Mooring chain inspections

Measuring chain dimensions is critical for verifying chain corrosion and wear rate design assumptions and confirming that chains maintain minimum strength requirements throughout their lifetime.

Available globally, Welaptega’s Chain Measurement System (CMS) is an optical caliper measurement technology that is used for measuring mooring chain dimensions and viewing material condition of links. The tool is positioned on a link to capture video data which provides a record of the inspection. The data is then processed to produce measurements of intergrip diameters and link length.

How does the CMS work?

The CMS is made up of four high-resolution video cameras (depth rated for 3000m), integrated LED lighting control and a topside digital recording system.

The video feeds from the tool is fed topside where specialized software selects the chain link apices and provides accurate, repeatable, and reliable chain measurements.

What can it measure?
  • Intergrip (grip zone) bar stock diameter x2 for every link measured
  • Link length for every chain link measured
  • Mooring line angle measurement
What are the benefits of using CMS vs. mechanical calipers?
  • Accuracy: CMS is accurate to less than +/- 1mm
  • Deployment time: the CMS tool has no moving parts and simply sits flush against the chain to collect data. This means there is no time wasted trying to “fit” the tool onto the link. Also, moving from one measurement site to the next only requires the ROV to slide the tool down or up the chain.
  • Specifically designed to be capable of being deployed in high-heave environments: most recent 2018 high-heave chain measurement campaigns: Voyageur Spirit (North Sea), Erha (West Africa)
  • Three measurements at once: the CMS collects two intergrip (double diameter) measurements and one link length measurement from a single placement of the tool
  • Correct intergip measurement location: specialized software ensures measurements are taken at the apex of the chain crown thereby providing the most meaningful and reliable measurement data.
  • Close visual record: CMS uses an optical system to collect measurement data, so CMS will collect high quality images and video of the measurement locations in addition to the actual dimensions.