Krah Asia’s  high density polyethylene structured wall pipes have the particularity of achieving high annular and longitudinal rigidity with very low weight. This is achieved by combining: – The helical arrangement of the ribs, which give it longitudinal rigidity.

– The design of a structural profile sized according to the stresses of annular rigidity of the conduction, achieving efficiency and avoiding the oversizing of the pipes.
– The low specific weight characteristic of high-density polyethylene compared to other materials is shown below.

Elastic pipes can react to changes in their environment. Due to the deformation performance, the load is distributed to its surrounding and the force acting on the pipe will be diminished. Within a short time there is a balance in the area around the pipeline and the deformation comes to a standstill. Plastic pipes react very flexible to static loads, while the loads do not concentrate themselves on the pipe, but are diverted to the surrounding soil. Flexible pipes still function, when other rigid pipe systems are already broken. Even in the case of a deformation the system is still absolutely resistant against infiltration and exfiltration. Since the pipes are profiled on the outside, these profiles can fix the pipes in the soil. There will be no or very few axial extensions in the pipeline. Krah pipes are nearly unaffected by temperature variations.

Inner diameter and hydraulic properties of Krah pipes will remain constant regardless of the wall thickness or the profiles due to the smooth anti – adhesive inner pipe surface. The nominal diameter (e.g. DN/ID 500) corresponds to the respective inner diameter according to DIN 16961. Compared to other pipe materials like concrete, smaller diameters can be used, which means that costs for material and installation can be reduced considerably.

The high impact resistance, even at low temperatures, ensures a robust pipe, resistant against impacts during transport, installation on the site and during the whole service life conditions.

For buried pipelines the biogenous sulfuric acid corrosion plays a key role regarding the longevity of the system. The biogenous sulfuric acid corrosion

only takes place above the water level and therefore only occurs in partly – filled pipes. Thanks to the used material, Krah pipeline systems guarantee optimum security and resistance.

The smooth round surface of plastic pipes does not give the teeth of rodents sufficient hold to cause damage. Moreover even in termite-affected countries no damage to polyethylene pipelines by termites has ever been documented. Polyethylene and Polypropylene are not a nutrient medium for bacteria, fungi and spores, so that the material is resistant to all forms of microbial attacks as well as to both sulfurous acid and sulfates.

Polyethylene and polypropylene pipes are among the most abrasion – proof pipes. This has been tested in the so-called Darmstadt procedure and the results are shown in the below diagram and confirm the quality of polyethylene pipes. Tests have been performed at the ”Süddeutsche Kunststoffzentrum” for its approval.

Black polyethylene pipes are permanently resistant to atmospheric corrosion and UV radiation. Due to that the pipes can be used and stored outside without the pipe material being damaged. No aging effect will occur.

Pipes made of Polyethylene and Polypropylene have considerable advantages to other pipe materials like concrete, steel, ductile etc. Due to their material the Krah pipes possess over a high elongation at break. This signifies that the pipe can support even loads or deformations, that were not included in the actual calculation and design of the pipe, like earthquakes. The Krah pipes deform to conform with the movement of the earth without any breaks or cracks, so that the activity of the pipeline is not drastically affected. As soon as the overload and earth movement ends, the pipe will go back to its initial condition and position. Another advantage is the high flexibility. Even in areas which are highly affected by earthquakes, our pipes are hardly damaged in comparison to pipes made of other materials. Despite the flexibility of the

Krah pipes they have a great capacity to carry loads, so that they are also suitable for road construction.

The deflection of flexible pipes is controlled by the settlement of the soil. After settlement, traffic and other loads do not affect pipe deflection. When pipes are relatively more rigid than the soil, the traffic and other loads have to be resisted by the pipe. Many years of practical experience have shown that flexible pipes (b) can resist traffic and other loads more effective than flexural resistant pipes (a) made of concrete or other rigid material. As shown in the drawing, the flexible pipes elude a selective strain by deflection. By this means the surrounding soil absorbs this strain

The service life of the complete Krah high-density polyethylene pipe system for gravity and low pressure applications is estimated to be 100 years, including a margin of safety. Each component is designed for a 50-year full and constant load case.

Krah pipes use of polyolethylene, have additional safety.

In the diagram you can see that the pipes are designed for a use of 100 years (a), including a calculated safety margin, stability (b) is achieved with constant load.