Front end planning fundamental to realising full cost benefits of off-site modular construction

Front end planning fundamental to realising full cost benefits of off-site modular construction

Modularisation has taken centre stage as a highly efficient, productive, cost effective and safe solution for constructing green and brown field plants worldwide. This strategy allows for the off-site construction of modules in open, non-hazardous environments, which are then transported as complete structures via ship and road to the final plant site.

With extensive global engineering capabilities, professional know-how and experience in the construction of modules, thyssenkrupp Uhde has delivered many successful modularisation solutions for a wide range of industries, from petrochemical to mining, around the world. The South African office was responsible for all engineering and design work as well as project management of modules that were required as part of the expansion/upgrade of two local refineries and a fertilizer plant. “Modularisation is suitable for virtually any industry and application. We are seeing more and more customers making real estate available to thyssenkrupp Uhde for off-site modular build,” notes Mira Krid, Manager Civil & Structural at thyssenkrupp Uhde.

However, in order to get the full cost benefits, Mira advises that it is critical that the customer’s decision to go modular is made at an early stage of the project, ideally at the front end during conceptual design. Proper front end investment, conducting of the essential cost and benefits analyses and scoping the most effective and affordable strategies will ensure far less escalation at the back end. “When one of our customers made a late decision to change from ‘stick built’ to modular, we were required to do great deal of engineering and design rework with subsequent cost implications.” Mira explains that structural engineering for modular construction requires more effort at the design stage compared to the design of a ‘stick built’ structure. “For example, lifting and transport methods have to be decided upfront so that factors such as dimensional restrictions, with input from transportation and rigging contractors, are taken into account during 3D modelling. So the fact that we could still show a cost benefit to the customer after adapting the ‘stick built’ to an off-site modular build illustrates thyssenkrupp’s competency as well as the tremendous value of modularisation.”

On-site construction can be hampered by physical and environmental restrictions resulting in costly delays, reduced productivity and increased risk to personnel safety. Space limitations can impede contractor access forcing on-site building to be done in phases; the structural team has to wait for civils before building structures to the point where they can supply a certificate of compliance to enable mechanical to start loading equipment. Environmental factors to consider can include anything from harmful emissions to extreme temperatures.

By contrast, the building of modules off-site in an open, easy-to-access area and in a non-hazardous environment facilitates efficient, productive and safe work. “We can, for example, build scaffolding around the module without restricting people working on the inside,” says Ranka Sofijanic, Manager Plant Layout and Piping at thyssenkrupp Uhde. “Civil, structural and mechanical teams can work in tandem, installing all disciplines in the module, leaving only a few functions such as interconnectivity work once the module has been lifted into its final on-site position. We have an interface file for each module showing us exactly where to build every grid and pipe point, cable end and rack, etc. that has to link to neighbouring modules or structures on the plant.” Leaving only minimal on site work, especially in a hazardous environment, is a massive advantage of off-site construction. Plant sites where there are deadly emissions or high noise levels, place personnel at extremely high risk. The essential wearing of Personal Protection Equipment restricts movement and slows down productivity. Flammable environments also pose a danger as welding sparks may ignite fuel/gas systems.

A good example of how modularisation can offer an ideal solution where temperature extremes make on-site construction virtually impossible is the successful off-site modular construction of a diamond mine in a sub-zero region in Canada. In addition to putting personnel in great danger, the icy conditions would have severely restricted outside work with subsequent costly delays. The answer was to construct the entire mining plant in modules off-site, in fact, in another country altogether. Once completed, the modules, some weighing up to 580t, were shipped to their final destination. As the off-site construction was completed in Saudi Arabia where temperatures exceed 50°C, a great deal of engineering was required to ensure optimum functionality at the final sub-zero site. Despite this, the efficiencies of modularisation still outweighed the transport logistics as well as the costs that on-site construction would have posed.

thyssenkrupp Uhde is perfectly positioned to provide customers with best-in-class modularisation solutions, drawing from its holistic in-house capabilities that include state-of-the-art, customised software programmes, laser scanning, 3D design, integrated engineering and checking tools and Quality Control. Ranka unpacks some of these competencies: “Our Integrated Piping Programme (IRP/ERM) system is designed for processing and controlling piping information from P&IDs to construction/commissioning and provides maximum quality assurance. We also use E3D which is a customised multi-user and multi-discipline 3D intelligent modelling design software package. Multi-disciplinary design is executed in-house in accordance with Standard Working Steps and Modularisation Design Method produced for a specific project.” The modules go through the full rigorous inspection and are Quality Controlled on the piece of real estate on which they are built.

These capabilities enable thyssenkrupp Uhde to construct modules, varying in size and complexity, from equipment skids and pipe rack modules to complete process buildings, on a significant scale to meet customers’ individual requirements. thyssenkrupp’s expertise also extends to skid-mounted modular solutions, the Tanzanian chlorine plant being a good example. The company is able to design fit-for-purpose modules that can be containerised in 20 or 40ft containers.  “We fully customise the modules so no two structures are alike; we build what the customer wants,” conclude Ranka and Mira.

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