Corrosion – the gradual deterioration of materials caused by environmental exposure – poses a major challenge in maintaining water distribution systems. To tackle this issue, WISA hosted a seminar focused on understanding corrosion and exploring a range of effective prevention and mitigation strategies.
Peter Fischer from Nicholas O’Dwyer Consulting opened the seminar by covering the definition of corrosion, differentiating it from rust. He provided an overview on the types of corrosion, including:
- Uniform: This occurs evenly across the surface of the metal, making it the easiest to predict and manage.
- Pitting: This is when small holes or cavities appear on the surface of a metal. It is accelerated by chloride ions.
- Galvanic: This occurs when two dissimilar metals are in contact and in the presence of an electrolyte. The more “noble” metal is protected, while the less noble one corrodes faster.
- Stress cracking: This type of corrosion occurs when a metal is under tensile stress in a corrosive environment, leading to crack formation and propagation.
- Microbiological: Microbiological corrosion is caused by the metabolic activity of microorganisms on a metal surface.
Fischer offered practical approaches to controlling corrosion through coatings, linings, resistant materials, and cathodic protection.
Coert Grobler, Corrocoat; Louis Pretorius, Corrosion Institute of South Africa & Corrocoat; Rivaan Ajodapersad, uMngeni-uThukela Water; Craig Botha, Re:ignite; Peter Fischer, Nicholas O’Dwyer; Donovan Styger DENSO
Craig Botha of Re: Ignite presented a study co-authored with Eugene D’Souza and Hasan Sabri of Kuwait Oil Company. The study used low-resistance Sabkha soil, which is found in arid-to-semiarid coastal mudflat or sandflat, where evaporite minerals like salt accumulate due to the fluctuation of high groundwater levels and capillary action. The study tested 3-Layer-Polyethylene (3LPE), a high-performance coating system used to protect pipelines from corrosion and physical damage, and hyper-branched polyurethane. Both coatings had artificial defects, and the study monitored AC/DC densities, coating performance, and corrosion behaviour. The study’s findings showed the importance of anti-corrosion mitigation strategies in cathodic protection.
Botha’s second presentation emphasised the economic impact of corrosion, the role of coatings and linings, CP fundamentals, and anti-corrosion interference mitigation. He stressed the importance of designing for local conditions, including rural and urban contexts, while addressing challenges such as vandalism, theft, and limited specialist capacity. He also highlighted emerging approaches such as the Internet of Things (IoT) enabled monitoring, modular CP systems, and integrated security strategies.
Louis Pretorius, past president of the Corrosion Institute of Southern Africa, detailed the development of DWS 9900 Specification (edition 2). This national specification, which deals with corrosion best practice, was originally meant to replace SANS 1217. It took nearly a decade to be reviewed by the Corrosion in the Water Industry Forum (CITWIF). He also presented on the Lesotho Highlands Tunnel Refurbishment Project, undertaken by Corrocoat. The project rehabilitated over 21,000 m² of transfer and delivery tunnels, requiring extensive logistics, continuous 24/7 operations, and innovative solutions to water ingress and access constraints. The project was completed with a third-party inspection sign-off and no major safety incidents
Rivaan Ajodapersad, from uMngeni-uThukela Water, outlined the operational perspective of asset management. He highlighted the hidden costs of operations and maintenance that depend on the quality determined by the Engineering Council of South Africa’s (ECSA) stages one through six. The presentation included a case study where a 65-year-old bitumen-lined pipeline that is still performing was contrasted with a 12-year-old epoxy-lined pipeline that is failing prematurely. This approach to asset management also details several challenges, such as vandalism of CP units, aggressive soils, and servitude encroachment.
Denso and Corrocaot showcased the latest in anti-corrosion options. Denso showcased tape and epoxy-based systems, including their self-healing visco-elastic Viscotaq technology, while Corrocoat highlighted its global footprint, advanced glass-flake coatings, turnkey anti-corrosion services, and long-life polymer solutions.
Corrosion represents a significant problem if unaddressed, and the seminar reiterated the importance of specifications, the need for proactive asset management, and the role of innovation and training in building a sustainable corrosion management culture.
