The long-term durability provided by galvanizing is achieved at relatively low environmental burden in terms of energy and other globally relevant impacts. The life and durability of steel are greatly improved when coated with zinc and no other material can provide such efficient and cost-effective corrosion protection.
Galvanizing steel provides a ‘once – only’ solution
Hot Dip Galvanizing Corrosion Map of UK and Ireland
Atmospheric corrosion rates have been mapped across the UK and Ireland and our latest corrosion map shows that batch galvanised steel can today provide a ‘once only’ corrosion protection solution for steel. Our latest Corrosion Map shows that an 85μm hot dip galvanised coating can provide between 34 – 174 years of protection to steel across the UK and Ireland.
Galvanized coatings stop corrosion of steel in two ways – a physical barrier and electrochemical protection. The coating provides a continuous, impervious metallic barrier that does not allow moisture and oxygen to reach the steel. The coating reacts with the atmosphere to form a compact, adherent patina that is insoluble in rainwater.
Typical coating thicknesses can range from 45μm to over 200μm. Research over many years has shown that the life of this barrier protection is proportional to the zinc coating thickness. In other words, doubling the coating thickness will double the life of the coating.
Galvanic (Sacrificial) Protection
Zinc corrodes in preference to steel and sacrifices itself to protect the steel, hence hot dip galvanizing will provide this sacrificial protection.
Zinc will also galvanically protect steel. When bare steel is exposed to moisture, such as at a damaged area, a galvanic cell is formed. The zinc around the point of damage corrodes in preference to steel and forms corrosion products that precipitate on the steel surface and protect it. There is no sideways corrosion at points of damage.
In addition to being long lasting, galvanized steel will withstand multiple lifecycles of reuse. This feature is well illustrated by the growing use of demountable structures such as temporary parking systems, which are rapid to construct, easy to dismantle and which can be used again or stored for future use. Being tough, abrasion resistant and highly durable, a hot dip galvanized coating will accompany steel components through their multiple lifecycles.
Durability of Galvanized Steel – Case Study
Location: Nottingham University
Architects: Michael Hopkins and Partners
When constructed, Jubilee Campus coincided with Nottingham University’s Centennial Jubilee in 1999. The unique, freestanding circular learning resource centre and conical lecture halls made full use of their lakeside setting. The design included a sophisticated natural ventilation system for its time.
Images © Simon Congdon.
More than two decades after construction, both the design concept and material choice are faring well. The cedar has matured and portrays a rich texture alongside the patinated galvanized steel that frames it. Although not immediately obvious, the presence of gently weathered galvanized steel is also evident in many other areas throughout the campus.
Read more about the project
You may also be interested in: