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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 Ám 3- 12 Ám 1) 40 - 200 Ám
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.