Midwater Arch Downsizing

Decommissioning Case Study

Recycling Rate:
Ithaca Energy (sub-contracted to Global Energy)
Athena, Central North Sea
Nigg Energy Park, Tain, Highlands
Midwater Arch degassing and downsizing
Project Summary

The decommissioning programme for the Athena field saw the Mid Water Arch (MWA) – which had supported pipelines and control systems as they rose from the seabed – brought onshore for deconstruction and recycling. The 500Te structure was landed at the Nigg Energy Park.

Constructed of steel and measuring approx. 17m long, 15m wide and 7m in height, the MWA comprised an outer shell-like structure that wrapped around two pressurised buoyancy cylinders. The cylinders required degassing before the structure was downsized into road transportable sections. This work was undertaken on the quayside by our expert decom team at Nigg.

Due to its size, the structure was cut up manually using oxy-propane hot-cutting equipment. Mobile
elevated working platforms provided a stable elevated platform for our team to safely access the structure’s higher reaches. A crane held each section in place during cutting operations.

The cut sections were transported by our fleet of specialist trucks to our licensed waste metal
treatment facility at Evanton for full processing to ESSS standard, before being exported to European steel mills for recycling into new steel products, delivering significant environmental benefits.

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We are the largest metal recycler and exporter of processed metal in North and North-East Scotland and an experienced member of the decommissioning supply chain. With current strategically located licensed facilities in Aberdeen, Shetland, Evanton and Montrose, and the addition of our new quayside facility in Dundee opening in 2020 bringing our combined annual licensed tonnage to 360,000 tonnes, we are your decommissioning partner of choice.