Reasons For Hot Dip Galvanizing
1 - Long life
Galvanizing creates an easy-to-clean surface that can give a maintenance-free life of more than 70 years (depending on the environment it is being used in).
When maintenance eventually becomes necessary, it is straightforward. No complex preparation treatments are necessary.
2 - Competitive initial cost
For many applications, the cost of hot-dip galvanizing is lower than that of applying alternative coatings.
The reason is simple: alternatives, particularly painting, are highly labor-intensive compared to galvanizing, which is a highly mechanized, closely controlled factory process.
3 - Lowest lifetime cost
Low initial cost and long life make galvanizing the most versatile and economic way of protecting steel for long periods.
The benefits of no maintenance, or extended maintenance intervals, include fewer problems of access in remote areas, difficult terrain, when buildings are closely packed together, or when there are safety restrictions such as electricity pylons.
4 - Reliability
The process is relatively simple, straightforward, and closely controlled. The thicknesses (weights) of coatings formed are regular, predictable, and simply specified.
Hot-dip galvanizing is defined by a single British Standard EN ISO 1461.
5 - Speed of application
A full protection coating can be applied in hours; a complicated paint system can require a week.
6 - Coating toughness
Galvanizing is unique. The hot-dip process produces a coating that is bonded metallurgically to the steel. No other coating process has this feature and, as a result, galvanized steel has by far the greatest resistance to mechanical damage during handling, storage, transport and construction - an important factor where steelwork is to be shipped around the world.
7 - Complete coverage
Because it is formed by dipping steel into molten zinc, all parts of the surface of the steel are coated - inside, outside, awkward corners, and narrow gaps which would be impossible to protect in any other way.
The coating actually tends to build up at vital corners and edges - rather than thinning out as is often the case with brushed, sprayed, and other dipped coatings.
8 - Three-way protection
Galvanized coatings protect steel in three ways:
-- The coating weathers at a very slow rate, giving long and predictable life.
-- The coating corrodes preferentially to provide cathodic (sacrificial) protection to any small areas of steel exposed through drilling, cutting, or accidental damage. Scratches are sealed by weathering products from the zinc.
-- If the damaged area is larger, the sacrificial protection prevents the sideways creep of rust which can undermine paint coatings.
9 - Ease of inspection
Galvanized steel simplifies the inspection of the protective finish.
The nature of the process is such that if the coating looks continuous and sound, it is!
Thicknesses - simply specified through EN ISO 1461 - can be easily checked with an electronic probe.
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