Quality Proves Its Worth

With the consistent application of Spiral-Wound technology for circular as well as custom-shaped profiles along several kilometers and for several years, Budapest has developed into a model city for Spiral-Wound pipe rehabilitation in Europe. 

The Spiral-Wound technology from SEKISUI SPR is already a familiar rehabilitation solution for the city of Budapest. Since 2010, approx. 18,861 m lengths of round as well as custom shaped profiles have been rehabilitated in Hungary and thereof 5,869 m beneath the Budapest city centre. With the latest large profile rehabilitation, the Spiral-Wound pipe system showed again its potential by rehabilitating 565 m of the egg-shaped sewer with dimensions of 1400 x 2100 mm. The trenchless rehabilitation was carried out together with the construction partner Agriapipe in the north-east of Budapest in summer of 2014.


The combined wastewater sewer, which has been in operation since 1907, exhibits material fatigue due to non-stop operation over the years as well as cracks and damage due to corrosion. The egg-shaped sewer in need of rehabilitation is located under the very busy main road, Pozsonyi Street, in the 13th district of downtown Budapest. For rehabilitation through standard manholes, only a few meters around the access needed to be blocked off for the equipment and the rehabilitation vehicle. There was hardly any hindrance for traffic above ground even though the rehabilitation project underground was rather large and many metres in length.


The 565 metre long sewer section was rehabilitated with the SPR™ Spiral-Wound method by winding a steel-reinforced profile strip of PVC-U into a new watertight liner directly within the host pipe. Once one of the 52 Spiral-Wound pipe spools was used up, the new profile strip was joined in a portable butt welding unit.

The winding process was carried out during controlled live flow in the old sewer. The goal was to maintain a water level of maximum 15 cm. Heavy rainfall posed a challenge occasionally as the water level rose to 1 metre and the winding process had to be interrupted briefly. Since the winding machine always remained stationed in the old sewer, winding could resume promptly after the water level had dropped and the pipe was cleaned.


The statically defined annular space of 50 mm to 80 mm between the Spiral-Wound liner and the host pipe was filled with a high-strength grout to re-establish the static features. The SPR™ Spiral-Wound pipe liner serves as formwork for a new mineral grouting of the old sewer and as a reliable protective coating over many years that separates the concrete structure from the combined wastewater. The smooth and abrasion-resistant surface of the SPR™ liner will improve the hydraulic capacity and compensates for the minimal cross-section reduction of the host pipe.