When? Where? How?
Hot dip galvanizing is mainly used in corrosive environments, like corrosion category 2 to 5 acording to
EN ISO 12944-2, but can also be used in less severe environments, for example indoors.
Below advises about which types of surface coatings that can be used in different environments are given.
An comparement between their advantages and disadvantages are also shown.
COMPARISON BETWEEN DIFFERENT ZINC COATING METHODS
| Hot dip galvanizing | Electroplating | Zinc spraying | |
| Coating thickness | 70 - 215 µm | 3- 12 µm 1) | 40 - 200 µm |
| Standard | EN ISO1461 | ISO 2081 | 2972 |
| Adherence | Alloying with the steel | Electro-cemical | Mechanical |
| Application | Dipping in melt zinc | Electrolytic deposit | Spaying of molten zinc droplets |
| Appearance | Shiny and/or gray | Shiny | Light gray |
| Finish | Good | Very good | Good |
| Spread in thickness | Low | Medium 2 | Higher 3 |
| Coating inside cavities | Yes | No | No |
| Outdoor protection 4) | Very good (25 - 75 years) | Bad (1 - 6 years) | Good (10 - 50 years) |
| Quality control | Easy | Easy 5 | Easy 5 |
| Upper size limitation | Around 25 m in Norden | Around 6 m in Norden | No limits |
| Lower size limitation | 3 mm wood screw | Approximately 2 mm | Heavy enough for the spray pressure. |
Use of coated product |
Utedoor when long lifte time is required | Indoor or outdoor during shorter periods | Utdoor |
| Life time cost | Very low | High | Low |
| Cathodic protection | Very good | Limitid | Good |
| Deformation during application | May occur 6 | No | No |
1)
Thicker coatings may be created, but those will be more expensive to create
than corresponding hot dip galvanized coatings.
2) Depends on electrode positions.
3) Operator dependent.
4) Local variations may occur.
5) More mesurements are required.
6) Internal stresses in the steel may be relaxed in the
galvanizing bath.