THE WORK STAGES OF PIPE REHABILITATION USING IMPREGLINER
Optimum rehabilitation is carried out in several work stages. These individual stages are:
- Preparatory work for the rehabilitation
- TV camera inspection before inserting the liner
- Preparatory work before inserting the liner
- Installation of the iMPREGLiner
- Curing of the iMPREGLiner
- Work after curing the inliner
- Checking the sealing and job-site sample
- Final work
- TV camera inspection after the rehabilitation
PREPARATORY WORK FOR THE REHABILITATION
Safeguarding the job site
It is important the job site is sufficiently safeguarded before starting the rehabilitation. All necessary signage, diversions and barriers are to be put into place.
Barriers must be reported in advance to the appropriate authorities with sufficient notice.
Depending on the type of sewer and the size of the pipe to be rehabilitated, drainage capability must be guaranteed. During installation, it must be ensured that the section to be rehabilitated is not in operation. If necessary, corresponding shut-off bladders are to be put in place and the water must be diverted.
Shut-off bladders must be put into position with great care! The pressure that is created by the blocked water can cause life-threatening situations!
Milling work to the pipe
Obstructions such as the ingress of roots, foreign bodies, shards or joint packing, which prevent complete pipe cleaning or can lead to the liner being damaged when it is inserted are to be removed by suitable robots or manually.
Pipe offsets not only narrow the diameter of the pipe considerably; depending on the offset, the hydraulics can also be affected in such a way that increased deposits are to be expected, even with a low utilisation of capacity.
Laterals must always be measured precisely before installing the liner. This ensures that the laterals can be opened again without incorrect drilling after installation. It has been proven in practice that the same person closes the connections and opens them again.
The cleaning process is to be selected in such a way that further damage to the pipe is avoided. A high-pressure water and hydro-mechanical cleaning process is generally used to remove incrustations.
TV CAMERA INSPECTION BEFORE INSERTING THE LINER
The TV inspection is the last check of the pipe to be rehabilitated before the liner is installed. This TV inspection must be recorded in order to document that the sewer meets the necessary requirements for rehabilitation.
PREPARATORY WORK BEFORE INSERTING THE LINER
Insertion of the glide foil
After the TV inspection, a cable should be inserted into the pipe using the camera or the flushing equipment. This cable is used to pull the pulling cable and glide foil into the pipe. A swivel should be used to avoid the glide foil rotating during insertion. The position of the glide foil must be checked after insertion. The pull cable must be inserted in such a way that it is on the glide foil.
The glide foil must be fastened in the initial manhole under a shut-off bladder in the opposite manhole or on the floor with ground anchors. The foil serves as a glide foil and protective foil for the insertion of the iMPREGLiner into the damaged waste water pipe.
Attach the liner head
Before the liner can be inserted, a “pulling head” must be attached. The winch cable is then fastened to this liner head with a swivel. The liner is to be folded to half the width before being lowered into the manhole. The liner folded in this way is then handed to a worker in the manhole.
INSTALLATION OF THE IMPREGLINER
The insertion of the liner
The inliner should remain in the transport packaging for as long as possible in order to avoid unnecessary external influences. Please note that at low temperatures, the inner foil loses elasticity and the resin tends to stress-whiten.
The storage and working temperatures of 5 – 25 °C must not be exceeded or gone below. Please note the accompanying sheet. The liner temperature can be checked using an infra red measurement device.
A worker inserts the liner into the pipe and monitors the correct insertion. A winch and corresponding guide pulley are used to insert the inliner continuously into the pipe to be rehabilitated.
To reduce the insertion forces, it is useful to apply a biodegradable oil on the glide foil before insertion.
In doing so, the insertion speed must never exceed 5 m/min. Furthermore, the dimension-dependent maximum insertion forces must not be exceeded.
Insertion with the winch is continued until the pull head has reached approximately 30 – 40 cm in the downstream manhole. The end of the liner is lowered into the manhole using a cable depending on the depth of the manhole.
If the liner has reached its final position, the insertion is ended and the steel cable and the guide pulleys can be removed.
At the end manhole, the liner is then cut in such a way that approximately 0.5 m of the pipe still protrudes into the manhole.
Assembly of the safety caps
Safety caps must be assembled at the start of the liner, the end of the liner and in the area of any intermediate manholes that may be present. The safety caps ensure that the liner does not ever extend and burst in areas where it is not supported by the inner wall of the pipe.
Fitting the packer
The packer is now fitted at the initial manhole and at least two tension belts are fastened. The curing cable can now be moved into the liner. To do this, the packer is connected to the compressor and compressed air is applied.
At the end manhole, the liner must be pressed in such a way that it slowly lines up. The curing cable is to be replaced with the iMPREG Kevlar thread.
In doing so, it must be ensured that the cable is straight and not pulled around a corner. Otherwise there is the danger that the Kevlar thread might cut the inner foil.
