Customer's Challenge

A semi-submersible Floating Production Unit (FPU) as illustrated in Figure 1 consists of 10 riser systems and designed to produce 100 000 barrel of oil per day (bpd) and 100 Million standard cubic feet per day (MMSCFD) of gas at Gulf of Mexico. The riser casings which are around 2m tall and wide, require stringent GD&T fitting which required precision machining to fulfil the design intent.

During fabrication stage, the riser casings were installed 4 meters above ground with large opening at the front as shown in Figure 2. After discussed with client to understand their main concern and identified the constraint from conventional metrology method, FARO Vantage laser Tracker was deployed for the assignment to achieve the precision measurement needed for the application.


The 5 areas of interest for each riser casing are:

  • Diameter of the Cone A/B/C and D
  • Centers of A/B/C and D
  • Taper Angle at A/B/C and D
  • Surface runout of Cone A/B/C and D
  • Surface runout of casing’s bottom plane

A “as it is” dimensional survey was conducted to gather each riser’s condition, analysed using Spatial Analyzer metrology software as shown in Figure 5. This capability enables our client to determine the datum for setting our portable boring machine and make sure there are enough material to achieve the required dimensions.

The FARO Vantage laser tracker was extensively leveraged for this project, using it to check the setup of portable boring machine as well as conduct multiple interim and final post machining surveys.


The digitalization of measurement data using FARO Vantage laser tracker enable fast analysis and simulation which help client in their decision making process and improved project efficiency. With the help from FARO Vantage laser tracker, each casing took around 4 days to complete pre survey, in-situ machining, interim and post machining survey.