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Common Quality Problems Of In-situ Solidification Method For Trenchless Pipeline Repair

December 13, 2022

Any kind of trenchless construction technology, if there is no standard to regulate, or if the construction is not in accordance with the standard, quality problems may occur. Although we are vigorously promoting CIPP repair technology, we cannot take potential quality problems lightly. Recognizing the possible problems in this method will help us to further improve the technology and improve the process. The CIPP construction method often has the following quality problems in actual projects.
1. Pinholes and gaps
After the lining pipe is turned over and heated and solidified, water flow outside the pipe seeps into the pipe during use. The possible reason is that the impermeable membrane of the hose is damaged, or the hose is damaged during transportation or construction.
For this form of damage, there is little effect if there is no visible leakage. However, if the leakage is obvious, remedial measures need to be taken. If it is a partial leakage, local lining repair technology can be used; if there is a large area of leakage, it needs to be completely repaired; in large-diameter sewage pipes, artificial perfusion rings can also be used. Oxygen Resin Method Remedy.
2. Wrinkle
Two types of wrinkles, axial and circumferential, may appear in CIPP repair projects. The main causes of axial wrinkles may be inaccurate measurement of the original pipe diameter, excessive diameter of the lining pipe, or inconsistent inner diameter of the original pipe. Circumferential wrinkling may be caused by insufficient pressure during the turnaround, or by inconsistencies in the diameter of the old pipe within the repaired section.
3. Foaming
During the construction process, if the curing temperature is too high or the bonding between the impermeable membrane and the fabric is not firm, blistering may occur. Foaming makes the lining pipe easy to be worn, which seriously reduces the service life of the lining pipe.
4. Weak zone
If the construction process is not well controlled, or the construction environment is not suitable, it may lead to incomplete curing of the lining pipe, resulting in a weak zone. The heating temperature is too low, the heating curing time is too short, or the temperature of the groundwater outside the pipe is low, etc., which may affect the sufficient curing of the hose, so that the structural strength of the lining pipe cannot meet the requirements. Projects in this situation should be judged as unqualified and should be repaired again. If there is only a weak zone locally, the part can be excised and then repaired locally.
5. Uplift
Improper cleaning of debris in the pipeline, or misalignment and damage of the pipeline may lead to bulging of the lining pipe. These bumps can obstruct the passage of fluids.
6. Vitiligo
If the braided hose is not saturated with resin or polyester, these unsaturated areas will leave some white spots on the inner wall of the liner after curing. These white spots do not meet the requirements and need to be partially removed and repaired. If there are more white spots on the entire pipe section, it is required to remove them all and repair them again.
7. Liner pipe cracking
The reason for the cracking may be that the cooling rate is too fast and the lining pipe shrinks. Once the lining pipe cracks, it should be judged as a substandard project, and it needs to be repaired locally or the whole section.
8. Separation of lined pipe from old pipe
The reasons for this problem include insufficient air pressure or water pressure during overturning and curing, severe damage to the old pipe, and smaller diameter of the lining pipe than the inner diameter of the old pipe. In addition to the fact that the liner pipe falls off due to the severe rupture of the old pipe, it is unavoidable, and other situations should be avoided.
In addition to the potential problems described above, other problems may arise during CIPP pipeline rehabilitation projects. In order to ensure the quality of CIPP repaired lining pipes, we need to do a good job in professional quality inspection and evaluation to improve repair quality and work efficiency.

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