For oil and gas companies

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1 Laser scanning with dimensional control Integrating traditional methodology with new scanning technologies to achieve higher order accuracies for critical interfaces and tie-in points PETER FIELD Warner Surveys For oil and gas companies operating in a volatile climate, careful planning and tight control over construction and maintenance programmes have never been so vital. The sheer immensity of most projects and the scale of investment involved places huge pressures on all parties from stakeholders and engineers to engineering procurement, construction & design (EPCD) contractors, with projects often scheduled for completion within extremely short timescales, working around the clock. Errors or misinterpretation during design and fabrication can easily occur, leading to the need to rework not just minor parts but substantial plant items. A key contributor to project over-runs, reworking can account for up to 15% of total budget costs on new build developments and a significant proportion of the cost for scheduled maintenance and engineering works. These are costs that could be totally removed by anticipating issues ahead of time through closer collaboration and employing survey techniques up front. Figure 1 Laser scanning provides a reliable method for surveying congested and often inaccessible areas of plant. However, hostile site conditions may affect accuracy, and dimensional control techniques may be required for critical tie-in points A huge leap forward for surveying, laser scanning enabled the remote capture and dissemination of large amounts of data, where previously each data point had to be measured individually and, frequently, physically. The technology is now used extensively for the accurate mapping of large scale developments and complex sites, including heavily congested or inaccessible areas with complicated assets in the hostile environments such as those to be found in refineries and industrial plants (see Figure 1). Collaborative working Being able to call on a comprehensive database offers benefits for collaborative working, where many different influ- PTQ Q

2 encers require input into the design process. The interoperability of modern 3D models created using a variety of software packages, central to the building information modelling (BIM) workflow approach just now emerging in construction, has been employed extensively by the oil and gas sector over many years. Providing a visual representation of plant structural and operational aspects, the digitisation of data in this way creates a central information resource that saves time and greatly reduces the risk of errors and need for reworking to ensure projects are delivered on time, on programme and on budget. Having a shared source of accurate data allows project engineers and contractors to maintain control over all aspects of the engineering and fabrication phases of oil construction projects, delivering improved returns through an integrated approach. Early intervention pays dividends It is often the case that survey services are first deployed on large projects at the point where fabricated elements built to original designs are brought to site to check. Reworking may be required where misalignment occurs, causing delays that could be avoided by surveying earlier in the process to approve the designs ahead of fabrication, allowing build issues to be detected and rectified before on-site construction commences. Design errors or omissions can lead to inadequate project specification, with estimates of cost accuracy being underestimated in some cases. The early involvement of surveyors at cold eyes review stage can help with assessing design concepts for constructability, providing access to site-experienced expert knowledge of the issues that can occur and potential workarounds to guide engineers and designers with less experience to this level of project complexity. Early screening and availability to survey data plus a fresh pair of eyes can offer new solutions to deliver cost savings and prevent project overruns, helping to secure an earlier return on investment. Shutdowns and turnarounds minimising your downtime Shutdowns are an inevitable feature of refining and can represent a significant proportion of a plant s yearly budget. Typically, these will be scheduled every 3-5 years, taking plants or part-sections offstream to undertake inspections required to comply with regulations and to carry out necessary repairs and maintenance. A percentage of these events will involve major plant replacement, with planned downtime periods offering the opportunity for scheduling in revamps and regeneration. Whilst shutdowns are usually planned when production is at its lowest, and such maintenance is important in maintaining productive capacity, extensive planning and control are required, often several years beforehand as well as during execution. Turnaround time is dependent on the extent of the project and any problems that occur. Any derailment of timetables for example where reworking is required, with much of the work difficult to scope in advance could result in the loss of millions of dollars for every day of lost production and incur additional direct costs for labour and heavy equipment usage. Key to the planning process is the availability of accurate legacy data for buildings and structures. The availability of a comprehensive database generated through laser scanning and the