Measuring Deformations with Laser Scanning – Storage Tank Surveys

August 22, 2019 Peter Merrett Laser Scanning, Technology

The main advantage of laser scanning when carrying out storage tank surveys is that it facilitates a comprehensive analysis of the tank in question. Instead of measuring a limited number of pre-defined points, the whole surface of the storage tank can be analysed. Scanning allows us to monitor the entire tank shell for deformation, as opposed to just surveying a limited number of discrete points.

Traditionally, storage tank surveys are carried out using a total station or a simple measuring tape. While these techniques provide the necessary position information, they are generally time intensive when multiple measurements are involved. When using a measuring tape, measurements are prone to errors. 3D laser scanning removes these deficiencies by capturing thousands of points in the same time it takes to capture ten points with a total station. Digital methods have transformed construction, and the application of laser scanning techniques in our storage tank surveys is not exception.

From the Data Captured Through Laser Scanning We Can Provide:

• Difference Maps that compare millions of points between scans to highlight areas where change has occurred.
• Radial displacement plots for every degree around the storage tank, and at different heights.
• Diametrical distance analysis, so that engineers can understand the variation in the verticality of the tank wall.
• Accurate strapping tables that not only incorporate accurate circumference and height measurements, but also all internal ‘deadwood’.
• Overall verticality analysis.
• Tilt/subsidence analysis.
• Peaking and banding analysis.

Preventing Future Issues With 3D Laser Scanning

We can also capture imagery on site with 3D laser scanning. This visual information provides a record of areas surveyed and could be used for monitoring or for Q/A of work carried out. The exact roundness of a tank is determined, this ensures that roof fabrication or seal selections match the existing structure. Alternatively, the information can be used to identify areas to be corrected for roundness and to verify repairs before fabrication.

Comparisons of millions of points between two scans over an extended period can highlight areas where change has occurred. Closer inspection or repairs could then be undertaken on the specific areas of concern to avoid costly failures and potential loss of assets.

Scanning a tank interior during an out-of-service inspection could provide the factual information needed to locate or to obtain measurements of: vapour control/fire prevention systems, roof supports, deadwood, valves and manholes. This information avoids the need to re-enter tanks to take measurements and can be beneficial in aiding any design projects. In our storage tank surveys, we use the very latest developments in laser scanning technology to provide the fastest and most accurate data possible.

Other Capabilities Of 3D Laser Scanners

In addition to tank inspection applications, 3D laser scanners can also be used for tank calibration and for the creation of accurate filling tables. In contrast to traditional methods of strapping or measuring with a total station, the technique involves placing the 3D scanner inside the tank – while out of service – to capture the tank interior. Data for both the tank floor or sump and filling volume are recorded in a single operation, and an estimation of tank thicknesses is not required as the internal cavity is directly measured.

Using laser scanning methods to survey the interior of a tank is also much faster than using traditional methods and is therefore safer. 3D modelling of the storage tank and it’s surroundings allows us to create a comprehensive data set. This data can be used to obtain direct measurements and volumes to ensure that containment dikes, for example, satisfy regulatory requirements. Areas of potential concern or failure can be quickly identified and quantified to reduce repair time.

In fact, the benefits of laser scanning methods stretch far beyond only our storage tank surveys. There are many wide reaching advantages of a laser scanning survey to the construction industry as a whole, so it is important to thoroughly research how one of these surveys can assist with your next project.

Accurate 3D Laser Scanning on Storage Tank Surveys

Our team not only apply their knowledge of the most effective 3D laser scanning methods when carrying out a storage tank survey, but do so across all of our services and for clients in any sector. Speak to us today about our laser scanning methods and contact us to discuss a project that requires our level of expertise.