Thermal spraying extends life span and maintenance intervals

This year, FSP conducted a big thermal spraying project in their Pori, Finland, paint shop. The project consisted of 132 steel segments, which were transported into Norway after assembly, to be used as part of the foundations of wind turbine power stations in the North Sea.

The foundations of a wind power plant are constructed from four segments. According to the area manager of FSP, Miikka Kuutilo, the goal of the surface treatment is to protect steel structures from salt water corrosion and prevent abrasion corrosion, as the structures will be used in highly extreme circumstances in the Norwegian North Sea.

Kuutilo describes thermal spraying as one of the most diverse industrial surface treatment methods, and that it’s also in high demand because it offers a wide selection of coating materials, among other things. The main goal is to extend the life span and maintenance intervals of the product.

“Thermal spraying provides steel structures with excellent qualities compared to other types of technical applications. Such qualities are, on top of the corrosion-protection, resistance to abrasion, hardness, thermal conductivity, heat durability and adhesive strength as well as its suitability to be used for large surfaces,” Kuutilo describes.

Expansion to several sectors of industry

Thermal spraying can be used to enhance the electrical conductivity or -insulation, lubrication, friction, chemical durability and other qualities of treated objects.

The advantages of the procedure, according to Kuutilo, are also the great speed of manufacturing, low heat input into the work-piece and reasonable surface treating costs compared with other applications.

Due to its versatility, thermal spraying has spread to a number of industries. In several countries, it generally is now a industry demanded surface treatment method. It can be used for bridges, cranes, ships, off-shore-platforms, port facilities, oil rigs, fences and gates as well as vehicles, among other things.

In thermal spraying a solid metal is melted down and sprayed onto the surface of a given object, which will form a surface coating of uniform quality and high durability.

Strict quality control

The whole coating process consists of preliminary preparation of the surface to be coated, spraying, sealing and finishing. A thermal spraying process demands a strict quality control according to standards.

Before the actual coating, the suitability of the steel structure will be checked through for the used method. The workers will diligently clean out all grease and contaminants. After the abrasive blasting the surface roughness, the absence of dust and the rest of the surface profile will be checked.

Also, it will be made sure, that the oxide layer has been removed from the metallic surface, meaning that it is in an active state. The surface temperature must be sufficiently over the dew point.

Sufficient smoke exhaust will ensure, that a harmful dust layer will not accumulate onto the surface during the coating. After thermal spraying the work quality will be assessed visually both with a film thickness measurement and a pull-off test.

Wind turbine flanges received durability

During the last year FSP has also done another demanding surface coating project in Pori using thermal spraying. The objects of thermal spraying were wind turbine flanges, which were also given a zinc coating.

The wind turbine flanges are part of the new Pori Tahkoluoto wind park ocean foundations. FSP conducted the work in western Finland, in Mäntyluoto, Pori, for Technip Offshore Finland Oy, which manufactures oil rigs, among other things.