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New Techniques for Tackling Corrosion: As the saying goes, rust never sleeps, but mine and plant operators are waking up to new technologies for controlling it.

From a global mining viewpoint, corrosion of materials and equipment might best be described as a universal problem that demands localized solutions. Differences in ore characteristics, extraction processes and chemicals, or environmental conditions mean that a corrosion-preventative product that works well at one site might be less effective at another.

Although there are plenty of products available to help solve the industry's corrosion concerns, it can be expensive to sink money into a one-size-fits-all solution that doesn't meet the specific conditions of a particular problem. Experts say there is no simple rule of thumb for selecting the most suitable coating product or system. Taking into account the many factors that promote corrosion requires a disciplined approach to solve--or at least manage--corrosion problems.

The recommended and most cost-effective approach is to study a corrosion problem first before choosing a product. Use tools currently available from suppliers and professional organizations to identify the cause and develop a solution. These range in complexity and scope from simple inspection checklists that can be completed by an on-site employee and used by suppliers to recommend an appropriate product; or material and corrosion mapping audits conducted by specialist organizations; to top-down, enterprise-wide corrosion studies and action plans. It's been estimated that up to a quarter of all industrial corrosion problems could be prevented by employing established, well-documented techniques.

Combining Technology and Management

One of the most ambitious recent efforts to organize and simplify corrosion management and prevention began in 2014 when NACE International conducted a global study designed to go beyond the economic effects of corrosion. It focused on how to integrate corrosion technology with organizational management systems. NACE, a professional organization headquartered in Houston, Texas, USA, and originally founded as the National Association of Corrosion Engineers in 1943, is considered an authoritative source for corrosion management training and technology, with about 36,000 members in 130 countries.

IMPACT--The International Measures of Prevention, Application and Economics of Corrosion Technologies was released in 2016. One of its most significant findings was that the global cost of corrosion at the time amounted to an estimated $2.5 trillion, which was equivalent to 3.4% of the global Gross Domestic Product (GDP) at that time. The study determined that reducing the astoundingly high cost of corrosion would require a change in how decisions are made. For example, while it is important to continue investing in technology for corrosion control, putting this technology into an organizational management system context and justifying corrosion control actions by business impact is essential.

Building on the study's findings, the NACE International Institute (NII), an affiliation of NACE International focused on helping companies improve their performance with corrosion management systems and certification of personnel, started development of a platform to benchmark practices and improve corrosion management across all industry sectors.

"Soon after we released the IMPACT study, we began to hear from respondents and focus group participants that they needed tools to put the report's findings into practice," said Elaine Bowman, IMPACT PLUS project manager. "They couldn't find any products to facilitate improved practices and asked us to develop a process that would help their companies manage, monitor and improve their corrosion management activities."

Working with the American Productivity & Quality Center (APQC)--which specializes in benchmarking, best practices, process and performance improvement, and knowledge management. NII developed IMPACT PLUS, released in December 2017, as an online network of tools, including a customized corrosion management process classification framework, corrosion management maturity model, and an extensive reference library.

IMPACT PLUS users have the option to manage their own use of the product or work with a trained navigator with corrosion management and consulting expertise. Navigators help customers evaluate and compare their current asset management processes and advise them on future asset protection and corrosion management strategies.

IMPACT PLUS offers a wide range of features, according to its developers, including:

* An integrated platform for corrosion management professionals;

* A common language and structure needed to ensure communication throughout all levels of an organization;

* A straightforward way for companies to identify gaps in processes that could lead to the reduced lifecycle of assets due to mechanical, integrity or human error;

* A Corrosion Management Maturity Model that creates a roadmap of activities, investments, and best practices that lead to higher performance;

* A Corrosion Management System Framework, which is an organizational structure that enables effective corrosion mitigation while providing a positive return on investment; and

* A reference library to manage knowledge and information collected through all components of the portal.

Going Digital

Other companies are pursuing digital solutions for controlling corrosion, offering solutions largely drawn from technologies used in the petroleum/gas sector where corrosion can lead to disaster. For example, Accenture offers "digitally enabled" corrosion management services and solutions that employ a three-pronged approach involving IoT, data visualization and advanced analytics to help companies achieve optimum asset value several different ways. This includes through increased certainty of zones/lines at risk; reduced scope and frequency of inspections; reduced cost and asset downtime due to inspections; increased asset life; and improved worker safety. According to Accenture, these improvements can provide a 10-20% reduction in inspection costs, 10% or more increase in uptime and productivity, and improved asset integrity, increasing asset life by more than 20%.