conversion of point cloud data into computer aided design (CAD) models provides a tool for asset management and a valuable guide for extensions and alterations, particularly in clash prevention, where pipes and new elements of plant must be integrated within already congested sites or structures. However, existing legacy data could be up to 15 years old in some cases, increasing the chances of misalignment or poor fit where plant elements are fabricated working to original designs. For this reason, it is advisable to consider commissioning additional laser scanning surveys to help plan the shutdown properly. Lack of detail could otherwise leave asset owners and contractors having to deal with considerable variations in scope during the execution of projects. Completion of design work in the point cloud or model environment in advance provides the necessary assurance that the process will be clash free. Unplanned shutdowns Unplanned shutdowns can have a significant effect on facilities and their operators. In addition to the production losses incurred during shutdown, unplanned events place huge pressure on resources 2 PTQ Q

3 when operations are restored, with capacity needing to be restored quickly. Outages of this kind can also affect the wider economy, with the lack of availability of fuel supplies creating a knock-on effect on industry and deliveries. Managing shutdowns and turnarounds successfully involves planning ahead to extend the period between shutdowns and eliminate unexpected downtime through preventative maintenance. Although survey companies including Warners will generally offer a rapid response service to cover emergencies, regular surveys to assess plant condition can avoid unexpected maintenance costs and business disruption, both of which may seriously impact on the bottom line. Laser scanning or dimensional control? The choice of survey type can sometimes be confusing for project teams, with laser scan surveys often requested when the required tolerances in fact necessitate dimensional control techniques with more traditional instrumentation. So how do you decide what you need? These definitions may help: Laser scanning is a rapid and reliable method for surveying often inaccessible, complex or congested areas. Survey control is the essential, traditional survey activity providing the auditable accuracy to so many survey operations including laser scanning. Dimensional control is the name given to high accuracy survey techniques used to achieve a Figure 2 Basic dimensional control techniques are used to ensure a single weld hook up (SWHU) for fabrication and installation of new modules good fit up between new, basic pieces of plant. Critical interface surveying raises the bar for dimensional control and relates to high accuracy techniques and instrumentation used to achieve first time fit-ups between new and old complex (often dimensionally corrupted) pieces of plant or structures. SWHU (single weld hook up): although basically with the same objective as critical interface surveying, this has become the term generally applied to very large projects with multiple modules requiring a first time fit with no additional spool connections (see Figure 2). Data accuracy Whilst fit for purpose for many design and construction applications, laser scanning is subject to inherent limits on accuracy, with terminal accuracy subject to and dependent on a number of variables. Good quality survey control, range, reflectivity of the surface, type of scanner, temperature variations, stability of the survey subject and even the symmetry of a survey subject can all have an impact on results. In the real world, most survey subjects are exposed to a significant temperature change, which alone can account for several millimetres difference in the data registered. Additionally, the noise produced within a point cloud from a flat surface can range from as little as 2mm to 10mm or more depending on the quality of scanning instrumentation and the surface being scanned. Interpolation of this noise can lead to further distortion in the data. Where the objects being scanned are vibrating or subject to other influences that can cause movement, this will also affect the results. For this reason, claims that laser scanning can provide accuracy to within +/-2mm should be approached with caution. Using the highest pos- PTQ Q

4 essary software in some cases. Often however there is no substitute for a full CAD model. Figure 3 Checking cone shapes for potential fit-up accuracy sible specification terrestrial laser scanner in a stable, controlled environment at relatively short range (10-20m) and with high order survey control (+/-1mm), it may be possible to produce data to that kind of auditable accuracy. If the data is not auditable, accuracy claims should be dramatically downgraded, with +/-5mm being more realistic. Moreover, the concept that modelled surfaces are more accurate than the basic cloud data is only true in certain circumstances. Surfaces are often irregular, the geometry of old basic primitive shapes becomes corrupted, and even the lack of dimensional integrity of basic primitives can result in some software squaring off or smoothing out such irregularities. Although they result in a very good looking model, they do not accurately represent what actually exists on site, so on this occasion the accuracy of the model can actually be dictated by the quality of the structure being surveyed. While a number of software companies are actively