Discharges to air and sea are inevitable during precommissioning and commissioning of long subsea pipelines. Large quantities of water is pumped through the pipeline during these operations. This water is normally treated with corrosion inhibiting chemicals to minimise internal corrosion of the pipeline. Chemicals like methanol or glycol may be used to prevent hydrate formation, and will normally be discharged to sea during commissioning. In order to minimise the environmental impact of these operations, while maintaining corrosion protection, the Norwegian Statoil has been working for several years along three main routes such as to develop concepts and methods that minimise the discharged volumes, the use of the most environmentally friendly chemicals available, and to monitor and identify the effects of discharges to various marine species. 3 refs., 4 figs.
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