Zinc’s unique property to protect iron and steel from corrosion has been long recognised, with the first British patent for the process of galvanizing dating back to 1837.
Records show that the first commercial use of galvanized metal sheets in the UK was for the Royal Navy at Pembroke Docks in South Wales in 1844.By the end of the 19th century the handling of crude iron and steel sheets in and out of pots or baths of molten zinc by men and youths using steel tongs had become a commonplace practice.
The growth in demand for hot dipped galvanized steel sheets in the early part of the 20th century was considerable with large quantities shipped abroad to all parts of the Commonwealth, Europe, the Middle East, India, Pakistan, China and South America. By the late 1920s, however, the expanding car and consumer products industries were requiring a thinner gauge product with improved surface quality and greater malleability.
The manually-intensive process of galvanizing steel sheets remained virtually unchanged until the mid-1930s when a Polish engineer, Sendzimir, developed a continuous coil-to-coil line along which cold rolled steel strip was acid cleaned and zinc coated for cutting into sheet length and corrugating for added strength.
Such lines, located mainly in large steel making plants, operated into the 1970s when replaced by computer-controlled coil-to-coil lines, operating at high speeds in coating wider, thinner, higher quality steel strip. Those that remain in production today are dual-purpose, being capable of applying pure zinc and zinc alloys.
The post-war demand for a zinc surface more suitable for painting than the normal spangled finish of hot dip galvanized material was met by the development of electrolytic plating, a process whereby a thinner zinc film was applied to produce a rust-resistant matt surface finish. The first sheet plating lines were in time replaced by modern high- volume coil-to-coil lines, no longer in production in the UK.
During the second half of the 20th century, the construction, automotive and consumer products sectors also generated a demand for cold rolled mild steel strip that was zinc coated and either plastic laminated or organic painted, to add colour and extend product life. Many of the organic sheet and coil coating lines installed in the UK have also closed down.
From the 1890s through to today Shotton Steelworks in Flintshire, North Wales, has been at the centre of the galvanizing and organic coating sector, pioneering the development of processes, new products and end uses. Originally known as Hawarden Bridge Steelworks, this still impressive factory was owned by John Summers and Sons Limited until nationalisation of the steel industry in 1967. It has since been part of the British Steel Corporation, British Steel plc (1988-99), Corus Group and from 2007, Tata Steel group.
Between 1989-2002, the site had six coil-to-coil metallic and paint coating lines producing over a million tonnes of coated strip annually. It was the largest operation of its kind in Western Europe. Today, there are three operational coil lines for hot dip galvanizing and organic paint coating, producing around 400,000 tonnes a year.
In 2021, Shotton Works will celebrate the 125th anniversary of its opening and this history is dedicated to the ingenuity and dedication of the thousands of men and women of past generations who worked there and to the hundreds of present-day Tata Steel UK employees on the 500-acre site.
Gordon Smith