Situación actual y tendencia de desarrollo de la tecnología de reparación de tuberías

Me. Introducción

Pipeline repair technology has mainly emerged with the aging of urban infrastructure. Abastecimiento de agua y drenaje urbano, sistemas de gasoductos y otros sistemas de tuberías, como otras estructuras antiguas, son cada vez más propensos a ser dañados.
Las tuberías están profundamente enterradas e invisibles, y es imposible comprender las condiciones específicas de las tuberías subterráneas hasta cierto punto., and sometimes these facilities are destroyed without any warning. As a result of the damage, the operation is interrupted, and the pipeline owners not only have to bear huge economic losses, but also the relevant parties have to bear great public pressure. The replacement of pipelines is not only costly, but also brings environmental and social problems, which in a certain sense is no longer a matter for pipeline owners and users. Busy urban traffic, protección del medio ambiente, heritage reserves, crop and vegetation reserves, as well as highways, railways and buildings, ríos, etcetera. require pipeline owners and government officials to minimize excavation in pipeline construction and management quantity.
As part of trenchless construction technology, pipeline repair technology was first developed in the UK, US and Japan in the late 1970s. Many sewage pipes and water pipes in western developed countries have a history of more than 100 Años, so construction techniques for repairing or replacing these pipes are required. En primer lugar, the internal condition of the pipeline needs to be ascertained, so CCTV cameras were developed to meet this requirement. The use of excavation-free repair technology is a high-tech method in the case of identified pipeline damage, and the development of pipeline repair technology begins. CIPP was first developed and applied, and then technologies such as lined PE pipes were developed and applied one after another. The progress of pipeline repair technology is developed with the progress of material technology and electronic technology. The development of material technology provides pipeline repair technology with repair materials that can be arbitrarily changed in shape according to requirements. The development of electronic technology makes it possible to detect and evaluate pipelines without excavation, and remote control robots can repair underground pipelines.
Pipeline repair technology continues to mature and has become an important part of pipeline construction technology, which has been confirmed by the Prague International Conference on Trenchless Technology in 2001. The conference was attended by 32 companies representing the current level of trenchless technology for pipelines, of which 15 are pipeline repair companies.
Worldwide, there are more than 60 trenchless pipeline repair and replacement methods currently in existence or under development, and the number of companies involved in pipeline repair is beyond imagination. Entering keywords on the Internet: tubería, repair, the search results actually gave more than 48,000 pieces of information, most of which are webpages of enterprises engaged in pipeline repair. The specific number of enterprises is not important, such webpage or website information is enough to illustrate the space occupied by pipeline repair technology in the international market.

II. Foreign pipeline repair technology and its application status

It is a common practice to build various pipelines underground. In order to reduce the negative impact on society, various trenchless technologies have been developed one after another. As an important branch of trenchless pipeline technology, pipeline repair technology has also received more and more attention. With more and more attention, the process methods of pipeline repair technology emerge in an endless stream.

1. Local and wellhead repair technology

The Beaver partial repair equipment launched by the Danish company has entered the market in the second half of 1997. The raw material used in this equipment is glass fiber layer of epoxy resin. After a section of lining is put into the pipeline, it is expanded by steam pressure to make it close to the pipe wall. The maintenance process takes about 1 Hora. This technique is suitable for repairing broken pipes, Grietas, misalignments, open joints, and damaged branches. Liners are commercially available in a variety of lengths, diameters and wall thicknesses.
A PanelLok device has been developed in Australia to update maintenance wells, storm wells and maintenance personnel access. The device uses a preformed PVC tape that is helically wound to fit snugly into existing pipes. The PVC tape can be fed directly into the pipeline through the opening of the maintenance well without removing the cover plate. The PVC tape joints have overlapping locks, which play the role of waterproof sealing.
British pipeline repair contractors have recently launched AMEX-10, a trenchless system for repairing pipe joints and circumferential cracks in pipes, which can be used to repair large diameter pipes. The system provides a small end face rubber seal against the inner surface of the steel pipe under the pressure of an expandable stainless steel ring. For gas pipelines, NBR rubber can be used as sealing material, and for water pipes, EDPM rubber can be used as sealing material. The system is suitable for the repair of pipes with a diameter of 600-3000mm. The California company’s poly-Triplex liners are fabricated in situ with a layer of fiberglass tissue with an impermeable inner membrane for access repairs. The fibrous tissue is formed into the shape of a manhole before being dipped in epoxy, the balloon is lowered into place, then pressurized, and excess liner removed.

