Offshore mooring rope specialist, Lankhorst Ropes was awarded a contract by NOV Flexibles, Denmark, to supply Lankoforce riser tethers for the Knarr field development, located in 410m of water in the North Tampen region of the Norwegian Sector of the Northern North Sea. The riser tethers will be the first to use Dyneema DM 20, a high modulus polyethylene (HMPE) rope, for permanent subsea anchoring of flexible risers.
Lankoforce riser tethers are designed to hold risers and umbilicals in position, connected to subsea production systems such as well manifolds, wellheads, Christmas trees and well jumpers. Each of the Knarr development riser tethers comprises two HMPE tethers connecting a hold-down clamp with an anchor, allowing rotation around two axes.
The riser tether has a Lankoforce rope construction with a 12 strand braided rope core made from Dyneema DM20. The high modulus polyethylene core provides the strength and mechanical performance expected of these long-term tethers. The entire rope core is protected by a braided polyester jacket and polyurethane coating, and includes ROV handling points for ease of installation.