The first industry guideline on how to assess external mechanical damage to large fibre ropes has recently been completed and is today being presented at the Offshore Technology Conference in Houston, USA. The guideline has been produced on behalf of the oil industry and is suited to serve as an international standard.

DNV carried out full-rope damage testing before the new guideline was developed.

The guideline is a result of a joint industry project carried out in close cooperation with the rope-making industry, headed by Det Norske Veritas (DNV), and supported by ten international oil companies. Prior to this project, no industry standard existed for assessing damage to large rope of the types used in deep-water mooring.

The oil industry and rope manufacturers now have some experience in using fibre ropes for platform moorings in deep water. Fibre-rope mooring technology has been in use off Brazil since the mid 1990s, and several pioneering projects have now been completed in the Gulf of Mexico.

The new guideline is applicable to offshore-mooring fibre ropes that have been subjected to mechanical damage. It provides a method for quantifying the effect of findings from an inspection of a damaged rope on the further service ability of that rope.

For the industry, it is important to balance safety and cost, and to ensure that appropriate, well-founded action is taken at all times. The new guideline may enable the continued use of a damaged mooring rope, which earlier would have had to be replaced due to lack of knowledge about its condition.

In the project that was concluded with this guideline, extensive full-rope damage testing was carried out by DNV: Tests were performed on rope components with various degrees of damage, and verification tests were then performed on rope specimens that were identical to real service ropes.

The testing and development programme proved that the guideline was robust and versatile. The guideline is suitable to serve as an international standard since it is not limited to specific makes of rope or subrope construction.
The sponsors for the joint industry project have been: BP, ChevronTexaco, ConocoPhillips, ExxonMobil, Marathon, Norsk Hydro, Petrobras, Shell and Statoil. In addition, the following fibre rope manufactures have participated in the project: Bexco Ropes, Marlow Ropes, Quintas & Quintas, Scan Rope and Whitehill Manufacturing.

At the end of the project confidentiality period, which expires in early 2005, a Recommended Practice will be issued by DNV.