Scanners don't live in vain

Safety is Transco's top priority. On average, the company spends more than £600million a year in updating and maintaining safety on the UK's gas distribution network. Part of the funding is spent on educating employees and contractors about the potential hazards that exist on gas process plant.

In search of a better method for communicating the extent and severity of hazards, Transco teamed up with Multi-Tech Contracts, a Widnes-based company with a process industry background and experience of deploying 3D visualisation techniques to help interpret engineering information.

The Transco/Multi-Tech team chose to employ 3D and interactive media to model hazardous areas and zones based on an assessment of the frequency of the occurrence and duration of an explosive gas atmosphere. The results have brought tangible safety management benefits at no extra cost and helped to raise safety awareness amongst employees and sub-contractors.

In order to quickly and accurately model each Transco site, Multi-Tech and partner company Zoller and Frohlich (Z+F) established a plan to scan each site using Z+F laser scanning technology and then to use the 3D points for visualisation and direct measurement. Additionally the points would be reverse engineered into a 3D solid CAD model using the Z+F Light Form Modeller (LFM) software before visualisation by Multi-Tech in Navisworks.

Because there were a lot of sites to survey in detail, it was imperative to use a survey method that captured a lot of detail accurately and quickly. The Z+F scanner had several notable attributes that particularly suited it to this type of work, namely its very high speed of data capture and high data resolution.

The scanner's 360 degree field of view also made it an ideal choice for site coverage and productivity. Even large pressure reduction stations and gas-holder sites could be scanned completely in one day. Smaller PRS sites were completed in half a day and the smallest sites only required a couple of hours to acquire the necessary data.

Although speed of data capture is not everything for this type of engineering task, it certainly provided the team with increased flexibility within the survey process. Of paramount importance to the quality of delivery was the resolution of the acquired data and the ability of the survey team to perform a quality control check on the acquired data before leaving the surveyed site.

It was very important to determine and measure the impulse pipework of half an inch and below because these are used in engineering calculations. This required the laser-scanned cloud of points to be at high resolution. The Z+F scanner's data capture speed of 500 000 points per second enabled a sub-millimetre resolution to be obtained at 10m distance, while still only requiring three minutes per scan.

The ability to visualise each scan on site, immediately following a three minute cycle, proved very useful for checking the quality of captured data. The Z+F data was used in high quality grey-scale, akin to a very high quality black and white photograph. If data had insufficient quality for measurement or modelling purposes, software coding produced bright colours within the display. With many surveys data can only be checked away from site, meaning a costly return visit if there are any errors.

In parallel with the scanning, the Multi-Tech/Z+F team worked on the survey data saved onto CD and reverse engineered the data to 3D models. These models were geometrically assembled from the scanned data using the Z+F LFM software in conjunction with engineering input and 3D tools used by Multi-Tech. By working closely together in this way the team was able to find the quickest and most cost-effective method of assembling 3D models, with appropriate hazardous area classification being clearly visible in the form of 'balloons'. This 3D presentation clearly offers a much improved deliverable over the usual 2D drawings.

To assist with modelling, each site was 'brought to life' through panoramic digital photographs run on Multi-Tech software. A digital 3D walkthrough of each site was produced using real image footage taken during site surveys. The interactive photo-graphic record was produced by Multi-Tech's virtual reality imaging system, Multi-Pix VR.

Transco's North West Sector maintenance manager, Mark Williams, comments: 'The great benefit from using this system is that all the information can be viewed from a laptop. This enables maintenance personnel to look at the 3D model depicting the hazardous area zones. This can be of particular significance to the E&I staff when deciding where to site instruments and the type necessary. Also site modifications can be viewed and planned remotely using the panoramic pictures of the site.'

Glenn Halton is business development manager for Multi-Tech Contracts.