LyondellBasell Industries has launched a new polypropylene (PP) compound that addresses customer needs in the rapidly-expanding market for flexible pipeline systems used in off-shore, deep-sea oil exploration. The new Hifax EBS 153D NAT product was developed for use in multi-layer syntactic coating structures for flexible risers and flowlines in order to create high-impact strength, improved flexibility and good compression strength in semi-flexible pipeline coating applications.
Higher flexibility while maintaining PP compression strength
Compared to standard PP compounds used in syntactic pipe coating, Hifax EBS 153D NAT features unmatched softness, an essential advantage for flexible off-shore pipeline utilities. "LyondellBasell's new grade addresses growing market needs, as flexible pipes are becoming the preferred solution in oil exploration," said Sean Comerford, LyondellBasell's Technical Service Manager for Pipe Coating. "Today's installation techniques require extensive bending of the pipes, and customers are requesting highly flexible coatings provided by products such as Hifax EBS 153D. The PP materials traditionally used for syntactic layers are more rigid; a semi-elastomeric coating layer based on Hifax resin enables customers to reduce the risk of stress and breakage in the coating during pipeline winding and installation. It also eases exploitation because the energy dissipation of the total pipeline system improves when exposed to seadrift."
Thermal insulation with good softness
The new resin also meets the demanding requirements of new polypropylene coating structures designed to provide high thermal insulation and high heat resistance. Off-shore pipelines laid in deep water environments present new and more demanding operating requirements for pipe materials. For example, deep water lines are exposed to extreme cold water temperatures on the exterior of the pipeline, while oil temperatures inside the line exceed 130°C. Coating systems must therefore ensure not only anti-corrosion protection, but sufficient insulation properties to avoid increased viscosity of the crude oil during transport from the seabed to the oil platforms and floating vessels. Added Comerford, "The products being transported from the ground through these pipelines are very hot, typically 90°C or higher. Maintaining the temperature coming out of the ground is critical to preventing the product from solidifying."
Coating pipelines at greater depths presents additional challenges. Coating layers must provide resistance to high compression as well as shear stresses that the pipe sections are subjected to during laying operations. According to Comerford, "The new Hifax EBS 153D NAT features typical PP properties such as high impact resistance, in combination with improved flexibility and softness."
Customers have reported that the new Hifax EBS 153D NAT compound is very cost-efficient. "By providing comparable properties, customers have discovered that a softer PP compound can be more cost-effective to use than other more costly flexible engineering materials that are combined at the application stage," said Didier Nozahic, LyondellBasell's Business Manager for Pipe Coating. "To achieve success in designs with stringent requirements, coating companies need simplified coating structures with reduced components.".