Optical Metrology Services (OMS) has successfully completed pipe measurement and fit-up analysis work for BAE Systems on the Woodside-operated Julimar Project, comprised the Julimar and Brunello natural gas fields.
In April 2015, Woodside acquired a 65% interest in the Julimar Project. The appointed offshore installation contractor, EMAS-Chiyoda Subsea, subsequently engaged BAE Systems Australia in August 2015 to carry out fabrication, testing, trial lift and loadout of 10-off subsea tie-in and jumper spools. This consisted of 18in 625 CRA-clad, 14in / 8in / 4in super duplex stainless-steel and 4in carbon steel materials before installation by the EMAS-Chiyoda Subsea construction vessel, ‘Lewek Constellation’.
Measure line pipe and bends
BAE Systems subsequently contracted OMS who travelled to BAE Systems Henderson fabrication yard, 45min south of Perth in Western Australia during November 2015 to measure the 18in and 14in line pipe and bends, and provide detailed ovality analysis for optimum material nesting to ensure compliance with the projects maximum HI/LO specification.
The project scope required OMS to measure 43in x 18in diameter CRA-lined carbon steel and 26in x 14in diameter super duplex stainless-steel pipe and bends, as well as 6in x 18in and 14in subsea connection hubs. The spools comprised a selection of straight pipes and bends to be assembled into prefabricated spool kits prior to subsea metrology data being available from offshore. These spool kits would then be constructed into the completed production spools once metrology data became available. It was necessary to leave certain pipes ‘overlength’ so that post-metrology cut-backs could be performed during final construction of the full spools. Induction bends typically feature a different shape to straight ends, presenting the team with some key considerations when selecting which pipes should fit-up to each bend within the spools.
It should also be noted that the internal diameter (ID), out-of-roundness (OOR) and shape of a pipe will often vary along its length, again presenting a challenge with the crucial fit-up and connection of the spool piece.
Bespoke pipe measurement for improved fit-up
The OMS Autotool was used to measure all pipes at the ends and along the body at specified locations to provide pipe geometry data. Measurements were taken at 20mm and 100mm from each pipe end, then every 200mm along the length of each pipe resulting in approximately 60 measurements per 12m pipe (which took between 30 and 40 minutes to measure). OMS then carried out SmartFit analysis of the pipes and bends, which resulted in the team having a complete insight as to how to achieve the best possible fit-up scenario, even if cut-backs proved necessary at the installation stage.
Pipes with the best theoretical fit-up geometry were then selected and cutback / seam orientations marked accordingly so that the correct seam rotation could be performed during fit-up to achieve lowest possible HiLo across all welds. OMS’ Pipe End Dimensioning service enabled BAE Systems to meet the project specifications set out by Woodside, as well as avoiding the use of pup pieces due to out of specification HiLo during a time critical post-metrology phase. As a result, BAE Systems can be confident that the fit-up is the best it can be and integrity has been maintained at such a critical section of the pipeline.
BAE Systems project manager Lee Gallagher said: "The BAE Systems team have completed all welding and fabrication, with the spools safely installed in the field. As a result of OMS involvement, all pipe fit-up’s on the project were perfect and well within project specifications."