Working water column

Haplast supplies ventilation pipes, ventilation basins and ventilation towers for large and small construction projects. Based on KRAHTM technology, we tailor our own pipe, bend and T-pipe for ventilation projects.

Ventilation in the ground

Ventilation and airflow requirements have increased significantly in recent years, and engineers have had a problem finding space for the large pipes needed to distribute the large volumes of air. Since the 1980s, we have been working on sealed solutions for ventilation ducts that can be buried in the ground. This has enabled large central energy rooms in, for example, schools and other buildings with several wings. In many cases, an entire floor can be saved because the main pipes are laid under the building. Today, we find that even the largest pipe diameters are used to bring out the large volumes of air required.

Ventilation tower

Air inlets and outlets can be moved out of the building as freestanding towers. Either designed as a single tower or as a double tower with pipe in pipe where the outlet is in the innermost pipe and the intake between the outer and innermost pipe. Pipes in polyethylene is a very poor heat conductor and heat loss is insignifcant. 


Pipe and parts are produced as a kit based on exact drawings from the client or consultant. They are supplied in black PE with a light-colored interior surface to facilitate inspection. PE-pipe is used in the ground and normal steel pipes take over above the floor.

The system consists of pipe and parts that are precisely adapted to an assembly plan. The pipes are produced with an internal diameter from 600 to 3000 mm. These can be delivered as ready-to-build modules from 6 to 24 meters, and the modules can be joined to achieve the required length or height according to drawings.


Our ventilation pipes have a calibrated machined pointed end and a sleeve with a molded rubber gasket. This jointing method ensures lasting tightness for the system. For large pipes, the pipes can also be joined with an extruder weld on site if a fully welded system is desired.

Low weight and long service life

KRAHTM pipes are strong, flexible and have a long service life. They can withstand the necessary loads and are highly suitable for ventilation pipes. The low weight simplifies storage and placement on the construction site.

Products we can deliver

Ventilation pipes

Intake and return towers

Combi tower / extra tower meter

Ventilation bend and T-pipe

Sleeve and tip with gasket

Ventilation transitions