For many non-circular pipes running below the ground across Australia, the reality of their renewal is imperfect.
If a pipe is perfectly circular then standards, specifications and renewal methods are well documented and accepted. The same can be said for pipes that have deformed to a uniform oval shape within a limited range.
However, as soon as a pipe’s internal shape deflects outside strict parameters, the most efficient and sustainable solutions have been more difficult to design – until now.
At Interflow, there is an innate drive to find world-class solutions to the most complex customer problems. A great deal of thought and research has been put into the effective use of Finite Element Analysis (FEA), a computer-based method that has been used in other engineering sectors, including aerospace and automotive, to understand the way complex objects behave under various types of loading conditions.
“Fundamentally, FEA is based on mechanics and mathematics,” says Dr Weigang Wang CP Eng, Design Manager at Interflow. “The computer does the calculation and gives us the very best solution.”
The method works by dividing a complex structure into many small, interconnected components, or ‘elements’. Engineers can then use computer simulations to evaluate how each element responds to applied loads, and how all the elements interact to represent the behaviour of the complete structure under different loading conditions.
In the 1970s, Boeing made extensive use of FEA during the development of the 747. Through FEA simulations, engineers were able to assess the aircraft’s structural integrity, predict stress distributions, and refine the design to enhance both safety and efficiency. In these virtual environments, designers can examine how each component responds to different loads and conditions. In the Boeing case, this means things like weight, aerodynamic forces, and material stresses. The digital model closely replicates real-world behaviour, allowing engineers to modify and test the design repeatedly until the structure performs as intended.
Once the configuration and material properties have been optimised through the simulation, the final design can be produced with confidence that it will meet performance and safety requirements.
“At Interflow, we see FEA as the next evolution in the design approach for complex pipeline rehabilitation,” says Ervin Hung, Interflow’s Strategic Solutions Operations Manager. “What transformed the safety and efficiency of aircraft and automotive industries can now redefine how we strengthen and renew pipeline infrastructures.”
“FEA delivers a new level of clarity, allowing us to see precisely how a structural liner of any shape responds to real-world loads and conditions. When we apply this to non-circular pipelines, we can design with greater efficiency, reduce material use, and ensure performance with measurable confidence for the asset owners.”
The FEA modelling process brings enormous value when it drives decisions in the field.
Take grouting or void filling of liners as an example, Hung says. “When grout is pumped into the void around a flexible liner, the intention is to fill that void. This can involve the build-up of a great amount of pressure. Over-pressuring the liner can deform it beyond design limits, or in the extreme case, burst the liner, which can have unintended environmental consequences.”
“When the lined pipe is circular, we know the exact forces it can withstand. However, when it is a non-circular shape, the risks are much higher. Using FEA, we can use the grout’s properties and model the buoyancy loads on the liner to generate the most efficient grouting methodology with no risk of overpressure.”
If an FEA model reveals a liner can be 20 per cent thinner for the same level of performance and efficiency, there is an automatic saving of material, fuel, handling effort and time throughout the entirety of the supply chain and installation process.
It can mean fewer people are underground or on site and are there for less time. This introduces a safety dividend and a community benefit.
When designers use FEA to quantify limits, field teams can be confident in their defined procedures. As a result, risk drops and less resources are required.
Interflow isn’t suggesting that FEA is used on every renewal project. The sweet spot for the technology, Wang says, is in complex edge cases, including non-circular sections, asymmetric deterioration, unusual load paths or where unique pressures, such as staged grouting, couple with structural response.
“In these instances, the traditional methods are not very accurate,” Wang says. “As a result, people might apply conservative inputs to be safe. This will cost more, will take longer, require more resources and from the construction point of view might create more challenges.”
“As we have been making use of this tool on real projects, we have found it produces a more sustainable design solution that carries less risk. It also delivers greater value for asset owners.”
The final challenge is a cultural one, ensuring project teams and customers know when to tap this expertise, particularly during bid and design as opposed to after methods have been locked in.
A centralised design centre of excellence, available to everyone at Interflow, helps to route complex projects through the right channels, improving visibility and sharpening knowledge around innovative tools such as FEA. “We’re involving our design and engineering team earlier in the process,” Hung says. “This early collaboration ensures right-sized, fit-for-purpose solutions become the norm for complex, non-circular renewals.”