Services available through Accenture's program include:

* Risk-based inspection methodology;

* Asset integrity division readiness;

* System and data integration enabled by its Data Analysis and Processing Tool (ADAPT);

* Image and video analytics to detect surface defects and signs of corrosion;

* Advanced analytics and deep learning using maintenance, design, operations, environmental and historical data;

* Real-time, interactive equipment monitoring by combining 3D modeling with its Active Network Model for Corrosion Management; and

* Digital inspection technologies, including nanotechnology, ultrasound, laser spectrometry and optical non-destructive testing.

GE Inspection Technologies also said it is developing a family of corrosion management and inspection tools, with initial focus on corrosion monitoring. Its first product in this area is a predictive corrosion management application running on GE's Predix platform and utilizing RightTrax PM ultrasonic sensors installed to provide coating-thickness monitoring. This approach, said GE, offers real-time thickness measurement and the ability to perform advanced data analytics and visualizations. It will allow users to move from point-in-time to continuous thickness measurement, and thus enable customers to improve asset integrity management while opening the door for innovative ways to utilize this data to optimize plant and process performance.

Picking the Perfect Product

A quick scan of the list of available corrosion-preventative coating types illustrates the potential difficulty of selecting the right product for a specific problem. Common coatings, for example, include cross-linked or thermoset coatings, epoxy resins, polyurethane resins, alkyd resins, inorganic resins and thermoplastics, among others--and each of these categories has certain benefits and application requirements. Specific products within each category may have their own subset of features, intended usage and targeted substrates. A few examples:

Certain resin types such as polyvinylidene fluoride (PVDF) can be used in sprayable form or molded into various shapes and are now available in powder coatings that offer a new avenue for accessing PVDF's ability to protect metal substrates used in mining and mineral processing from corrosion, abrasion and chemical attack. PVDF, according to suppliers, can succeed in applications where other types of materials such as fiberglass-reinforced plastic (FRP), elastomeric and urethane liners have prematurely failed. Major chemical companies such as Arkema and Solvay market their PVDF products under the brand names Kynar and Hylar, respectively.

Another relatively new type of coating is chemically bonded phosphate ceramics or CBPCs. EonCoat is one of these--a spray-applied industrial coating that prevents rust on carbon steel. EonCoat "phosphates" the steel to which it is applied, forming an amorphous magnesium iron phosphate layer. This layer, chemically bonded to the steel, is the first line of defense against corrosion. A white ceramic layer then forms over the alloy layer. This ceramic layer, the second line of defense, provides a reservoir of phosphate corrosion protection to continuously maintain the alloy layer. The coating was developed and patented several years ago by North Carolina, USA-based EonCoat LLC.

SPI Performance Coating, a U.K. distributor for EonCoat, recently reported that one of world's largest underground mines had used it successfully to extend the life of a troublesome process hopper that handles thousands of tons of iron ore material weekly. Natural salts contained within the material, combined with water condensation, created perfect conditions for corrosion of the hopper's steel components.

Before the EonCoat application could begin, heavy deposits that had built up on the hopper walls had to be mechanically chipped away, followed by abrasive blasting, and then washing with potable water to remove blasting debris from the metal surface. According to SPI, the level of salt content in the area became highly apparent when the hopper's steel began to flashrust minutes after the washing process.

EonCoat CR was applied to the lower section of the steel hopper at a nominal thickness of 800 pm WFT in a single coat, applied over an eight-hour shift. The following morning the entire area was pressure-washed to allow the applicators to determine if the process had been successful. EonCoat simply washes off if it doesn't fully react with the substrate, allowing the applicator to remedy any problems before returning equipment to service, according to SPI. Over the whole area, only three small patches needed reapplication.

SPI reported that, upon inspection, passivation of the steel from formation of magnesium iron phosphate produced no pinholes, voids or delaminations in the finished EonCoat application. This, said the company, is due to the reaction between the acid and base, creating a negative charge within EonCoat CR that physically pulls it into every surface imperfection.

