Dredging discharge lines with high wear resistance and their incidence per m3 of the dredged material

We are all increasingly sensitive to the need for economic development compatible with environmental protection in managing our behaviour in relation to ecosystems.

Approximately 80% of world trade by volume and over 70% of world trade by value is transported by sea and managed from ports around the world. Countries are increasingly faced with the need to expand their land areas, and as many urban areas are located along the coasts and rivers, there is a need to maintain river transport routes. Vast lake areas rich in sediments (often polluted) need to be reclaimed and limitedly converted to the cultivation of plant species for human use.

In order to achieve this, it is essential to dredge the underwater seabed and remove the excavated material and recover it for social purposes. Specifically, the justifications that motivate the projects in the use of dredging are:

  • Increase the world trade
  • Population growth (urban development)
  • Climate change
  • Coastal protection
  • Energy demand

Discharge line components

As a key component in the transport process and therefore in the dredging cycle, pipes are exposed to often high levels of wear and tear and all pipes must be turned regularly during use to ensure that wear is uniform.

Depending on the environmental circumstances, a combination of different types of pipes is required for the discharge process. Steel pipes make the floating lines less flexible because they are rigid and reduce their effectiveness in rough seas, so these hoses must be interspersed with flexible rubber elements. Ball joints also provide a flexible load-bearing connection between the sections of an unloading line and their field of application is in use on floating lines. For several decades the dredging industry has had a low number of manufacturers and only a few suppliers.

This led to the development of high quality products that worked effectively and guaranteed longevity. Today the quality of pipes on the market is becoming dubious. The dredging pipe industry has seen great changes in recent years. Sometimes pipes are purchased according to customer specifications, which are neither technically appropriate nor rigorous. It is becoming easier for manufacturers to take advantage of the lack of standards and provide low cost, low quality solutions with a significant influx of low cost suppliers, using cheaper raw materials.

This lack of expertise has increased pipe breakage rates and shortened their working life. It is vital to ensure that materials are always of superior quality because degradation of properties is inevitable.

Recommended properties should be used as a guide to meet customer needs and raise the level of the industry.

KNN33_4.0  AR ®   Pipes & Floatssystem for Dredging

“The evolution of the progress of human civilization has always been stimulated by new materials”.

At every stage of human development, any kind of application has been elevated only by pursuing a relentless effort to develop and update materials. When a material seems to have given its best, looking for and finding the next generation of materials has always been the greatest concern and challenge for Kiasma Group scientists and engineers.

As a result of this relentless search for the best material, the KNN33_4.0  AR ® System (Thermoplastic Elastomeric TP-E) was born. The world has now entered the era of science and technology in which materials are now also managed at the nanoscale level, which has laid the foundation for new possibilities for the future of new generations of piping”. The lifetime of a dredging pipe depends on a number of factors: these include, first and foremost, the nature of the sediment it carries, application temperature, flow rate, flexibility, resilience, tearing at the passage of sharp solids, breaking load, elongation, yield strength.

Thermoplastic pipes when subjected to ambient thermal conditions above 30°C (86°F) lose a part of their mechanical characteristics such as pressure and tensile strength may exceed the yield strength threshold. Kiasma Group offers a three-layer pipeline in which the thermoplastic outer layer is white in color, able to considerably attenuate the effect of UV rays. The world of dredging has been waiting for more than 70 years for the market to be able to offer all these requirements in a single product: thanks to the R&D Department, Kiasma Group has succeeded in creating the KNN33_4.0  AR ® pipes & floats system.

The KNN33_4.0 ®   AR technology has also been tested on heavy construction sites with sediment passage from 60 to 220 mm and compressive strength up to 170 Mpa and compared with other types of pipes. Today with KNN_4.0  AR ® technology it is appropriate to consider the discharge lines for dredging no longer as a “Commodity” but as an “Asset” because according to their long working life (low wear, high resilience, low tear) they are able to transport many millions of m3 of sediment, considerably decreasing the incidence per m3 of the dredged solids.

The layer inside the pipe makes it suitable for the basic classification referring to the genesis and composition of the sediments, from the less heavy ones as fine-grained loose materials to the heavier ones as sedimentary rocks. KNN33_4.0  AR thermoplastic multilayer pipes have much less wear than steel, HDPE drinking water pipes, UHMWPE and rubber pipes.


Multilayer thermoplastic pipes KNN_4.0 ® AR type AR -1AR – 2AR


  • KNN_4.0 ®   AR Clay – Silt – Mad
  • KNN_ 4.0 ®   1AR Compact Silt – Plastic Mad – Sand – Fine gravel
  • KNN_4.0 ®   2AR Big Gravel – Shale – Schist – Sandstone – Granite Rock
  • For pipes diameter from 6”(160mm) up to 40”(1000mm) ; Operating pressure from 58 PSI(4 Bar) up to 290 PSI(20Bar).

With an outer shell made of thermoplastic HDPE PE100 – PE4710.

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