involved in investigating how these limitations can be overcome, a commercially viable solution is still some way off. Another option available to data users is to bypass the automated software corrections and more complex as-built geometries by interrogating the underlying databases directly. Frequently overlooked in the delivery of 3D models, the point cloud database captured by the laser scanning process offers a valuable resource for designers and contractors. Containing high quality, auditable data that can be interpreted factually, these databases offer the flexibility to interrogate and view point clouds to produce 2D plans and elevations directly. This allows the freedom to request additional deliverables from the original survey team in the form of sections or drill down into specific areas at a minimal extra cost. In addition, opening up wider access to raw data within project teams can facilitate greater interoperability, although this may be hampered by the availability of the nec- Dimensional control raising the bar For surveys of existing plant, where the key aim is to get a record of what is present, accuracies of 10-15mm, laser scanning and 3D modelling will be sufficient to prove the design is clash free. A more inclusive and wide ranging approach, critical interface surveying calls for a different order of complexity and accuracy in dimensional control. Essential in achieving a first time fit, this requires working to tolerances of 1mm or less (see Figure 3). Applications for this higher order accuracy include ensuring complex new fit-ups such as cone to cone connections between new and old plant are achieved on a first time lift and fit or high value reactor/regenerator heads and internal components are replaced in a single lift. Consistently achieving a weldable 3mm root gap actually requires surveying to a 1mm accuracy. Dimensional control is the key component of major plant replacement projects involving any major item of process plant whether cutting heads off reactors and regenerators or dimensionally controlling the fabrication and the installation of new PRT lines. Off-site fabrication In the quest for greater consistency and faster construction, prefabrication where assemblies are manufactured under factory conditions then transported to site for incorporation into project civil engineering works is 4 PTQ Q

5 increasingly common in revamp and new build projects. Offering greater programme certainty and lower labour costs, this approach also results in less waste. However, the in-situ work abutting prefabricated assemblies requires absolute accuracy to avoid civils interface problems and achieve single weld hook-up (SWHU) objectives. Warner Surveys applies high order total station survey control, combining laser scanning with proven methodologies such as conventional survey control, dimensional control and critical interface fit-ups and is active in the further development of traditional survey techniques for inspection and visualisation to include dronebased/unmanned aerial vehicle (UAV) and vehicle-mounted scanners. It is the combination of laser scanning, conventional survey control, dimensional control and critical interface surveying that can provide the overall database for design, BIM and clash prevention applications along with 1mm accuracy dimensional control techniques for specific corridors of interest or tie-in points. Other issues where surveys can help Tower installations This task requires tried and tested standard operating procedures including at least one visit to the fabrication environment, on-site surveys to the civils interface, pre-shimming and checks against design elevations to ensure not only a vertical installation but an installation that successfully interfaces with adjacent plant. Reverse engineering Continually vibrating and often hot existing plant can become dimensionally corrupted over time. Achieving a successful interface between new designs and old plant or pipework connections will therefore be problematic, especially where designs are based on old data. Planning ahead by testing the designs against actual plant condition prior to manufacturing will avoid delays on site and potential reworking. Ambient temperature correction enables matching of connections between the new plant and existing structures subject to temperature variations in operation. The availability of improved intelligence removes the risk of clashes and poor fit-ups. Visualisations Using survey data to build 3D animations can help avoid problems where large built-in cranes are operating in confined spaces. Providing a visual walk-through, these animations can track the trajectory of crane movements to ensure there will be sufficient clearance with no part of the crane or the load likely to hit surrounding plant, something that is very useful during constructability studies. Case study Warner Surveys was awarded an engineering project for Tengizchevroil Future Growth Project-Wellhead Pressure Manage-ment Project with survey teams based in Kazakhstan, Korea and Italy over a four-year period. The company is part of the team providing front-end engineering design (FEED) and engineering, procurement and construction management activities. The FEED stage is now complete and detailed engineering under way. Warner Surveys has been appointed to oversee all technical aspects throughout with the aim of ensuring first time fit on site (SWHU). While laser scanning models are being used to ensure clash prevention, process