1. The grooved pipe fittings connection technology, also known as clamp connection technology, has become the first technology to connect liquid and gas pipelines at present. Although this technology was developed later in China than abroad, it was quickly accepted by the domestic market because of its advanced technology. From 1998 to now, after a few years of development and application, flange and welding have gradually replaced the two traditional pipeline connection methods. Not only is the technology more mature, but also the market is generally recognized, and has been actively guided by national laws and policies.
The application of grooved pipe fittings connection technology makes the complicated pipe connection process simple, fast and convenient. Pipeline connection technology has taken a big step forward.
2. Brief introduction of groove connection fittings groove connection fittings include two categories of products: 1) rigid joints, flexible joints, mechanical tees and groove flanges; 2) onclick = "g ('elbow') fittings for connection transition; > elbows, tees, four-way, Non-diameter pipe, blind plate, etc. The groove connecting pipe fittings which play the role of connecting and sealing are mainly composed of three parts: sealing rubber ring, clamp and locking bolt. The rubber sealing ring located in the inner layer is placed on the outer side of the connecting pipe, which coincides with the pre-rolled groove. Then the clamp is fastened on the outer part of the rubber ring, and then fastened with two bolts. Because the rubber sealing ring and clamp adopt special sealing structure design, the groove connection has good sealing performance, and with the increase of the fluid pressure in the pipe, its sealing performance increases accordingly. 3. Advantages of groove fittings connection 3.1 The connection operation of groove fittings is very simple, without special professional skills, ordinary workers can operate after simple training. This is because the products have incorporated a large number of fine technical parts into the finished products in a factory way. A pipe connection only takes a few minutes, which simplifies the technical difficulty of field operation to the greatest extent and saves man-hour, thus stabilizing the quality of the project and improving the work efficiency. This is also the general direction of installation technology development. The traditional way of pipe connection between welding and flange requires not only welding workers with corresponding skills, but also time-consuming, difficult operation of workers and pollution of welding fume. Due to the difference of operation space and welding skills, it is difficult to achieve satisfactory results in welding quality and appearance, thus affecting the overall quality of the project. In addition, because the grooved pipe fittings are finished products, the operation space needed in the field is small, and the installation of * wall * angle can be realized. The operation difficulty is greatly reduced, thus saving the floor area and beautifying the effect of pipeline installation.
3.2 The original characteristics of the pipeline are not affected by the connection of grooved pipe fittings. Only one groove is extruded by a grooving machine on the outer surface of the connected pipe, without destroying the inner wall structure of the pipeline. This is the unique technical advantage of grooved pipe fittings connection. If the traditional welding operation is adopted, many pipelines with anticorrosive coating on the inner wall will be damaged. Therefore, the specification stipulates that galvanized pipes, plastic-lined pipes, steel-plastic composite pipes and so on must not be welded and flanged connection, otherwise secondary treatment is required. 3.3 It is conducive to the safe use of grooved pipe fittings connection technology, the site only needs cutting machine, grooving machine and button bolt handles, construction organization is convenient. The use of welding and flange connection requires complex power cables, cutting tools, welding machines, oxygen and acetylene cylinders, which brings complexity to the construction organization, and there are also potential risks of leakage and fire. At the same time, the welding slag produced by welding and gas cutting inevitably falls into the pipeline, which is prone to pipe valves and even equipment blockage in use, and also pollutes the water quality in the pipeline. In addition, welding and flange connection inevitably require long time and high-intensity high-altitude operation, and are also prone to production safety accidents. 3.4 The system has good stability and convenient maintenance. The connection mode of grooved pipe fittings has unique flexible characteristics, which makes the pipeline have the ability of anti-vibration, anti-shrinkage and expansion. Compared with welding and flange connection, the stability of the pipeline system increases, which is more suitable for temperature change, thus protecting the pipeline valve fittings and reducing the pipeline stress. Damage to structural parts. Because the connection of grooved pipe fittings is easy to operate, the required operating space becomes smaller, which brings many convenient conditions for future maintenance. When the pipeline needs to be repaired and replaced, only two clamps can be loosened to replace, rotate and modify a section of pipeline at will. There is no need to destroy the surrounding walls, which reduces the maintenance time and cost. 3.5 Economic analysis shows that grooved pipe fittings have good economic benefits because of their simple connection operation and time saving. Many articles have done economic analysis, that "the use of clamp connection, although the price of a single part of the clamp is higher, but the overall benefit of the installation of the whole network is higher than the flange connection". In contrast, the flange connection is treated by secondary galvanizing (which is also necessary according to the requirements of specifications). Below the author will "Water Supply and Drainage" magazine in 2001, the fifth issue of "Trial on Pin Joint Piping System" the comparative results are abstracted as follows, for readers'reference. See Table 1 for details of the cost comparison of the two connection modes in Table 1: clamp connection cost/flange connection cost/flange connection cost/seamless steel pipe 30503.76 159*5mm seamless steel pipe 30503.76 clamp+onclick="g('elbow');>elbow+three-way 9143.00 flange+onclick="g('elbow');>elbow+three-way 8181.80 pipeline galvanized 95%.