrosive soil as the electrolyte. And the corrosion trend is closely related to the homogeneity degree of the system. As usual, the point of anticorrosive measures is to either break or modify that cell.
Image generated with AI - prompt: An anode, A cathode, An electrolyte, and corrosion.
Of course, the nature of the asset’s material is relevant; for example, other than just the composition, the homogeneity of the surface at the macro and micro levels can influence the establishment of macro galvanic cells, or localized dissolution and pitting appearance due to non-metallic inclusions. Other characteristics concern the assets’ interaction mode due to the regular long-time exposure (i.e., many decades) in these corrosive environments. However, most of the complexity of corrosion problems' comes from the soil’s traits and its variable heterogeneity. Corrosion rates are non-linear, and the problem is multivariate. Additionally, we found limitations in its study because of the unavoidable alterations during the intervention. From this point of view, we can discuss the following three kinds of soil factors that influence the corrosion of buried assets, most of them are interconnected:
Physical-chemical: This involves weathering factors, aeration level (including atmospheric gases like O2, CO2, H2S, and nitrogen and sulfur oxides), water content (including extreme situations such as mud and permafrost, and variability of the water table), pH (where mineralogical composition plays a remarkable role), texture (i.e., the ratio between sand, silt plus clay), soluble salts, resistivity, redox potential, and magnetic fields and their anomalies.
Microbiological: Here, we need to mention three kinds of microorganisms. The first one has a direct effect on the corrosion cell reactions (e.g., the sulfate-reducing Bacterium Desulfovibrio desulfuricans); the second microorganisms affect organic protective coatings (e.g., cellulolytic bacteria, able to deteriorate some kinds of cellulosic coatings), and lastly, the third microorganisms produce corrosive substances (e.g., Thiobacillus thiooxidans, generating H2SO4 as a byproduct of its growth).
Operational: This includes galvanic pairs (accidental or not, even kilometers wide), stray currents (unsuspected most of the time), burial depth, accidental intervention on the buried asset, and contamination (e.g., fertilizer, accidental spills, but also industrial wastes, including nuclear; moreover the increasing risk of deposits of atmospheric pollutants like the underground CO2 storage technologies that have been proposed currently).
Consequences of the corrosive attacks by soil include generalized corrosion and the pitting mentioned above. However due to the cited factors, the galvanic attack is typical, and concentration cells often happen. Thus, crevice corrosion becomes another common mechanism of asset deterioration. Furthermore, stress corrosion cracking is usually found, and sometimes the dealloying mechanism of attack also appears. In these cases, it is mainly cast iron pipes with free graphite as a microstructural constituent that are prone to such phenomenon, undergoing the so-called graphitic corrosion.
Fortifying Our Foundations
But all is not lost. Through a combination of foresight, innovation, and ethical resolve, we can fortify our buried infrastructure against the ravages of corrosion. Predictive modeling, standardized practices, and advanced inspection technologies offer a glimmer of hope in the darkness. Cathodic protection systems stand as bulwarks against the corrosive tide, while meticulous design considerations minimize the risk of galvanic corrosion and stray currents. Assessing the assets with a life cycle mindset is the KEY factor here!
Seizing the Opportunity
As President Biden unveils a historic $5 billion investment in infrastructure projects, including vital bridge replacements and rural developments, we're reminded of the power of collective action. Across the globe, over $720 billion is earmarked for natural gas infrastructure, signaling a continued reliance on fossil fuels. Yet, within this challenge lies an opportunity – an opportunity to innovate, safeguard, and build a future where our buried infrastructure stands as a testament to our resilience, not our neglect.
Conclusion
The need further than the spirit of exploration, colonization, and innovation instinctive to humans forces us to imagine that we will significantly increase subsoil use shortly. In addition, the soil environment’s complexity is a true challenge for corrosion engineers and a physical barrier for inspection, maintenance, and repair. In conclusion, there are more than enough reasons to consider the importance of taking advantage of emerging technologies for a deeper scientific understanding and management of buried assets’ integrity. For example, we have a Ph.D. thesis modeling the soil’s resistivity and pH in the province of Buenos Aires, Argentina. Still, such studies are few and usually restricted to relatively small areas because of practical limitations. Fortunately, researchers have started to approach the problems of corrosion by soils using new technologies. To positively highlight this, a recent paper talks about estimating the corrosion growth rate for underground pipelines, using tools like data analytics, neural networks, geospatial positioning, and, in conclusion, integrating machine learning and geographical information systems (GIS). Undeniably, taking advantage of these new tools and others (e.g., nanotechnology, sensors, robotics, biomimetics, and augmented reality) will pave the route to finding solutions such as monitoring techniques, self-made maintenance, self-repairing materials, and so on. The earth beneath our feet holds both promise and peril. As we navigate the complexities of corrosion and infrastructure, let us not forget our duty to protect and preserve. Through collaboration, innovation, and unwavering resolve, we can ensure that our buried assets remain not just relics of the past, but beacons of a brighter future.
Women in Engineering Summit, Infinity Growth and Materials.Business are celebrating together the Corrosion Awareness Day 2024
At Materials.Businness and Infinity Growth, we are beyond happy to support WES - Women in Engineering Summit! Great collaboration has begun. Our first activity together will be, celebrating the Corrosion Awareness Day 2024 on the 24th of April. Click "register now" to participate.
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