Comparison of cold galvanizing and other methods of corrosion protection
Various compositions and coatings used in cold galvanizing effectively protect metal structures from corrosion and have many advantages over other methods of protection. To demonstrate the full benefits of cold galvanizing, we make detailed comparisons with the most common corrosion protection methods such as hot-dip galvanizing, painting and plating.
Comparison of cold galvanizing and hot dipping
1. Compositions and coatings of cold galvanizing have the ability to form galvanic vapors,
the frequency level of zinc particles is up to 99.9%, and the zinc content in the film is up to 96%, which is identical to the results of hot-dip galvanizing. However, the costs for the composition and the coatings themselves, as well as for the work on galvanizing, differ significantly from the prices for hot-dip galvanizing. The use of cold galvanizing of any structure, even the largest structure, will cost you several times cheaper than hot-dip galvanizing.
2. The service life of a cold-dip galvanized or hot-dip galvanized coating is also the same, but after some parts of the surface have lost zinc and have lost their corrosion protection, it will be possible to “fill the holes” with cold galvanized, which means that surface repair will be necessary only for a specific area, not the entire structure. In addition, the difference between new and old galvanized areas will hardly be visible, since the coating “mixes” well with the old layers. Hot-dip galvanizing should not be carried out only in certain areas of the structure.
3. Cold-galvanized coatings form a reliable and durable electrochemical bond with the metal to which they are applied, so that the coatings do not flake off, but flaking is possible with hot-dip galvanizing.
4. Layers of cold galvanized compositions can not only withstand high temperatures up to 150 ° C, but can also be applied down to -30 ° C.
5. “Cold” coatings resist thermal expansion and contraction without damage because they are elastic. They can “survive” the mechanical deformation of the structure itself up to 5 cm per 1 m without losing their protective properties.
6. Application of cold galvanizing compounds can be done almost anywhere and requires only one person to work, which significantly reduces costs compared to hot-dip galvanizing, which is performed only by a team of specialists in designated areas.
7. Cold galvanized coatings can be applied to damp surfaces.
8. Unlike hot dip galvanizing, which requires removing old layers, cold galvanizing can be applied to old layers.
9. If there are no traces of old paint, grease, oil and rust on the surface, then cold-galvanized materials can be used without special, complex and expensive surface treatment.
10. Zinc filled joints with good surface preparation have an adhesion point of 1. At present, hot-dip galvanized compositions cannot boast of such an indicator.
11. Hot-dip galvanizing requires immersing the structure in a special bath at very high temperatures. This can lead to deformation of the structure, which can cause difficulties in assembly and installation. In addition, some structures cannot be delivered to the desired location and immersed in the bath due to size and immobility. These problems do not occur with cold galvanizing.
Cold galvanizing and painting
Zinc paints have a similar composition and methods of exposure to compositions for cold galvanizing and, therefore, have many of the same advantages, but cold galvanizing still has some advantages over paints.
1. Cold zinc plating often dries much faster than plain paints, which speeds up the process. After application, it is possible to apply a second layer in an hour. And paints are used as an additional surface coating.
2. Cold galvanized coatings can be applied to already rusty surfaces without any special treatment, which many paints do not allow.
3. “Cold” formulations can be applied to damp surfaces.
4. Can be applied over old galvanized coatings.
5. Cold-galvanized coatings provide reliable cathodic protection of welded joints most susceptible to corrosion.
Cold galvanizing and plating
1. All cold-galvanized compositions have the same reliable cathodic protection capabilities, which is equivalent to metallization.
2. There are a large number of complex and not always feasible requirements for the preparation and use of structures for metallization. For example, non-wet abrasive blasting, Sa 3 grade, exclusively dry sandblasting. The metallization process itself must be carried out immediately after processing, no later than 6 hours if the structure is indoors, and no later than 30 minutes if the structure is outdoors. The room in which the process takes place must be well ventilated, and