plant design and asset management, the technology will only be deployed during engineering and construction to provide final clearance checks prior to shipping through dimensionally restricted inland waterway systems. The extent of the project and the off-site fabrication of modules require the application of high-end dimensional control techniques throughout to ensure final correct positioning as per design, working within very tight tolerances of less than +/-2mm. Warner Surveys will be involved in the full life cycle of every module from fabrication and transportation to on-site positioning and the final hook up. Working closely with the local fabrication teams from its local office in Kazakhstan, the company is responsible for the establishment of standard operating procedures and validating the accuracy of the fabrication process through to sign-off. Constant monitoring and reporting allows any occurrences outside of accepted tolerances to be checked back with designs and the necessary amendments made before shipping to site. As part of this brief, Warner Surveys is involved with marking the cut lines for pipe connections. PTQ Q

6 On-site, the company will continue to manage the civils interface by setting out demarcation lines and match marks to allow cranes and other module transportation systems to manoeuvre and lower modules into place on the concrete foundations to achieve the delicate fit required. The result is a perfect SWHU, minimising construction timescales and avoiding costly on-site reworking. Pushing the boundaries Continued investment in research and development focuses on the assessment of different technologies and new instrumentation to find the best way to generate accurate data that is fit for purpose across a range of diverse applications. Often the subjects to be surveyed can be in aggressive or hostile environments, subject to extremes of temperature and may be hundreds of feet away: new solutions are emerging that can overcome these problems. For example, many chimneys and industrial plants are in distress. The use of UAVs for inspection removes any risks and can generate highly accurate inspection reports on movements or decay as well as dimensional change where deployed by survey specialists. Warner Surveys is also currently evaluating new products to measure movement quickly and efficiently, including Leica GeoSystems Kumonos system, which appears to provide a reliable method to map and report changes to cracks on structures remotely, thereby removing access issues and improving the health and safety aspects of a project. Used largely by construc- tion companies to date, 24/7 automated monitoring and reporting also offers potential benefits for oil and gas companies. Installed and set up in just a few days, the remote system provides real-time updates via dedicated websites on how plant is moving during operational cycles and whether it is performing safely and as per design expectations. Providing 3D movement monitoring and change reporting, the automated system issues s and/or text messages when pre-agreed key trigger values are exceeded, enabling timely action to be taken to prevent further deterioration, which might lead to major failures. Structured support Increasingly, suppliers are working with project teams and organisations on major longterm projects across a range of areas from construction site engineering surveys to multiple site and large site topographic surveys as well as international oil, gas and energy projects. Working within a framework agreement or on a call-off basis ensures the availability of support and expertise at every interface to deliver a seamless progression and offers an economic solution, fixing costs through the establishment of an agreed schedule of rates. With the necessary certification, stakeholders also benefit from the added assurance of compliance with safety standards. In addition, Warner Surveys has established a Quick Quote mechanism to simplify process management and communications by providing a fast turnround for urgent and additional survey requirements. It was also one of the first companies to set up an autonomous CAD department, a move designed to give designers and contractors increased flexibility and improved integration, with the reassurance of independent results. Built-in protection With the price of oil expected to remain low, oil and gas companies are increasingly concerned with how they can reduce costs on their capital projects and operations. There will always be uncertainty at this level of complexity, but taking a few basic steps can eliminate the risk of additional costs and minimise delays. Land surveyors have a duty of care to ensure the services provided are fit for purpose and delivered to the required accuracy. Equally however, designers and construction professionals need to be clear about what the project demands. Ultimately, good survey control techniques must lie behind and support the laser scan, however high its quality, providing auditable proof that there is no degradation in the laser scan due to other outside influences. A holistic approach to surveying, which combines laser scanning and modelling for project stages where lower accuracies are sufficient, along with the higher order accuracy of dimensional control for critical interfaces and tie-in points, will always deliver the best results. Peter Field is Managing Director of Warner Surveys Ltd and a fellow of the Chartered Institute of Civil Engineering Surveyors. 6 PTQ Q