The main methods of repair are:
1. "U" type lining HDPE pipe repair technology"U" type lining HDPE pipe repair technology is also commonly known as the tight lining method, which includes cold rolling method, hot drawing method and deformation method. It is the use of HDPE pipes with an outer diameter slightly smaller than the inner diameter of the old pipeline, through the deformation equipment to press the HDPE pipe into a "U" shape and temporarily reduce the diameter, through the traction machine to penetrate the HDPE pipe into the old pipeline, and then open it with water or gas (steam) pressure and a soft body ball to open it and restore it to the original diameter, so that the HDPE pipe is attached to the inner wall of the old pipeline, and closely cooperate with the old pipeline to form a "pipe in pipe" composite structure that combines the anti-corrosion performance of the HDPE pipe with the mechanical properties of the original pipeline. During the use of the pipe after repair, the liner will eventually adhere to the inner wall of the original pipe due to the pressure of the medium within the pipe. This kind of repair technology is generally used to repair straight and circular pipelines with no serious structural damage, and can be applied to all kinds of pipelines with a pipe diameter range of 75 2000mm and a pipeline length of about 1000m. Because of its advantages of good hygienic performance, small loss of overflow section, large range of deformation and long-distance repair, it has been widely used in water supply and drainage and other related pipe network repair work. Moreover, China has begun to try HDPE pipe reducer repair, and has achieved remarkable results.
2. Soft lining methodThe soft lining method, also known as the in-situ curing method or the on-site molding and lining repair method, is currently the most popular trenchless pipeline repair construction method. It is a thin layer of tube that is tightly bonded to the old tube by lining the inner wall of an existing old tube with a layer of liquid thermosetting resin, which is cured by heating (using hot water, hot steam, ultraviolet light, etc.). The main components of the hose are: flexible fiber-reinforced hose or braid, thermosetting resin, catalyst. The most commonly used is braided tape, but there are also braided tubes reinforced with glass fiber, and the inner and outer surfaces of the tube are impregnated with a non-permeable coating to protect the resin in the tube. The function of the soft liner is to carry the resin until it is in place and cured, and there are two common construction methods used in the soft liner method.
One is the flip impregnated resin hose lining method, which uses a braided hose impregnated with thermosetting resin or a fiber-reinforced hose with impermeable membrane as the lining material, flips one end of the resin-impregnated hose and fixes it at the inlet of the pipe to be repaired with a clamp, and then uses water or air pressure to flip the inner layer of the soft liner impregnated with resin to the outside and bond with the inner wall of the old pipe. Once the soft liner has reached the end point, hot water or steam is injected into the pipe to solidify the resin, forming a hard liner with anti-corrosion and anti-seepage functions that adheres to the inner wall of the old pipe.
The second is the twisted hose lining method, during construction, the twisted wire rope is passed through the old pipe, the resin-impregnated liner is connected to the free end of the wire rope, and then pulled into the old pipe to be repaired. Finally, the wire rope is removed, the ends are blocked, and the liner is expanded with hot gas, hot water, or steam, and the resin cures faster. The loss of the overflow section of the pipeline repaired by the soft lining method is negligible, but the flow performance is greatly improved. The use of this technology can repair cast iron pipes, steel pipes and concrete pipes and other materials of underground pipelines, especially suitable for urban traffic congestion, ground facilities concentration or serious occupation, the use of conventional excavation of the ground method can not repair and update the pipeline, can be used for water supply, sewage and gas pipeline repair, can also be used for chemical and other industrial pipeline repair. The use of this method to repair pipelines has the advantages of all-weather construction, no joints and good fluidity, and can adapt to non-circular sections and curved pipe sections, but its limitations are high requirements for pipeline cleaning, large cost, long resin curing time (generally more than 5 hours), and each section of construction braided pipe needs to be customized separately.
3. Spraying methodThe spraying method is usually used as a pipeline lining for anti-corrosion purposes, and it is a technology that applies anti-corrosion and structural lining to pipelines. The high-speed rotating sprinkler head is pulled by the winch through the pipe, spraying and depositing the lining material onto the entire inner surface of the pipe under the action of centrifugal force. This is the technology used to coat the cement mortar in cast iron, cement and steel pipes, which prevents pipe joints, water discoloration and hydraulic loss. Recently, epoxy resins have been approved for use in drinking water pipes, and due to the development of equipment and polymer formulations, structural spray liners have become a new method for repairing water and drainage pipes. Broken water and drainage pipes can be made of a high-strength fast-setting epoxy or polyurea ester material. The construction operation can be accessed from the surface, which avoids the need to excavate the road from existing manholes. This method is usually suitable for pipe rehabilitation with a diameter of 150 to 600 mm.
4. Local repair method: Resin grouting or chemical grouting is carried out at the damaged part of the pipeline. Due to external force or joint failure, when a local rupture is formed inside the pipeline, remote control grouting (resin) can be considered to plug the local failure. There are four main problems that can be solved by the fix:
1) Make loose, separate, unreinforced old pipes have a bearing capacity similar to that of stone arches;
2) provide additional structural properties to help the damaged pipe withstand structural loads
3) It has the function of anti-repair;
4) It can replace the lost pipe section. Chemical grouting with ureamate or similar materials has been used for many years in drain pipe rehabilitation, especially in North America. The use of remote control or human access method to grouting failed joints and cracks can prevent leakage of the pipeline and the formation of cavities around the pipe.
5. Stainless steel lining technology: Stainless steel sheet lining repair technology is to line the steel plate inside the pipeline, and the steel plate is in the form of coil plate, which is welded inside the pipeline and formed as a whole. Lining the steel plate inside the pipeline can increase the overall compressive resistance of the pipeline, and also has the effect of anti-seepage. Because the stainless steel lining can prevent the corrosion of the inner wall of the pipeline, reduce the roughness of the inner wall of the pipeline, increase the overflow flow of water, make the lined pipeline safer, lighter, more economical, and have a longer service life, so as to achieve the purpose of repair. Judging from the repair of old pipes at home and abroad, this technology has been widely used in sewage pipelines due to its strong adaptability, reliable quality, and water operation. The gap between the stainless steel sheet lining and the inner wall of the original pipeline is filled with cement mortar by grouting method, which is a solvent-free, low-shrinkage, strong adhesive polymer material, and after the grouting liquid is solidified, a solid interlayer fixed inside and outside is formed to ensure the repair quality and effect of the pipeline. Stainless steel sheet is used as the repair material for the lining of water supply pipes, which has more advantages than other kinds of materials. It is corrosion-resistant, non-scaling, small friction, non-toxic and non-polluting, and has a longer buried service life than steel pipes and cast iron pipes, and has been widely recognized in the international and domestic water supply industry.
6. Fragmented pipe method pipeline repair technology Fragmented pipe method pipeline repair technology can be divided into two processes according to the power source: static crushing (splitting) pipe method and pneumatic crushing pipe method, static crushing (cracking) pipe method is to break the original pipeline under the action of static force or cut the original pipeline through a cutting tool, and then expand it with an expansion headThe pneumatic pipe crushing method relies on the impact force generated by the pneumatic impact hammer to break the original pipeline.
7.Compared with the traditional open-pit method, the spiral winding repair technology (SPRTMPE) is regarded as one of the quieter construction methods. The winding machine uses spiral winding technology to wind the polyethylene strips reinforced with steel into the shape of a pipe. The polyethylene material is then fused to these steel-reinforced polyethylene strips to create a new pipe inside the main pipe. This method avoids the use of air compressors and boilers, and also eliminates the need for dragging and rubbing of the lining material.