Numéro : 2715 - Year : 2017
Reliability of a concrete barge - Case of the N'Kossa barge
Pascal COLLET, TOTAL SA, E&P/DSO/IP/TEC/STR (Paris - France)
N’Kossa barge is the first and unique concrete floating hull in off shore Oil&Gas industry - 220 m x 46 m x 16 m, displacement 107,000 t including 73,000 t for the hull and 34,000 t for the topsides - this proceeding address the philosophy followed by TOTAL to assess the reliability of the concrete hull.
After 20 years Congo off shore, TOTAL E&P Congo intends to develop and operate for another 20 years or more new assets connected to NKP process/utility plant. Initial hull design was done with a projected 30 years service life and the Operator faces now the issue of assessing the hull soundness and reliability for another 20 years.
Reliability of concrete barge is linked to hull integrity all along the life of the asset. Other aspects such as mooring, motion in wave, fire and blast response are also a part of barge reliability but not addressed in this paper.
A Risk Based Analysis was performed taking into account prestressed concrete behavior with all concrete issues and loss of prestressing strength, fatigue effects, material ageing in marine environment and potential accident such as boat impact, chemical leak or fire and blast, in order to assess the potential failure modes and the associated symptoms. Based on the results, monitoring is implementing to provide a hull assessment tool to extend hull useful service life.
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