Corrosion – scourge of the seven seas
5 tons of steel are lost every second due to corrosion.
Corrosion therefore weighs heavily on the global economy - heavier than we might think at first sight. NACE's IMPACT study (“National Association of Corrosion Engineers”, USA) calculated in 2016 that 3.8% of our gross domestic product worldwide is spent on preventing or repairing corrosion - more than EUR 500 billion for the European Union only! The impact of corrosion is even greater for specific economic sectors. According to the European NeSSIE project, 18% of the technical operational expenditure (OPEX) of offshore energy production is due to corrosion. For ports, even 19.9% of their turnover would be spent on corrosion prevention and maintenance. In addition, one third of all those costs can be avoided by a smarter, more efficient system to manage the corrosion problem. Investing in more efficient ways to combat corrosion is therefore a sensible choice.
Source: Rob de Vries, Flickr, CC BY-SA 2.0,
And there is more. Steel is a crucial resource for our technological society, and is being used everywhere, in all kinds of constructions: for offshore installations, in ports, in industrial installations ... Making new steel costs a lot of money and takes a big bite out of our energy and carbon budgets. Lastly, corroded infrastructure poses a risk to the safety of personnel in and on those installations, or on board of corroding ships: ninety percent of all ship accidents for example can be attributed to corrosion. The more we can avoid the degradation of steel, the better.
S is for smart sensor system
The first part of this project answers the question of how to measure corrosion. Not that corrosion is not yet monitored today. In many cases this is done by visual inspection, also under water. In addition, there are a number of physicochemical sensors that measure the corrosion rate directly. Most measurement systems are intrusive, such as the use of mass loss coupons, electrical or inductive resistance probes, and electrochemical techniques. Several non-destructive testing techniques exist to detect gaps, weld defects, pitting corrosion on the inside of metal pipes, etc. using electrochemical measurements, X-ray radiography or ultrasonic analysis. Some such sensors are even integrated in the design of some installations, or in concrete with embedded steel.
However, the mere use of a sensor system for corrosion is insufficient. Most of these methods are difficult to follow over a long period of time or require frequent hands-on operation. Also, any monitoring that takes place today measures the effect of corrosion and not the risk: in shipping, sensors only measure the thinning of the ship's wall, and therefore only serve to measure the corrosion a posteriori, not a priori. And finally, corrosion is a phenomenon that can vary greatly from place to place. All of this leads us to conclude that classic corrosion measurements are not sufficient enough to assess corrosion damages and risks.
Is there an alternative way to predict corrosion? Yes and no. Corrosion is a complex phenomenon, driven by the interplay of various physicochemical causes (temperature, pH, salinity, oxygen concentration ...) and modulated by the activity of a large number of bacterial consortia. Trying to untangle this web of possible (co-) mechanisms has never led to a satisfactory answer in the past 2500 years. We therefore want to assess the environment, rather than focusing on the corrosion itself: we use the physicochemical and microbial parameters that determine the environment in which the corrosion occurs, as markers and not as causal factors (a strategy widely used in genetic and biomedical research or in environmental sciences). By measuring the environment, we assess the risk of corrosion.
M is for maintenance management
However, the sensor problem is not the only thing the industry is struggling with, when it comes to corrosion. Anyone wishing to address the corrosion problem must go beyond just installing a set of sensors, supplementing it with a comprehensive, quick and easy management system to measure local physicochemical conditions, perform a risk analysis and to be completed with a life cycle cost analysis. SOCORRO project therefore wants to process sensor measurements with an innovative software package to assess the environment in which corrosion occurs and to calculate a preventive risk from it. Finally, our measurement and management system can then display the risk of corrosion with a "traffic light", with a green, yellow, or red colour code.
Smart management of corrosion – the challenge for the SOCORRO consortium