TPi November 2016

products & developments Optimising key assets

PPA 571 forms a fusion bonded coating over the metal beneath, producing a thick, flexible coating with long-term protection again corrosion. It has abrasion resistance and does not chip or crack on impact – highly relevant on a rig where heavy components are being shifted around, where storms can throw items against each other, and where rough straps and brackets are frequently attached to posts and railings to secure items. There is no chance of penetration by water, gases or microbes, so degradation does not start underneath the surface as it often does with liquid paint. In tests, PPA 571 has been subjected to over 20,000 hours of salt spray testing with no blistering, cracking or flaking. The flexibility of the coating means that it does not crack, either on bending or at very low temperatures. The smooth, glossy surface provides a low anchor for algae and fungus, so the rate of fouling is slower than with many alternative coatings. The surface of PPA 571 is classed as ‘good grip’ and ‘warm to touch’, making it especially appropriate for safety rails. No primer or galvanising is required for Plascoat PPA 571, and it is a single coating, most frequently applied by fluidised bed or electrostatic spray directly on to the metal. Should the coating become damaged once in situ there are quick and easy repair procedures. If heat is applied to the coating at the edges of the damaged area it will begin to soften. Molten material from a strand or film of PPA 571 can be slowly applied to fill in the damaged area and the coating will re-seal itself upon cooling, leaving no metal surface exposed to the elements. If it is not possible to apply heat then an acrylic polyurethane coating can be carefully brushed or sprayed into the damaged area to create a seal. PPA 571 is BPA free, and contains no VOCs, TGIC, phthalates, isocyanates, halogens or heavy metals. In the event of a fire it has a low burn rate and density of smoke generation, with very low fume toxicity.

anodising, liquid and spray paints and powder coatings. On offshore facilities, paints and coatings are most commonly used in the demanding ‘splash zone’, near water level, and need to be applied with the highest of standards. They must be highly resistant to the environment, have good adhesion, and be abrasion resistant, easily maintained, quick drying and non-toxic. Liquid paints are frequently used but these deteriorate quickly under the challenging conditions. The coating is simply not robust enough. The smallest cracks or chips in the paint will allow water and salts to penetrate, and rust will begin to form and spread beneath the paint surface causing it to flake away. Suitable thermoplastic powder coatings can have longer durability than liquid paint in hostile environments. Plascoat PPA 571, a thermoplastic polyolefin powder developed by Plascoat Ltd, has demonstrated longevity in the North Sea. The photograph shows two safety railings on an offshore rig in the North Sea operated by a major Danish energy, offshore and shipping operations company. The railings were coated six years ago, one with liquid paint and the other with Plascoat PPA 571. The liquid paint has suffered consider- able deterioration, and corrosion of the underlying metal is evident. In contrast, the PPA 571 coating is intact and providing protection to the underlying metal.

For the offshore oil and gas industries, cost efficiencies have never been more critical. Oil and Gas UK reported that an urgent structural reduction in the industry’s operating costs was needed. Companies are now committed to reducing the costs of operating their existing assets, and a reduction of 22 per cent (£2.1bn) is expected by the end of 2016 (Source: Oil and Gas UK). In North Sea offshore facilities, one of the world’s toughest environments, wind speeds can reach over 100mph and waves are frequently 10m high. Metal structures and components face a constant challenge from corrosion and abrasion. In addition to salt spray, wind, ice and high UV, the drilling itself creates mud, acids and hydrocarbons. The useful properties of metal are degraded by corrosion: it loses its strength and its permeability to liquids and gases. Wear and tear, appearing as scratches, dents and pits, causes damage and also increases the likelihood of corrosion as water and salts accumulate in the pitted areas. This can eventually lead to premature, sometimes sudden, failure. The consequences of coating damage and corrosion are costly to the industry. Health and safety issues may arise from structural failure and the threat of hydrocarbon leaks. As rigs move into deeper waters, maintenance and replacement projects are becoming more difficult and costly.

Protection of the metal is the job of metal surface finishing, including galvanising,

PPA 571 vs liquid paint, on safety railings on an offshore rig in the North Sea

Plascoat Systems Ltd – UK sales@plascoat.com www.plascoat.com

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Tube Products International November 2016

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