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Grade R5 mooring chain:

performance on manufacture and tests

The R5 mooring chain supplied by AsAc has been applied on the CNOOC "CNOOC- 981" Project and has a high performance on sea wave resistance, sea water corrosion resistance, impact resistance, deformation resistance, fracture resistance and fatigue resistance. The rig has experienced a hurricane that occurred in the year 2000 with no damage.

Technical Characteristic of R5 mooring chain of AsAc

1.Good performance on mechanical properties

The results of mechanical tests meet the requirements of international standards, specifications of classification societies and are of an advanced level. The tensile strength is higher than 1000Mpa; average impact value of base and weld is more than 58J and 42J respectively; and the yield ratio is smaller than 0.92, which is an extremely hard research subject.

2.Advance manufacture technology

Compared with the materials of R4 mooring chain, the kinds of alloy elements and contents for R5 steel have been modified after a large number of experiments. The parameters of flash butt welding and heat treatment during manufacture are verified in practice and achieve an optimized result.

3.Multi additional tests

Besides the normal tests of R5 chains, a large number of additional tests have been carried out such as Crack Tips Opening Displacement test, heat treatment sensitivity test, strain age test, hot ductility test, slow strain rate test, fatigue test, environment induced crack test and structure analysis etc.

4.Strict requirements on test conditions and results

For SSRT, the required stress rate is 10-5/S, while the tests carried out by AsAc had rates of 10-6~10-7/S. The specified test environments are air and artificial seawater, but AsAc has taken additional tests at acid water to study the Hydrogen Embrittlement Resistance. For fatigue test, the cycle times have increased by 10%~20% to discover the fatigue performance of AsAc's R5 chain. After tests, there were no factures or any other defects observed. The results of these additional tests have met the requirements of international standards, specifications of classification societies and reached a world advanced level.

When the typhoons "Plum Blossom" hitting HYSY981,on August,2011, AsAc’s R5 mooring chain withstood the great test Keeping the platform safe.