The manufacturing process of 750mm and 900mm corrugated plastic pipe requires the release of hot air from inside the corrugations in order to properly form. This hot air is allowed to escape from the corrugations during the extrusion process via vent tubes that run the length of the pipe.
Vent tubes become exposed when the pipe is cut in the field to install (a fitting, connect to a manhole) or otherwise adjust the length of a pipe run. Exposed vent tubes may result in a leak path, and therefore it is recommended that they are sealed.
It should be noted that internal cuts or exposed vent tubes are not structural concerns and the requirement to seal them depends on site conditions and project specifications. A variety of methods can be used to seal vent tubes. Below video showcases one method, spin welding.
Cutting and sealing vents on 750mm and 900mm corrugated pipes
