A few free tips and good things to know

The choice of steel is not without importance. It has a bearing on the final result.

The silicon content in steel influences not only the thickness of the zinc layer, but ultimately the quality of delivery. DOT is aware of this - which is why the customer should know the silicon contents to have their requirements and wishes for the film thickness after galvanizing fulfilled.

The small details of the construction are important.

That's why we want to be your partner. The small details of hot-dip galvanizing are often:

• Holes must be included for venting and as zinc outlets
• Relief holes must be included in all reinforcing plates
• Holes must be included in welded plates
• Lifting lugs must be included on heavy items
• Cut edges must be rounded

When it comes to painting and metallization, the small details are often:

• Lifting lugs may be included on heavy items
• Cut edges must be rounded

‍

DOT offers advice and guidance already at the project stage.

The steel surface may have a wide variety of impurities or coatings such as paint, varnish, oil, grease, welding slag or welding spray, which cannot be removed by a normal cleaning process.

DOT is happy to be available already at the design stage with guidance, as the more aesthetic quality is important, as the item should appear smooth and free of visible defects — especially where special requirements are imposed on appearance, evenness or the function of the material after hot-dip galvanizing.

Coatings or impurities are presumed to be removed prior to the submission of the item, unless cleaning has been agreed in advance with DOT.

Furthermore, a prior agreement should also be made when items with old zinc coatings are delivered as their removal involves additional costs. This also applies to steel items with particularly severe corrosion (pitting corrosion), paint, lacquer, etc. which must be removed by abrasive blast cleaning or other mechanical cleaning.

It is important that the corrosion protection is intact. Therefore, repair may become necessary.

Performing hot-dip galvanizing and using hot-dip galvanized steel means that there may be a need to repair damage in the coatings.

The need may arise in connection with welding, other finishing, or peeling caused by improper transportation and handling.

DOT offers repair based on one of these three methods:

• Metal spraying with zinc
• Application of zinc rich paint
• Application of low-melting solder zinc

The choice of method depends, among other things, on the corrosion environment and the effects to which hot-dip galvanized structures are subsequently exposed.

The goal is, of course, that the corrosion protection does not deteriorate compared to the original hot-dip galvanizing, and that it at least complies with the requirements set out in the standard DS/EN ISO 1461.