Around 100 km from Stockholm you will find Västeras, a large city at Lake Mälaren, the third biggest lake in Sweden. Västeras is a big industrial city that was founded over 1000 years ago. In the past year they had some trouble with leakages in the sewer system. High rainfalls had led to full pipes which resulted in an overflow into Lake Mälaren.

Sewage collection tank during installation

Krah Pipes Manhole

Therefore a quick, durable and reliable solution was needed. The engineering company Mälar Energie AB contacted Krah pipes yet again in January 2017 to plan the project for a 950 m³ sewage collection tank of DN/ID 1600 mm with a DN/ID 2000mm manhole. The first pipes were shipped already in October 2017, the project was finished in March this year. The manhole is equipped with a flow regulator 150 l/s from Mosbaek A/S. The incoming flow to the manhole is 350 l/s if the incoming pipe is working with full capacity. The pipes were delivered in lengths of 6 Meter including rubber gasket. In a whole, 41 trucks were needed to deliver the whole amount to the construction site.

Skyline of Jakarta

1. Basis

The development respectively the renovation of waste water ischarge system is always associated with high investments and extensive civil engineering works. Beside the purchase costs for the pipelines itself, also high proportionate costs arise for the grounds works and the pipe installation. 

Especially in topographical flat Asian metropolitan areas like Jakarta, the pipelines can often only be installed with a low longitudinal slope. Thus, the hydraulic capacity of the pipelines is decisively limited. Increasing the longitudinal slope again means expensive, extensive, technically sophisticated excavation works. In Asia, most sewage and drainage systems are made out of concrete. Those pipes have a very rough pipe wall and have a lot of connections, due to their production process and quality. By using suitable pipe materials that guarantee smooth walls and need much less pipe connections, the longitudinal slope can be reduced while maintaining the dimension and the hydraulic capacity. Thus, also the costs for excavation and civil works can be reduced considerably. Smooth walls also optimize the discharge conditions and especially avoid depositions during dry weather flow.

2. Dimensioning of the pipeline

Rublevskaya water treatment station has been operating since pre-revolution times and still remains the main source of potable water for Moscow, Russia’s largest metropolis. Today there are plenty of new materials and technologies available for water supply and water disposal which can extend pipeline operating life by up to 50 years or more. Implementation is going slowly, which is why the number of worn networks is still significant. The Rublevskaya water treatment station is no exception. Having reached a certain stage of operation, it needed restoration of its filtrate ducts – underground water mains of rectangular and circular cross-sections made of reinforced concrete. Specialists at Mosvodokanal confirmed the option to use circular cross-section plastic pipes in these conduits and ID 1400 mm and 2000 mm were approved for the various sections. They had to choose pipes and fittings for operating pressures up to 0.15 MPa, and find solutions for the following non-standard tasks:

• Installation of pipes, fittings and branching from inside, because opening of water conduits was only planned at places with bends and in chambers;
• Connection of the new pipeline to the old one;
• Pressure testing of the new pipeline conducted as for a pressure pipeline.

CORSYS PLUS pipes (pressure version) met all the requirements. These pipes fully comply with GOST R 54475 (used for the production of non-pressure pipes). In addition, they also go through an in-house pressure test similar to GOST 18599-2001 for at least 100 hours at a temperature of 20°C. This allows the use of CORSYS PLUS pipes for pressure systems with operating pressures up to 0.6 MPa. The reliability of the CORSYS PLUS pipes connections is ensured by electrofusion using special electric heaters integrated into the sockets of the pipes. This is the only type of connection that meets the requirements for a new pipeline.

Underground water conduit to be reconstructed

Welding of CORSYS PLUS DN/ID 2000 mm from inside using two welding units

Krah Pipes re-used as Flower Containment System

In today’s world recycling gets more and more important, as we have become aware of the fact that we only have this one planet and do need to be careful with it. But recycling is not always the best solution, sometimes a simple "down-grade" is enough as well.

Mall visitors enjoy the green idyll

Reasonable use of Krah Pipes