2. Restoration technology based on polyolefin material

Polyethylene material has been identified over the past few years as a material of choice for industrial piping, city gas piping and municipal sewer systems. Polyethylene materials are chemically resistant and have a long service life, and their excellent weldability provides ideal connections. The number of connections to components in any system should be minimized in order to reduce potential leak points. The technology of relining and repairing without excavation of large length is not only beneficial to the environment and low cost, but also can reduce the number of joints of the pipeline to a minimum. Repaired pipes have higher reliability and longer service life than newly constructed pipes. Polyethylene materials have been widely used in the repair of various types of piping systems, including structural repair and non-structural repair systems. The technical process method has also been developed from the initial insertion method (diameter reduction insertion) to a variety of process methods. The more famous process methods are the folding deformation method, the hot drawing method, the cold rolling method and the Trolining repair system. Using this method, the cross-sectional area of ​​the pipeline after repair is reduced to a certain extent, and there is no gap between the lining and the original pipeline, so no sealing is required, and it can be used for long-distance pipeline repair. Different methods have different requirements for technicians.
(1) Folding deformation method. Can be used for structural and non-structural repairs. U-shaped liner pipe uses a jointless HDPE pipe, uses the shape memory properties of the material to make it into a U shape, and sends the liner into the pipe, and then uses physical conditions to restore it to the original pipe shape. The advantage of this method is the speed of construction, the use of continuous long pipes, and no joints.
(2) Hot drawing method. This method was developed by British Gas. Durante la construcción, after heating, the lining pipe is drawn through a die or pressing wheel, so that the molecular chain of the lining pipe is recombined and the diameter of the pipe is reduced. For a 4-inch pipe, the pipe diameter is reduced by about 20%, and for a 24-inch pipe, the pipe diameter is reduced by about 7%. After being deformed in place, it relies on the memory function of the original structure of the plastic long molecule, so that its diameter gradually returns to the same shape and size as the old tube.
(3) Cold drawing method. Developed by a British company, it uses a hydraulic jacking device to push plastic pipes to a group of rolling mills to reduce the diameter of the pipes. Durante la construcción, standard medium-density or high-density polyethylene pipes are butt-welded into appropriate lengths, and then cold-rolled on site to reduce the diameter and facilitate insertion into the old pipes. When the liner is in place, apply pressure to it to restore the original size, the same as the old tube shape
into a tight fit.
(4) Trolining repair system is an innovation of sewage pipeline repair technology. As far as pipes are concerned, a high overall quality can be achieved. The system is suitable for fault repair of pipes with different diameters, and the size of the lining is complete, which provides many possibilities for deformation and combination. It can be used to repair all sewage pipelines from 150mm to 1600mm in diameter of highway, regardless of size, and regardless of the complexity of section size and shape. por lo tanto, this type of high-density polyethylene lining is used in a wide range, including prefabricated segment lengths, cross-sectional dimensions, and shapes, etcetera., for various occasions. This liner is welded into a cylindrical HDPE element with many protrusions on the outer surface of the element. The liner is inserted into the broken pipe through the existing access hole, and then the annular space formed by the protrusion is grouted with a special spray mixture injected with an injector. This high-strength material holds the lining permanently in place. This repair technology is more like a composite pipeline in which concrete and plastic are poured on site using the existing pipeline as a mold, y al mismo tiempo, it utilizes other functions of the existing pipeline. This system is no longer a repair in the general sense. exact.

3. In-situ curing repair technology based on thermosetting resin

The use of styrene-based resins has decreased for environmental reasons in favor of environmentally more popular resins. Other resins, such as vinyl ester resins, are also used in some special applications, especially for industrial piping. The medium of industrial pipes is more corrosive than sewage, and the distinction between different products that meet specific requirements makes trenchless repair technology used in new areas, especially in the industrial pipe market. The reason for using UV light instead of hot water hardening resin is that the speed of using UV curable resin is faster and the resulting cost benefit is far greater than the increase in the cost of photosensitive resin, especially the repair of large diameter pipes can provide more favorable speed and benefit . While polyester resins are most commonly used, a variety of liner fibers have emerged, from needle linoleum to seamless advanced composites. Pressure pipe repair systems are used to repair water supply and cooling water pipes with small holes and corroded inner surfaces, while industrial wastewater pipe repair systems can withstand chemical environments and high temperatures. Both of these repair methods use water pressure to turn the repair pipe over according to the CIPP method, and then circulate the hot water to set the thermosetting resin. The inner lining of the pressure pipe includes a reinforcement layer that increases the surrounding strength.
The French company has developed the Photoliner system for repairing pipes from 200mm to 600mm in diameter without human access. It is also based on the CIPP method, using some UV lamps mounted on the robot to polymerize polyester resin. The company says the UV curing method requires less energy than traditional hot water or hot steam curing methods. Liners containing various materials are sent to the field packaged ready for use and do not need to be formulated on site. Now some companies have developed small turning equipment, which uses air pressure to turn over. The equipment is small and flexible, weighing only 35kg. With the air supply of 140L/min air compressor (below 0.3bar), the liner can be turned inside the liner. Turn it over and be able to enter 30°C air to accelerate curing in cold weather conditions. Aygus Flexible Pipeline in the UK has developed heat pipe repair technology to prevent corrosion leakage in mainline pipelines and prevent further corrosion. The heat pipe consists of a circular braided liner reinforced with high strength polyester resin encased in polyethylene. The length of the roll is 207m, the diameter is 76, 102, 152mm, it is in a soft C shape, and it is fixed on the steel pipe after derusting. It is semi-hard when cold, expands and softens after being heated by low-pressure steam, and is closely combined with the mother tube. The liner is rated at 10bar and has a design life of more than 50 Años. The method is approved for use on drinking water pipes by DWI in the UK and DVGW in Germany (German Association of Gas and Water Supply Technicians).
The American company recently introduced a new full-length liner system, PVCAlloypipeliner. It can pass through sharp bends in pipelines, displaced joints and reduced diameter pipelines, and can withstand most acid, alkali and salt fuels and corrosive media.

