The SCORCH (Seawater Corrosion of Ropes & CHain) Joint Industry Project (JIP) was established by AMOG in response to an industry need for design guidance for addressing corrosion of chain and wire rope in tropical waters. Existing design guidance was more relevant to corrosion in cold waters, based on experience from the North Sea. A number of mooring line retrievals from tropical locations had demonstrated higher corrosion rates than allowed for in existing design guidance.
As part of SCORCH JIP, a large sample of retrievals (388 chain coupon and single link tests and 373 wire and wire rope test results from full scale operating mooring lines and a series of site and laboratory tests) have been investigated. After analysing all the data, working models of corrosion of mooring chain and wire rope in warmer waters have been produced and the results have derived significant advances in knowledge and recommendations for use with mooring design and through life operating practices.
The SCORCH JIP has proven to be a major success with companies involved in the JIP being able to predict corrosion rates and being provided with insights to avoid unplanned change outs of moorings and mooring failures due to corrosion.
With access to the full data base of retrieved chain and wire rope samples from over 20 locations around the world in similar locations to proposed and legacy moorings, SCORCH JIP members are able to better manage through life mooring inspection campaigns with regard to corrosion as well as avoiding the sizeable costs of unplanned mooring change outs and failures by understanding their corrosion liability.
The SCORCH JIP has identified that those facilities relying on current codes of practice will, in many circumstances be operating at risk of:
- Substantially under estimating the through life rate of corrosion
- Under estimating the risk of failure/premature retirement due to corrosion, and
- Unaware of the opportunity for early & safe rectification of their mooring system.
The SCORCH JIP has investigated and characterized mooring chain corrosion, both in terms of uniform corrosion and MIC related pitting corrosion. In tropical waters this corrosion was found to be on unprecedented scales not previously identified or accounted for in design guidance. The rate and extent to which these occur can now be predicted using results from the SCORCH JIP which is a major advancement for operators and designers of permanent mooring systems in cold, temperate and tropical waters.