Laser Scanning for Asset Management
Offshore assets should be routinely inspected to ensure their condition is accurately understood. Incomplete information about the condition of offshore assets constitutes a serious risk to offshore operations. The high precision measurements provided by underwater laser scanning provides the certainty needed to make informed decisions and ensure safe offshore operations with industry leading detail.
- For manufacturing spools or jumpers, obtaining accurate post-installation measurements of relative position and orientation differences between flanges or hubs of subsea structures is critical.
- If spools or jumpers are not designed within engineering tolerances, stress will be placed on connected flanges or hubs, causing subsea assets to be placed at risk.
Highest Efficiency Metrology Method
- Since the advent of wideband acoustics, LBL acoustic positioning has been the standard for subsea metrology, providing centimetre-level accuracy. The advent of Laser Scanning, in conjunction with an INS, has demonstrated millimetre level accuracy in record times using a Dynamic Scanning solution.
- This new method achieves accuracies robustly below metrology tolerances and in significantly less time than existing metrology methods resulting in substantial cost savings.
The New Standard: Dynamic Metrology
- The ULS-500 PRO can capture data without contact, on the fly, generating high-resolution 3D models.
- The data captured by the ULS-500 is well within the accuracy necessary for design and fabrication of spool pieces, making the dynamic method the new standard for accurate and efficient metrology operations.
Pipelines and Freespans
- Offshore pipes are built to withstand harsh conditions, but exposure to anchor drag, seismic activity, currents, corrosion, expansion, and contraction eventually take a toll
- When pipes become dented or buckled, their ovality becomes compromised, which inhibits fluid flow and causes revenue loss from reduced operational efficiency or pipe failure in extreme cases
Repair with Precision
- Once pipe damage has been located, closer inspection of the specific area of damage needs to be conducted. Using underwater laser scanning, highly detailed 3D models of pipe geometry and the surrounding seabed can be generated
- These 3D models provide the information needed to accurately understand the implications of the damage and effectively develop a plan for repairs so that operational efficiency and safety can be restored
- Underwater currents can remove large amounts of seabed material from beneath the pipeline, resulting in long sections of unsupported pipe, that can lead to bulkling. AUV’s integrated with a laser scanner can track and scan long sections of pipeline to check for freespans. Algorithms can be developed to automatically detect the top of the pipe, as well as the plane of the surrounding seabed to calculate whether a free span might be present
Assessing the Current State
- Obtaining accurate information of the deterioration and changes to tubes and jackets is essential to enabling effective project commissioning
- Additionally, understanding of the current state of tubes is important for maintaining the integrity of assets and projecting work necessary across their lifespan
Constraints of Caliper Pigging
- A traditional approach for interior tube inspections is caliper pigging and simple video inspection. However, caliper pigs for large diameter pipes are extremely heavy, which increases deployment complexity and project operating costs
- Also, spacing between each of the caliper pigs’ sensors means that the results will be low resolution and that the production of the final models must rely on data interpolation
Laser Scanning for Precise Results
- 2G Robotics’ laser scanners produce submillimeter resolution 3D models, removing the need for data interpolation by capturing detailed geometry and anomalies that traditional methods would not observe or, at best, poorly define
- Obtaining accurate as-built information is critical. As-built surveys of new or retrofited underwater installations provide essential information for project commissioning
- As-builts also provide detailed records of assets at the time of survey, which can be used as a baseline for future inspections
- When compared to traditional methods for generating as-built models, underwater laser scanning enables much greater detail with higher resolution, higher accuracy point clouds
- The resulting models are able to show millimeter level discrepancies between the as-built state and the initial design
As-Builts as an Added Benefit
- When underwater laser scanning is employed for a specific measurement, such as metrology, the entire structure can be scanned without adding any time or cost to the project
- This means that a model is generated, even when that was not the initial purpose of the campaign – ultimately providing useful as-built information in addition to the target measurements
- Mooring chains experience significant linkage wear in addition to deformations, elongation, and corrosion as a result of stress from wind, waves, currents, and tides.
- Compromised mooring chain integrity threatens the security of anchored offshore assets, so knowing the condition of mooring chain links is critical.
Limitations of Calipers
- Traditional subsea measurement techniques such as caliper methods, require the chain to be removed from operation and manually measure and therefore are unable to provide the level of accuracy or speed of inspection afforded by underwater laser scanner technology.
- In addition to capturing the specific measurements of interest, more complete link analysis can be performed with the full 3D model of the link that can be generated.
Accurate Chain Assessment
- The ULS-200 can be rigidly attached to the chain at a set distance and perform scans over multiple links. From these scans, accurate measurements of chain wear and elongation can be obtained.