Machining of Hang off Module (HOM) Rails on Deep Blue Vessel

The Challenge:
During pipelay operations the Deep Blue utilises a Hang Off Module (HOM) which is capable of clamping onto pipelines to allow end terminations to be installed before final deployment. The rails that the HOM runs on had become extremely worn and were affecting operations. The pair of rails, 11,080 mm long x 230mm wide, needed to be machined flat and to a common plane within 0.25mm.

The machining had to be completed within a scheduled maintenance period and therefore had to be completed in as short a timescale as possible

Our Solution:
To ensure the flatness tolerance was achieved over an area of 11m x 10m, the machining needed to be carried out with the minimum number of set ups. Our 6m milling beam was selected and our laser tracker was used to set the machining equipment, to complete the machining with 4 set ups. All equipment was shipped from Glasgow to Mobile Alabama, and two teams were mobilised to run the job 24/7

The Result:
The rails were successfully machined to the required tolerance and a full dimensional survey provided