4. Repair technology based on liquid solidified materials

The representative ones mainly include cement mortar pipeline repair technology, epoxy resin and polyester resin spraying or extrusion coating repair technology, and the scope of application is low-pressure pipeline systems, including gas pipelines, water pipelines and sewage discharge systems.
The SHOT process technology developed by Tokyo Gas Company of Japan is widely used in small-diameter pipelines. It is mainly used to repair branch lines of pipelines. The advantage is that it can pass through elbows and tee fittings. The NEXT method is a process of extruding and coating rubber balls in the pipe. Además, there is also the “improved liquid phase method”, which also uses the method of piston balls to repair leakage points such as pipe joints. The resin covering method in the pipe and the resin sticking method for cast iron pipes basically belong to this scope. The biggest advantage of the liquid-phase solidified material pipeline repair technology is that it does not require a large operation pit, and can be repaired through any elbows and reducing pipes, and even in the case of tees, Válvulas, etcetera. Its application range is mainly small and medium-diameter pipes. The polymer cement mortar repair technology is mainly used to repair liquid pipelines, which can be adapted to a wide range of pipelines.

5. Pipeline repair supporting equipment technology

The technology of repairing pipes with robots has developed even more rapidly in the past decade. Actualmente, the use of robots is more economical and practical to replace traditional methods. Different types of remote-controlled cutters are widely used in trenchless technology, suitable for cutting tree roots intruded in sewage pipes, and re-opening after lining construction to facilitate main pipe connection.
Pipe cutters and pipe robots are among the new products for pipe repair that have come out in recent years. The HRF150 robotic pipe cutter of the French company is mounted on the HV140 tractor and can work in pipes with a diameter of 150-300mm. The motor drives the pipe cutting head to move in three dimensions. Driven by compressed air, the cutter head can be fitted with a variety of diamond or carbide cutting tools, and the HRF150 can be used with a variety of Hydrovideo pipe inspection systems.

III. Status Quo of Pipeline Repair Technology in China

The official start of China’s pipeline repair technology was in 1993. Before that, although cement lining technology was applied to old pipelines, it was mainly for the purpose of anti-corrosion. en 1993, according to the requirements of the group company, the Engineering Technology Research Institute of China National Petroleum Corporation implemented a pipeline repair and anti-corrosion demonstration project in Zhongyuan Oilfield. In the demonstration project, the Institute of Petroleum Engineering Technology organized scientific researchers to successfully develop “PCL composite structure pipeline repair technology” y “NCF in-situ curing pipeline repair technology”. These two technologies passed the expert review organized by the group company in 1994, and were subsequently popularized and applied in Zhongyuan Oilfield. “PCL composite structure pipeline repair technology” is the liquid-phase solidified material repair pipeline technology; “NCF in-situ curing pipeline repair technology” is equivalent to CIPP (in-situ curing repair technology). Subsequently, China Petroleum Engineering Technology Research Institute has successively completed the key projects of the head office, including the repair technology of interspersed plastic-lined pipelines, the repair technology of refined oil pipelines, the repair technology of high-impermeability inorganic mortar pipelines, and the in-situ solidification method gas-turning technology. The completion of these scientific research work has initially formed a pipeline repair technology system that can adapt to oilfield media in China’s pipeline repair technology. en 1998, practice proved that the pipeline repair technology of the Engineering Technology Research Institute did bring considerable economic benefits to oilfield companies and showed a good application prospect. As of the current incomplete statistics, there are about 10 pipeline repair companies There are about 20 companies, and some foreign businessmen have also begun to set foot in China’s pipeline repair field. But in general, China’s pipeline repair technology is still in its infancy, and there are mainly the following problems.
(1) The variety is single, the capacity is limited, it is not a series, and there is no matching of related products.
(2) Except that some units with strong technical strength have formulated enterprise standards, there is no unified standard and specification in China, which often results in unfounded construction. The restoration construction is generally carried out by the project contractor at will, and there is no standard specification to be found, and the final quality of the project is often very arbitrary.
(3) The equipment is poorly matched, and the technical adaptation range is narrow.
(4) The matching detection and evaluation technology before pipeline repair has not yet reached the level of use.
(5) The pipeline repair quality evaluation system has not been established. Because it is a concealed project, the quality supervision of the project is difficult, so that criminals can take advantage of it.

IV. Recommendations

In view of the current situation of China’s pipeline repair technology, it is suggested that while actively developing pipeline repair technology, the supporting work of corresponding standards of pipeline repair technology should keep up, so as to enable the pipeline repair industry to have a healthy development environment and avoid users due to lack of regulations. and standards can be found to cause problems and prevent the development of the entire industry from being adversely affected by the bad behavior of individual irresponsible enterprises.