Rehabilitation with a pipe liner cured in place (CIPP) – steam curing

In the case of steam cured CIPP products one can use unsaturated polyester (UP) or vinyl ester (VE) resins. As the resin carrier one can use a polymer unwoven fabric (PA, PAN, PET, PP) or, more often, ECR glass fiber. A combination of such fabrics can also be used. Membranes can be used depending on the requirements of individual producers of pipe liners.

TECHNICAL EVALUATION OF THE SEWER

Before the rehabilitation the pipeline is jet-cleaned with a sewer cleaning machine placed on a truck. After that the pipeline is inspected with a remote controlled camera. The analysis of the video from the sewer inspection forms the basis to create a detailed computer report on the technical condition of the pipe. On the basis of report data the sewer is classified depending on its technical condition.

SELECTING THE REHABILITATION METHOD

Depending on how the sewer is damaged or destroyed, as well as its classification to a specific group, an appropriate rehabilitation method is selected. After the evaluation of the sewer’s technical condition one should analyze geodetic data, groundwater level with respect to the base of the sewer, road traffic exposure, and other ratios that have influence on the selection of parameters of the liner that is to be used. On this basis an appropriate CIPP pipe can be selected at design phase. On the basis of the known Young (E) modulus, specific for the proposed carrier, the designer selects the thickness of the CIPP liner.

SATURATION OF THE PIPE LINER

Using negative pressure the pipe liner is saturated with resin in controlled conditions.

STORAGE AND TRANSPORTATION TO THE CONSTRUCTION SITE

The resin-saturated pipe liner is cold stored to which ensures that optimal temperature conditions are observed. From the place of storage the pipe liner is delivered to the construction site in containers or boxes which also ensure appropriate temperature for the specific resin.

Once the damaged section of sewer is taken out of service a slip sheet is pulled into it.

Having protected the surface of the host sewer, a winching machine is placed above the upstream manhole, a line is pulled to the downstream manhole, and there the liner is attached to its end. The pipe liner is pulled through at a controlled speed and pulling force.
After that, to a specially prepared end of the pipe liner a steam hose is connected through which air is fed under pressure to calibrate the position of the pipe liner inside the rehabilitated sewer. Once the pipe liner is calibrated, steam brought to appropriate pressure and temperature is fed into the pipe liner. This process is continued until the liner is cured, in accordance with internal guidelines and procedure that complies with ISO 9001.
After the installation, a milling cutter is used to cut off the ends in the upstream and downstream inspection chambers, as well as “blank” openings for connections in the cured pipe.
During the installation process several parameters are recorded, namely: pressure inside the pipe liner during all the stages of the installing and curing process, as well as continuous temperature and time readings from all control points throughout the curing process.

CCTV INSPECTION

Once the installation is finished and drains are opened a CCTV acceptance inspection is made and recorded on a DVD or another storage medium. At the same time an inspection report is prepared.

TESTS

In accordance with PN-EN ISO 11296-1, 11296-4 and PN-EN 1610.

Any defects are made good with the help of a camera-controlled robot and/or by patching with short sections of the pipe liner.