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

In the case of hot water cured CIPP products one can use unsaturated polyester (UP), vinyl ester (VE), depending on how aggressive substances are, or epoxy (EP) resins. Usually, the carrier is made of polymer unwoven fabric (PA, PAN, PET, PP). 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, and 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 factors that have influence on the selection of parameters of the used liner that is to be used, and on the basis of the above select an appropriate CIPP pipe during the 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.

TRANSPORTATION TO THE CONSTRUCTION SITE

The resin-saturated pipe liner is delivered to the construction site in containers or boxes that ensure optimal temperature conditions for the specific resin. There is no need to transport pipe liners saturated with epoxy resin (EP) as saturating equipment is located directly next to the construction site.

Once the damaged section of sewer is taken out of service a protective sleeve (preliner) is pulled into it.
Having protected the surface of the host sewer a standpipe or inversion drum is placed above the place where the pipe liner will be inserted. The pipe liner is inserted into the sewer using the water inversion method.
Once the above has been completed the heating unit is turned on and heats water in closed circulation inside the pipe liner up to curing temperature.
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 of the liquid pumped into the pipe liner during all the stages of the process and curing, as well as continuous temperature readings from all control points during the curing process.

CCTV INSPECTION

Once the installation is finished and house 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.