Both in Africa and Europe, I have noticed many people birding these days, Frankly, for me, Birding can get a touch predictable. Sure, the sweet songs of warblers and the vibrant colours of hummingbirds are delightful. Coming from Sub-Saharan African Savannahs, we were less exposed to two more common Northern Hemisphere pitch black birds found on every Church steeple or city fence. Personally, I prefer a touch of these enigmatic Corvidae, the raven and the crow. These black harbingers of change have perched themselves in myth and folklore for centuries, symbolizing everything from wisdom to transformation. As we delve deeper into the world of trenchless pipe rehabilitation, a similar sense of revelation unfolds.
Just like watching a raven soaring through the sky or scaling a rickety crow’s nest affords a breathtaking panoramic view, understanding the intricacies of FFRP (Flexible Fabric Reinforced Pipe) and CIPP (Cured-in-Place Pipe) grants us a much wider understanding of pipeline rehabilitation. We are no longer limited to a narrow perspective. Instead, “just as these birds fly,” we can explore the most efficient and effective solutions for the rehabilitation of our underground infrastructure.
Much like the crow, a highly manoeuvrable bird known for navigating tight spaces, some types of CIPP can excel in tackling complex pipeline geometries. The resin-saturated liner, resembling the crow’s compact body and flexible wings, can in certain applications 90-degree bends with exceptional agility. This makes CIPP ideal for certain situations where the existing pipeline negotiates sharp changes in alignment, similar to a crow navigating a complex network of branches. Additionally, CIPP’s ability to access a pipeline from a single point to cure in place is much like a crow accessing shiny treasures in tight spaces with military precision.
The raven, with its impressive wingspan and ability to soar for long time periods, mirrors the core strengths of FFRP. This method utilizes a long continuous, flexible liner with embedded fabric reinforcements, as the raven’s broad wings allow it to soar for long distances, the strength allows for significantly longer pulling distances, often exceeding a kilometre in one go, thus minimizing the need for additional access points. However, FFRP’s inherent tough bursting and temperature resistance composition limits its ability to handle sharp bends. While it can navigate 45-degree bends, complex 90-degree manoeuvres or tight spaces are better suited for CIPP’s agility. In situations where there are longer sweeping bends with radii exceeding five times the pipeline diameter exist, FFRP’s extended reach is achieved, similar to how a raven’s powerful wings allow for efficient soaring.
Regardless of the CIPP or FFRP choice, achieving a close-fit liner allows for cost-effective material options offering longevity and operating capabilities withstanding internal and external forces and protecting the host pipe from corrosion. This approach enhances the inherent strength of the existing host pipe, allowing it to contribute to the overall structural integrity of the rehabilitated system. The host pipe can then assist in handling internal bursting pressures and external loads, thus maximizing the effectiveness of the rehabilitation process.
This philosophy underlies our core approach at ASOE. On demand liner solutions can be manufactured from nominal diameters of 50mm to 1400mm if requested to match the exact inside diameter of the host pipe. This unique ability to tailor the looms and extrusion process embraces the individual requirements of each pipeline, thus overcoming the outdated “one-size-fits-all” mentality. In today’s world of adaptability, the “one size fits all approach” limits budgets and trenchless design capabilities. This is why ISO 11295 below gives the interactive Class C specification for FFRP allowing the liner to interact with the host pipe as one entity connected by pressure.
This is not to say that there are not situations where in design, an annulus gap is accounted for. This is where ASOE uses Kevlar (Aramid) in the lining manufacturing process.
As ASOE’s vision and core values centre around the environment and cost effectiveness, we strive wherever possible to use less Kevlar. Hence, the use of more cost-effective Polymer yarns are used in the manufacturing of linings for lower pressures and temperatures found on municipal pressure pipelines. However, ASOE does use Aramid as all the ASOE oil, gas, high temperature, and pressure liners require this material for these applications.
FFRP has previously struggled with T connections, especially when air release, scour or other valves need to be installed. With a tight close fit liner, the ability to install a T connection once the lining has been placed will now become possible as the final stages of fine tuning and testing this technology are taking place. Asset owners will soon be able to place connections for smaller pipes or valves to T off the main FFRP. With an annulus gap connecting a T piece is not possible.
UT is a key non-destructive testing (NDT) method relying on sound waves. Dissimilar materials in liners and pipes, along with air gaps ( annuli), weaken these waves.
Water filling the gap certainly offers a slight improvement, but inconsistencies and complex wave interactions make this unreliable. A close fit lining, regardless of being CIPP or FFRP, ensures, if possible, a better, direct sound path for possible flaw detection through the liner and the host pipe.
This is particularly important for smart pigging, a common oil and gas practice. Pigs are cleaning and inspection tools propelled through pipelines. A close fit lining allows for efficient pigging, enabling comprehensive NDT inspections. Unlike municipal utilities, where internal inspections are less advanced and more focused on CCTV coding, pigging’s prevalence in oil and gas pipelines demands higher resolution inspections making a close fit system essential for reliable NDT.
Through a combination of visual inspections, understanding the host pipelines’ environmental conditions, advanced surveying techniques, and the material testing has been done, engineers can pinpoint the exact nature and extent of the pipeline deterioration. This allows for a more nuanced approach to rehabilitation. For instance, if the primary concern is internal leaks and joint failures on these assets with limited access, FFRP’s ability to handle high pressures and long lengths then ASOE becomes the ideal solution, similar to how a raven’s larger wingspan is perfectly suited for extended soaring. Conversely, pipes with multiple sharp bends, severe structural weaknesses, vacuum conditions or where external loadings exist, one would benefit from CIPP’s capabilities, mirroring the Crow’s resilient and efficient manoeuvrability.
In many cases, the optimal solution may be a combination of both CIPP and FFRP, just as the skies can accommodate both the raven and the crow. CIPP can be employed for targeted reinforcement in sections with sharp bends or complex geometries, while FFRP can address internal leaks and extend the rehabilitation throughout the remaining, straighter sections of the pipeline. This hybrid approach maximizes the benefits of each technology, delivering a cost-effective and structurally sound rehabilitation solution, ensuring the effective and efficient operation for your underground infrastructure.
It was this combination of technologies that resulted in ASOE receiving the (SASTT) Trenchless Technology award of Excellence during Covid in 2020 when both CIPP and FFRP were combined on a single project navigating 8 bends on a DN500mm pressure pipe system. The partners in the US on the other side of the pond have also had huge success with ASOE under the brand “Bullet Liner” where both CIPP patching and FFRP were used successfully on pressurised sewer and potable water mains.
For more information on CIPP or FFRP please contact us