The Prevention of Corrosion
When iron is extracted from its ore, a fundamental tendency of nature is abruptly reversed. Unless protected, iron and steel will corrode in most environments, slowly returning to their natural state.
Corrosion prevention is an essential factor in the economic utilisation of steel. Provision of the appropriate protective coating can bring initial savings plus substantia! economies in service, due to reduction or elimination of maintenance and lost service time, and by deferring the replacement date of structures and equipment.
Galvanizing provides ideal corrosion protection for steel - no other coating matches galvanizing's unique combination of low first cost, ease of inspection for coating quality, durability, predictable performance, low maintenance, and resistance to abrasion and mechanical damage.
Hot dip galvanizing protects steel from corrosion by providing a thick, tough metallic zinc envelope, which completely covers the steel surface and seals it from the corrosive action of its environment. The galvanized 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 cathodicaction of the surrounding galvanized coating.
The Benefits of Galvanizing
No other coating for steel matches galvanizing's unique combination of properties and advantages. These include:
- For most classes of steelwork galvanizing provides the lowest long-term cost. In many cases galvanizing also provides lowest initial cost.
- The galvanized coating becomes part of the steel surface it protects.
- The unique metallurgical structure of the galvanized coating provides outstanding toughness and resistance to mechanical damage in transport, erection and service.
- The galvanized 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.
- Galvanizing's cathodic protection for steel ensures that small areas of the base steel exposed through severe impacts or abrasion are protected from corrosion by the surrounding galvanized coaling.
- An inherent advantage of the process is that a standard minimum coating thickness is applied.
- During galvanizing the work is completely immersed in molten zinc and the entire surface is coated, even recesses and returns which often cannot be coated using other processes. If required, internal surfaces of vessels and containers can be coated simultaneously.
- Galvanized coatings are virtually 'self-inspecting'because the reaction between steel and molten zinc in the galvanizing bath does not occur unless the steel surface is chemically clean. Therefore a galvanized coating which appears sound and continuous is sound and continuous.
- Galvanizing is a highly versatile process. Items ranging from small fasteners and threaded components, up to massive structural members can be coated.
- The mechanical properties of commonly galvanized steels are not significantly affected by galvanizing.
- Galvanizing provides outstanding corrosion performance in a wide range of environments.