MechChem Africa January-February 2023

SA’s nuclear build programme a bonanza for galvanized steel Simon Norton, executive director of the International Zinc Association (IZA) Africa, talks about the proposed nuclear build programme in the SA’s Infrastructure 2050 plan and the opportunities it presents for galvanized steel.

of choice on many steel structures. While i t has been used extens ively in coal , nuclear and natural gas facilities, it is also commonly increasingly finding favour in renewable energy applications, for ex ample as the steel framework for solar and photovoltaic panels and wind turbine pylons. Here galvanized steel, perhaps with a du plex coating system, is ideal for final installa tion in remote locations without any further surface treatment or monitoring, providing immunity to weathering degradation, com patibility with local corrosive conditions, coating toughness and cathodic protection properties that provide steel corrosion protection in tough, arduous conditions, together with minimal maintenance. In terms of power transmission structures, steel has a high strength-to-weight ratio that allows for longer spans without poles that can halt line cascades during severe weather events. Steel pylons are often used in higher voltage transmission lines, but it is nowmore common to see steel distribution poles being used to strengthen a line where longer span lengths are necessary. Zinc galvanized steel has the highest recycled content (93%) of any construction material and has a 98% reclamation rate. Unlike many materials that are down-cycled into a lesser product, zinc galvanized steel is multi-cycled, which means it can be recycled repeatedly without the loss of chemical or physical properties, making it a true cradle to-cradle material. Environmental impact is minimised by utilising natural, abundant, and recyclable steel and zinc. As galvanized steel requires no maintenance throughout the lifespan of an installation, it reduces the carbon footprint significantly. Zinc itself is natural and 100% recyclable with no loss of properties.

Steel structures throughout the power grid require durable corrosion resistant coatings such as zinc galvanized steel to ensure they last for the average 30-to-40-year lifespan.

S outhAfrica’sNational Infrastructure 2050 plan places the spotlight on 9.6GWof newnuclear energy plants converted from decommissioned coal fleet. The procurement rollout is likely to commence with large scale coastal-based reactors and small modular reactors (SMRs) inland on retired coal power station sites and at intensive-energy users. The proposed nuclear build programme presents extensive structural and pres sure vessel supply requirements for South African fabricators and manufacturers, says International Steel Fabricators (ISF) CEO, Neels van Niekerk. The rollout of the programme is expected to deliver an estimated 1 000 MW unit per year for a decade or more. Only about 55% of the total construc tion cost involves the active nuclear island with its top-level certification requirement. The nuclear island is the heart of a nuclear power plant, comprising the containment and auxiliary buildings and fuel handling area. The more conventional turbine island accounts for about 25%, with early works, including accommodation, making up the balance. A typical 1 000 MW plant requires 10 000 tonnes of structural steel for the nuclear island, 150 pressure vessels, 180 storage tanks and 70 tonnes of concrete re inforcing steel. The turbine island requires 7 300 tonnes of structural steel, 130 pres sure vessels, 170 storage tanks, 6 000 tonnes of reinforcing steel and 16 km of piping. The balance of plant equates to 2 500 tonnes of structural steel, 40 pressure vessels, 20 storage tanks, 5 000 tonnes of reinforcing steel and 32 km of piping. In

addition, early works requires 4 000 m of security fencing. This represents a signifi cant opportunity for the increased uptake of zinc galvanized steel, says Simon Norton, Executive Director of the International Zinc Association (IZA) Africa. “The urgent need for additional power generation and distribution infrastructure, including the proposed nuclear build programme, poses a significant opportunity for the industry.” Hot dip galvanized steel plays a criti cal role in corrosion protection in power generation, ranging from transmission and distribution of power to traditional and renewable sources. “In thiswaywe can guar antee the longevity and cost-effectiveness of power projects for future generations,” says Norton. Most power supply steel structures, whether for generation, transmission or distribution, are designed for an average lifespan of 30 to 40 years. These structures are often subjected to a range of arduous atmospheric environments. All steel struc tures throughout the power grid therefore have a need for durable, corrosion resistant and long-lasting protection. Hot dip galvanized steel has been de ployed throughout the power grid for gen erations, as it is the anti-corrosion coating

Hot dip galvanized steel plays a critical role in the corrosion protection of the many structures used in power generation plants.

34 ¦ MechChem Africa • January-February 2023