Clash detection and reporting with 3D Laser Scanning - Part 2

Modern ship building is a modular process, often large parts and components are fabricated in multiple ship yards. 3D laser scanning can be deployed to as-build such components at separate yards and visually bring them together to check for clashes. In part two of our Clash detection and Reporting with 3D Laser Scanning blog we discuss how we use the very latest advances in clash checking software and techniques to enable fast and efficient checks.

01 April 2016

Vessel construction and large component integration

Modern ship building is modular in its approach with large parts often fabricated in completely different ship yards. Often these parts are big and complex with cluttered interfaces. 3D laser scanning can be deployed to as-build such components at the separate yards and visually bring them together on a computer to check for clashes long before they arrive for assembly.

Intertek is using the very latest advances in clash checking software and techniques to enable fast and efficient checks in a matter of days. This has a number of advantages. Firstly, there are no surprises when the components arrive for integration. Design changes occur regularly during these projects, and the final fabricated component may have elements not included on the original design. Secondly, clashes may occur that are not immediately obvious. For instance, rotating interfaces may have elements that may clash during operation but are not noticed until operational checks begin. Intertek can bring 3D laser scans of such elements together and simulate the operational movement to check for clashes. Thirdly, these components are often lifted in by heavy duty floating cranes that are very expensive to operate. Knowing in advance that the parts smoothly fit together reduces installation time as well as potential standby time which would be necessary while clashes are removed. Finally, if a clash occurs when installing large components with floating cranes it is typically necessary for someone to  manually remove the clash (e.g. suspend under the load and cut out the class with a gas cutter). This represents an obvious safety issue which can be avoided by scanning the components ahead of time.

A good example of this is the Turret structure used in FPSO’s. The turret is a large rotating mechanism located at the front of the ship used to connect it to the gas field subsea structures.

Fig 3: FPSO

The turret component is often awarded to a fabrication yard that has previous experience in these specialised components. The remainder of the FPSO may be constructed in a yard in a completely different country and the turret then shipped to the vessel for integration at a later date.

Intertek has successfully performed clash checks under these circumstances by 3D laser scanning both the interfaces of the turret (on the FPSO in one country) as well as the turret itself (in a different country) and running clash check simulations.

Fig 4: 3D laser scanning the turret

Fig 5: Scanning the turret interface on the FPSO

Fig 6: Video showing clash checking of a turret

The very same processes can be used for topside module integration. There are often overhanging pipes or objects on the deck that clash when integrating topsides, and this can delay the process. Determining and removing these clashes prior to lifting the topsides module removes this uncertainty.

Fig 7: Massive floating cranes used for the installation of turrets and modules

Stuart has been working in precise surveying, laser scanning and metrology for over 10 years in Australia, SE Asia and Africa. He has started-up the Australian operations for Intertek increasing our global reach to this region. Intertek Surveying Services (formerly Hi-Cad) are a global leader in dimensional control and laser scanning.