Putting the UV light source into place
The light source, which depends on the nominal diameter, is now fastened to the curing cable and lowered into the manhole.
Compressed air is used to make the liner abut slightly again, so that it is possible to move the chain in without damaging the inner foil.
The chain must be moved into the liner with great care. Care must be taken to ensure that the wheels or parts of the chain do not damage the inner foil.
Once the UV light source has been moved in, it is also possible to fit the packer in the end manhole.
The packers are fitted in the initial manhole and end manhole and connected to the compressed air line. The yellow outer foil is to be cut at the initial manhole and at the end manhole, or completely cut off in dry pipes.
In the intermediate manholes, a transverse cut approximately 5 – 10 cm longer is to be made in the outer foil of the liner, so that the air that was enclosed when the packer was fitted can escape.
Setting up the liner
Setting up with compressed air must be carried out in several stages. The liner is slowly positioned, step-by-step, with 0.02 bar/min until the working pressure has been reached. It has been proven that 3 – 5 short pauses of approximately 5 minutes should be made in this working stage.
The working pressure is to be kept even during the complete curing phase!
Pulling the UV light source through with camera monitoring
Once the working pressure has been reached, this is to be kept for approximately ten minutes, in order to ensure that the liner does not get damaged when the UV light source is dragged through. During this process, it is possible to start pulling the light source, which has not been switched off yet, into the initial manhole. In doing so, the liner must always be monitored using the camera. This pull through must also be recorded with a video recording.
CURING OF THE IMPREGLINER
After the visual inspection, it is possible to start curing by switching on the UV lights and then pulling the light source through towards the destination manhole. In doing so, the switch-on times, which depend on the nominal diameter, the speeds and the lighting times in the installation manual must be noted.
Furthermore, during the complete curing phase, the speed and temperatures measured by the temperature sensors must be continually checked and logged.
Once the light source has arrived at the end packer, the lamps are to be switched off as per the table. The curing of the iMPREGLiner is thus ended.
The complete positioning and curing phase must be documented!
Removal of the packer and cutting off the liner
The packers are removed after careful cooling of the liner (approximately ten minutes). The liner is cut off at the ends of the pipe using an air grinder. This area must subsequently be connected to the old pipe with a suitable system.
Removal of the inner foil
The inner foil must be removed from the pipe area once it has been cut off. To do this, a cable should be connected to the end of the inner foil at the downstream manhole. The inner foil is then pulled out by pulling the cable at the downstream manhole.
LEAKAGE TEST AND JOB-SITE SAMPLE
The leakage test for each pipe serves as an interim check of the cured liner before the laterals are opened. The appropriate test pressure, pressure loss and test time must be checked in accordance with EN 1610.
The representative test piece is the reference of your own performance carrying out the work and the company’s calling card.
1. Taking off the pure resin layers and the outer fleece material, the wall thickness of the connection should be checked.
2. The surface of the test piece must not exhibit any pores, folds or cavities.
3. Sufficient UV rays / curing of the area removed must be ensured!
4. The sample must not exhibit any obvious issues in the laminate.
The samples are generally removed from the manhole area. If there is no representative sample available in the manhole, a sample piece must be taken from the pipe. In this case, the client must be informed in advance.
Restoration of the laterals
Compressed air or hydraulically-operated milling robots are used with camera surveillance to restore the laterals. Once the original measuring points in the manhole have been set up for the new pipe ends, the user can start the milling work from the control and monitoring vehicle.
Rehabilitation of laterals
If necessary, the laterals must also be rehabilitated through suitable processes such as top-hat profile technology or injection procedures.
Connection of the liner end
The liner can be connected to the old pipe using different systems. Systems for waterproof design of the connection areas:
- Connection of the pipe liner using an epoxy resin spatula
- Connection of the pipe liner using resin-based mortar
- GRP laminate
- Pressing with PU or EP resins
- Installation of a pipe liner end collar
- TV camera inspection after the rehabilitation
- TV acceptance inspection
Once the work has been completed, the pipe is flushed and the rehabilitated section of the pipe is then to be inspected visually. The TV inspection is the proof of properly executed rehabilitation. Furthermore, corresponding markings can be made at the start and end manholes:
- iMPREGLiner / UV curing
- Pipe markings
- Nominal diameter and wall thickness of the inliner
- Date of installation
- Documentation and checking
Please check your equipment before each installation to ensure that it works properly and is safe. Furthermore, you should carry out a visual inspection of the liner we have supplied before installation and check the accompanying datasheet carefully. If nominal diameter, pipe length and wall thickness are correct, the liner can be installed. Furthermore, the TV inspection should be recorded before and after the installation.
The following parameters must be recorded during the installation:
– insertion forces
– set up pressures
– working pressures
– temperatures measured by the sensors
– pulling speed of the UV light source
Checks of the job-site samples in the laboratory:
– short-term elastic modulus and short-term bending strengths
– wall thickness
– water tightness
In principle, a retained sample (job-site sample) is to be archived for the duration of the guarantee period.