How Galvanising Works
Hot dip galvanising protects steel from corrosion by providing a thick, tough, metallurgically bonded zinc envelope, which completely covers the steel surface and seals it from the corrosive action of its environment.
The galvanised coating provides outstanding abrasion resistance. Where there is damage or minor discontinuity in the sealing coat of zinc, protection of the steel is maintained by the cathodic action of the surrounding galvanised coating.
Metallic zinc is strongly resistant to the corrosive action of normal environments and hot dip galvanized coatings therefore provide long-term protection for steel By contrast, most organic paint coatings used on steel need frequent renewal and when coatings are breached corrosion begins at the exposed area of steel, spreading rapidly beneath the coating film.
Spanlift Australia fully hot dip galvanises ALL of our structural steel work, including the roof trusses.
9 Benefits of Galvanising your Structural Steel Shed
The use of galvanising for structural steel protection gives you ten major, measurable benefits.
- Less maintenance/Lowest long term cost. Even in cases where the initial cost of galvanising is higher than alternative coatings, galvanising is almost invariably cheapest in the long term (because it lasts longer and needs less maintenance). And, maintenance causes problems and adds to costs when structures are located in remote areas, and when plant shutdown or disruption to production is involved.
- Long life. The life expectancy of galvanised coatings on typical structural members is far in excess of 50 years in most rural environments, and 20 to 25 years plus, even in severe urban and coastal exposure.
- Reliability. galvanising is carried out to Australian / New Zealand Standard 4680, and standard, minimum coating thicknesses are applied. Coating life and performance are reliable and predictable.
- Toughest coating. A galvanised coating has a unique metallurgical structure which gives outstanding resistance to mechanical damage in transport, erection and service.
- Automatic protection for damaged areas. galvanised coatings corrode preferentially to steel through damage. Unlike organic coatings, small damaged areas need no touch up.
- Complete protection. Every part of a galvanised article is protected, even recesses, sharp corners and inaccessible areas. No coating applied to a structure or fabrication after completion can provide the same protection.
- Ease of inspection. galvanised coatings are assessed readily by eye,and simple non-destructive thickness testing methods can be used. The galvanising process is such that if coatings appear sound and continuous, they are sound and continuous.
- Faster build time. As galvanised steel members are received they are ready for use. No time is lost on-site in surface preparation, painting and inspection. When assembly of the structure is complete, it is immediately ready for use, or for the next construction stage.
- A full protective coating can be applied in minutes; The galvanising process is not dependent on weather conditions.
The Galvanized Coating
The galvanising process produces a durable, abrasion-resistant coating of metallic zinc and zinc-iron alloy layers bonded metallurgically to the steel base and completely covering the work piece. No other coating for steel matches galvanising’s unique combination of properties and advantages:
- For most classes of steelwork, galvanising provides the lowest long term cost. In many cases galvanising also provides the lowest initial cost.
- The galvanised coating becomes part of the steel surface it protects.
- The unique metallurgical structure of the galvanised coating provides outstanding toughness and resistance to mechanical damage in transporterect ion and service.
- The galvanised coating is subject to corrosion at a predictably slow rate, between one-seventeenth and one eightieth that of steel, depending on the environment to which it is exposed.
- galvanising’s cathodic protection for steel ensures that small areas of the base steel, which may be exposed through severe impacts or abrasion, are protected from corrosion by the surrounding galvanised coating.
An inherent advantage of the process is that a standard minimum coating thickness is applied.
- During galvanising the work is completely immersed in molten zinc and the entire surface is coated, inside and out. even recesses and returns which often cannot be coated using other processes.
- Galvanised coatings are virtually ‘self-inspecting’ because the reaction between steel and molten zinc in the galvanising bath does not occur unless the steel surface is chemically clean. It is not possible to have a galvanised coating that is not properly bonded to the surface of the steel. Therefore a
- Galvanised coating which appears sound and continuous is sound and continuous.
- The mechanical properties of commonly galvanised steels are not significantly affected by galvanising.
- Galvanising provides outstanding corrosion performance in a wide range of environments.
Get in touch with our team today to find out more about Hot Dip galvanised Steel in your next shed.
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