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Notice 306563006  served against Shell U.K. Limited on 14/08/2015
Notice Type Improvement Notice
Description In 2014 Shell decided that it was necessary to connect the Station Keeping Assist Vessel (SKAV) “Pacific Dolphin” to the “Curlew” because of concerns about the integrity of the Curlew’s mooring lines. On 19 January 2015 the towline between the SKAV and the FPSO snagged the gas export pipeline’s subsea isolation valve skid and the SKAV crew applied increased tension to the towline until the pipeline ruptured and released its inventory of gas to the sea surface, thus exposing employees and others to a risk of fire and/or explosion. The management of change process failed to ensure that a suitable and sufficient assessment of the risks to the safety of their employees and other persons not in their employment was made. The Curlew Station keeping HAZID dated 3/12/14 failed to identify the specific risk from the towline snagging and then rupturing the gas export pipeline which is located on the seabed at a depth of 90 metres and with a gas inventory directly proportional to its 12 inch diameter, 125 bar operating pressure and 21 km length. The Activity Specific Operating Guidelines (ASOG) contained in the Curlew 2014/15 Station Keeping Assist Bridging Document failed to effectively take into consideration the measures recommended in the Station Keeping Assistance towing analysis (DNV GL Report No A11328), which specifies that in order to achieve the ASOG requirement of a minimum sea surface clearance of 25 metres at the mid-water arch, the tensions should not be less than 50 tonnes for a towline pay-out between 600 metres and 700 metres. This recommendation contradicted the ASOG condition ‘Towing line tension – 35 ton max load to be applied to the tow line. Further the ASOG condition relating to ‘loads applied to the tow line to manoeuvre Curlew’ derived from the tow line mooring analysis were not included in the ASOG. As a result of a change to use the Curlew emergency towing pennant instead of the bridal to connect the Curlew to the Pacific Dolphin, a technical drawing of the towing arrangement to aid the crew of the Pacific Dolphin was not issued to the vessel as part of their management of change process.
Compliance Date  30/10/2015 Revised Compliance Date 
Result  Complied with

Breaches involved in this Notice

Location of Offence 
Address Curlew/Shell U.K. Limited
Shell International Petroleum
Shell Centre
York Road
LONDON
SE1 7NA
Region
Local Authority Not Applicable
Industry Extractive and utility supply industries
Main Activity 06100 - EXTRACTION OF CRUDE PETROLEUM
Type of Location Floating Production System (FPS)
HSE Details
HSE Group HIDEDU1S1 HSE Directorate Hazardous Installations DIrectorate
HSE Area HSE Division