Approaching steel-corrosion problems from a different direction, Fluoramics, a supplier of engineered Polytetrafluoroethylene (PTFE)-based corrosion solutions, announced it now offers a way for metal fabricators and welders to protect steel from corrosion without impairing their ability to weld it. Fluoramics said its HinderRUST S4.0 rust inhibitor recently passed extensive testing at the Welder Training and Testing Institute (WTTI) in Allentown, Pennsylvania, USA, to assure welders that they can weld steel directly through this HinderRUST formulation.

HinderRUST S4.0 is used in the metal fabrication industry to prevent corrosion of steel. Solvent-free S4.0 can be applied to steel parts or plates by brush, roller or aerosol spray can, and it will immediately displace moisture on the treated surface and protect the steel from rust for up to two years.

Fluoramics said it was interested in determining if strong, secure welds can be made to steel treated with S4.0, and consequently had WTTI conduct a series of tests on A/SA516 Grade 60/70 steel of a uniform thickness of 0.375 in. The steel pieces treated with HinderRUST S4.0 passed all tests, including two transverse face bends, two transverse root bends, two tensile strength tests, and both visual and radiographic inspections.

And, under its Master Builders brand, BASF offers MasterProtect 8020CI, a surface-applied corrosion inhibitor that the company said is designed to migrate through even the densest concrete structures and form a layer on the steel reinforcing bars. MasterProtect 8020CI also protects other metals including carbon steel, galvanized steel and aluminum. According to the company, MasterProtect 8020CI will stop the further corrosion of reinforcing metals and extend the service life of the structure.

The principal benefits of MasterProtect 80201CI, according to BASF, include:

* Reduces corrosion rate of corroding steel not yet visible;

* Provides protection in new structures where insufficient cover is an issue;

* Stops the formation of incipient anodes at new to old concrete interface;

* Does not interfere with bond of repair mortars or coatings--can be used directly on areas to be repaired;

* Forms passive layer underneath rust on steel--slows corrosion to allow for longer term repair strategy to be put in place;

* Easy application;

* Water-based;

* Allows concrete to breathe and vapor to diffuse--is not a vapor barrier;

* Dual action inhibitor--protects both anodic and cathodic areas; and

* No cure time required.

Protecting Control Equipment

To be sure, not all corrosion-preventative solutions focus on the steel and concrete substrates that constitute much of the mining industry's asset base. The degradation of electrical control equipment by corrosive gases and substances is a well-known process and, as air filtration specialist Camfil pointed out, heavy industries such as mining are becoming increasingly reliant on electronic and electrical controls for the safe and efficient operation of various--often automated--processes. In many industrial environments, the external air around a facility may contain acidic gases. Plus, fine particles in the atmosphere, containing corrosive contaminants in the form of salts of ammonium and sulfate that retain moisture, may come to rest on control equipment. Either of these conditions can lead to corrosion problems.

Camfil said molecular filtration using adsorption technology is the industry-accepted method to remove corrosive agents from the air. The company's corrosion control solution includes evaluation of a site's environmental conditions; providing filtration solutions in accordance with corrosive-gas concentration levels and the operating conditions of the existing ventilation systems; and on-site performance monitoring, in accordance with applicable standards such as ANSI/ISA-71.04-2013 and IEC 60721-3-3.

Filter supplier AAF Flanders also focuses on the problem, noting that stricter environmental guidelines have forced many manufacturers to replace lead-based solders with lead-free solutions, which are more susceptible to corrosion of circuit boards and components from airborne gaseous and particulate contaminants. These forms of corrosion can cause failure by either impeding the flow of electricity or forming unintended circuit paths.

In response to these problems, the industry has developed a standard to classify control rooms and process control environments. Most equipment manufacturers require that a control room environment meets the ISA G1-Mild classification to maintain a reliable communication network in industrial environments. The only way to meet this requirement in many industrial environments, according to AAF Flanders, is with adequate gas-phase and particulate filtration in control-room spaces.


Caption: The cost of corrosion is usually expressed in terms of 'direct' costs, but the actual number can be much higher when indirect costs are added, such as labor attributed to corrosion management activities; equipment required because of corrosion-related activities; loss of revenue due to disruptions in production; and loss of reliability. (Photo: Chemco)

Caption: This diagram from NACE's IMPACT study illustrates the interaction between corrosion management systems (CMS) and other organizational management systems.
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Title Annotation:CORROSION
Author:Carter, Russell A.
Publication:Coal Age (1996)
Date:Oct 1, 2018
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