October 3, 2016

Offshore structures designed for longevity

1. Introduction Apart from their primary role in ensuring long-term protection of surfaces, anticorrosion paints must also be visually appealing in terms of their aesthetics,...

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1. Introduction

Apart from their primary role in ensuring long-term protection of surfaces, anticorrosion paints must also be visually appealing in terms of their aesthetics, identification and security.

Končar – Steel Structures is one of the leading manufacturers of metal structures for the energy sector. The company has successfully profiled itself as a manufacturer of demanding structures for application in harsh corrosive environments, such as offshore, C5 – Marine, coastal areas and areas of high salinity. For this type of product, a profound approach boasting high expertise is what is necessary throughout the entire production process.

Končar – Steel Structures has a broad experience in the production of offshore structures designed to withstand the exposure to external exploitation conditions.

2. Exterior atmospheric corrosion protection

The process of corrosion protection comes at a final stage of the production process, making it prone to compromises because of the pressure and tight deadlines due to the time invested in the previous production stages. The complex demands that are entailed in the production of offshore structures do not provide any scope for poor execution or mistakes since the repair works and the associated costs could multiply the cost of production (by even 100 times in the case of offshore platform structures), in comparison to the costs of the work in the workshop where there is no need for the complex logistics of transferring the workforce, materials and equipment, nor any space or weather condition limitations.

Generally, according to EN ISO 12944, offshore steel structures which are unprotected during the first year of exposure display the following loss of material:

•    Low-carbon steel: 650-1500 g/m² mass loss or 80-200 µm material thickness loss
•    Zinc: 30-60 g/m² mass loss or 4.2-8.4 µm material thickness loss

This is the expected material loss which occurs as a result of the long-term exposure to the moisture of high salinity and an intense UV radiation. Considering that offshore structures are subjected to a dramatic and high corrosion stress which leads to a rapid deterioration of material, they require a proper specification and application of the corrosion protection system. However, this is not the only warranty of the longevity of the corrosion protection. The steel quality and the structural design play an equally important role and may be a critical component in the corrosion processes taking place.

Končar – Steel Structures has recognized and integrated all these aspects in its production processes, thus obtaining the requisite experience in the production of offshore structures. In addition, the company has brought together a team of highly specialized experts in the areas of the construction design engineering, IWE/EWE welding engineering, corrosion protection engineering, which also includes Frosio experts, and certified welders and painters.

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