Borcoat™ polypropylene coating provides innovative thermal insulation for deep water Gulf of Mexico project

Borealis has developed innovative Borcoat™ polypropylene (PP) materials that thermally insulate the flowlines and risers serving the deep water Thunder Horse Field. This project uses the world’s largest semi-submersible production platform operated by BP in the Gulf of Mexico.

Designed to carry up to 250,000 barrels per day, the Thunder Horse Field flowlines posed a major technical challenge. At subsea depths of 2,200 metres the flowlines are exposed to extreme external pressure and low temperatures. Combined with a flowing oil temperature of 132°C, this presented a huge thermal insulation challenge. In such deep water, normal foam insulation solutions are not feasible as the water pressure causes foam to collapse and lose its thermal properties.

The stringent requirements imposed on the thermal insulation system by deep water and high temperatures led Thermotite, a division of Bredero Shaw and a leading manufacturer of thermal insulation systems for offshore pipelines, to execute a rigorous development and qualification program capable of demonstrating the suitability of polypropylene based materials in these extreme environments. Through collaboration with Borealis, this qualification program concluded by selecting unique Borcoat materials.

According to Allan Boye Hansen, Technology Manager at Thermotite: “The multi-layer insulation concept based on Borcoat PP materials is a significant breakthrough with respect to material selection for insulation of high temperature, deep water flowlines and risers. Of particular value is that it gives a wide degree of flexibility which will allow modification to match the specific needs of similar projects in the future.”

The first of the 7-layer system is a fusion bonded epoxy primer, the remaining 6 layers are made up of a range of Borealis Borcoat products. The combination is new in its entirety and some grades have been specifically developed for the Thunder Horse application. To one of these new Borcoat products, Thermotite adds glass spheres during the extrusion process to create a syntactic polymer. The syntactic polymer layer acts as a thermal barrier and as thermal insulation on the risers. Also unique is the combination of two Borcoat grades that are mixed together with a blowing agent to create high strength foam, which further increases the flowlines’ insulation and resistance to extreme sea pressure. This combination of syntactic and blown foam is known as the Thermotite® 7-layer system.

Through the combination of existing and newly developed products, Borcoat enabled the design of the multi-layer solution to meet the necessary strength and stiffness requirements, as well as the stable thermal insulation performance during operation of the flowlines.