Pipeline technology specialist STATS Group has completed its first subsea isolation project in China on a 780km pipeline supplying gas to Hong Kong.
Aberdeenshire-based company was contracted by COOEC Subsea Technology to provide a temporary isolation of the Yacheng pipeline in the South China Sea.
The pipeline had been damaged by a ship’s anchor and left unpiggable at a location about 280km from shore and in water depths of 90 metres.
The multi-million-pound contract included detailed engineering studies and comprehensive risk assessments which determined the best repair solution was to remove the severely dented section of pipeline and two pipeline end manifolds from the seabed on to a pipelay vessel, while the pipeline remained pressurised.
STATS Group, Dale Millward, director of EPRS and Subsea Services, said: “Since this pipeline is of crucial importance for the supply of gas to Hong Kong, the shutdown period for the repair work needed to be kept to a minimum. Therefore, the repair had to be done without depressurising and flooding the entire pipeline.
“To ensure safe recovery of both ends of the pipeline onto the pipelay vessel without depressurising or allowing water ingress into the pipeline, STATS Tecno Plug and BISEP isolation tools were installed. This enabled only the sections of pipeline that were being recovered from the seabed to be isolated.”
“The pipeline was repaired as safely and quickly as possible, without depressurising or flooding the entire pipeline and while ensuring that any seawater that may have entered the system was removed before the pipeline resumed operation,” Millward added.