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

In the case of UV light cured CIPP products one can use unsaturated polyester (UP) or vinyl ester (VE) resins, depending on how aggressive substances are. The carrier can be fiber glass or fiber glass with felt.

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 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 stored in a dark place protected against UV rays. From the place of storage the pipe liner is delivered to the construction site in containers or boxes that ensure optimal transportation conditions.

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 sluice is attached through which a set of UV lamp carriages will be inserted, and a pressure hose is connected through which air is fed under pressure. This is to calibrate the position of the pipe liner inside the rehabilitated sewer. Once the pipe liner is calibrated, through the sluice a set of carriages with UV lamps is inserted into the pipe liner. The UV lamps emit light at an appropriate length. The curing process of the pipe liner results from UV light while the carriages with UV lamps are being drawn at a preset speed determined by the size of the rehabilitated sewer and thickness of 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 process installation parameters are recorder, like internal pressure, continuous log of carriage speed, temperature from pyrometers (air temperature in the front and back, lining temperature).

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.