Grooved pipe connection technology, also known as clamp connection technology, has become the first technology for liquid and gas pipeline connections. Although this technology was developed later in China than abroad, due to its advanced technology, it was quickly adopted in China. accepted by the market. From the beginning of research and development in 1998 to the present, after just a few years of development and application, it has gradually replaced the two traditional pipeline connection methods of flange and welding. Not only is the technology more mature, but also widely recognized by the market, and it has been actively guided by national laws and regulations.

The application of grooved pipe connection technology makes the complex pipe connection process simple, fast and convenient. A big step forward in plumbing technology. As a new type of pipe connection technology, grooved pipe connection has obvious advantages of convenient construction and reliable quality.

First, the advantages of grooved pipe connection

1. Simple operation

The connection operation of grooved pipe fittings is very simple, no special professional skills are required, and ordinary workers can operate it after simple training. This is because the product has incorporated a large number of fine technical parts into the finished product in a factory-like fashion. It only takes a few minutes to connect a pipe fitting, which greatly simplifies the technical difficulty of on-site operation and saves man-hours, thereby stabilizing the project quality and improving work efficiency. This is also the general direction of the development of installation technology.

However, the traditional welding and flange connection pipeline connection method not only requires welding workers with corresponding skills, but also is time-consuming, difficult for workers to operate, and there is pollution from welding fumes. Due to differences in operating 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, since the grooved pipe fittings are finished parts, the operation space required on site is small, and the installation can be realized against the wall and the corner, and the operation difficulty is greatly reduced, thereby saving the floor space and beautifying the effect of the pipe installation.

2. The original characteristics of the pipeline are not affected

For grooved pipe connection, only a groove is extruded on the outer surface of the connected pipe with a rolling groove machine, without destroying the inner wall structure of the pipe, which is a unique technical advantage of grooved pipe connection. Many pipes with anti-corrosion coatings on their inner walls would be damaged if conventional welding operations were used. Therefore, the specification stipulates that galvanized pipes, plastic-lined steel pipes, steel-plastic composite pipes, etc. shall not be welded and flanged, otherwise secondary treatment is required.

3. Conducive to construction safety

Using grooved pipe connection technology, only cutting machine, rolling groove machine and handle for tightening bolts are required on site, and the construction organization is convenient. The use of welding and flange connection requires complex power cables, cutting machines, welding machines, oxygen and acetylene gas cylinders, etc., which brings complexity to the construction organization, and there are hidden dangers of electric leakage and fire. . At the same time, the welding slag generated by welding and gas cutting will inevitably fall into the inside of the pipeline, and it is easy to cause pipeline valve parts and even equipment blockage during use, and also pollute the water quality in the pipeline.

In addition, welding and flange connection inevitably require long-term high-intensity aerial work, and production safety accidents are also prone to occur.

4. Good system stability and easy maintenance

The grooved pipe connection method has unique flexibility characteristics, making the pipeline anti-vibration, anti-shrinkage and expansion. Compared with welding and flange connection, the stability of the pipeline system is increased, and it is more suitable for temperature changes, thereby protecting The pipeline valve parts are reduced, and the damage to the structural parts caused by the pipeline stress is also reduced.

Due to the simple connection operation of grooved pipe fittings, the required operating space becomes smaller, which brings many convenient conditions for future maintenance. When the pipeline needs to be repaired and replaced, just loosen the two clamps to replace, rotate and modify a section of pipeline at will. There is no need to damage the surrounding walls, reducing maintenance time and maintenance costs.

5. Economic Analysis

Due to the simple operation of grooved pipe connection, labor-saving and time-saving, it has good economic benefits. Many articles have done economic analysis and believe that "with clamp connection, although the price of a single clamp is higher, the overall benefit of the entire pipe network installation is higher than that of flange connection".

Second, the connection method of grooved pipe fittings

A. Connection of grooved pipe fittings

1. Clamp installation

(1) Install the sealing ring: insert the sealing ring into one end of the pipe port, then align the other pipe port with the pipe port of this end, and move the sealing ring to the sealing surface of the two pipe ports. Both sides of the sealing ring should not protrude into the two pipes. groove.

(2) Install the joint: Loosen the two screws of the joint first, divide it into two pieces, put two shells on the sealing ring successively, insert the bolts, and tighten the nuts in turn to ensure that the two ends of the shell enter the grooves until they are tightened.

2. Mechanical tee and mechanical four-way installation

First remove one bolt from the shell, loosen the other nut until the end of the bolt, turn the lower shell about 90 degrees away from the upper shell, and place the outlet part of the upper shell at the opening of the nozzle and align it with the hole. , and then rotate the lower shell along the pipe end (if it is a mechanical cross, the lower shell method is the same as the upper shell) to make the upper and lower two pieces close together.

3. Flange installation

Install the flange piece: first loosen the screws on both sides, separate the two flange pieces, and install the ring key part of the two pieces of flange piece into the groove of the slotted pipe end, then insert and tighten the screws on both sides, and adjust the two flange pieces. The side gaps are similar.

Install the sealing ring: put the "C" opening of the sealing ring away from the flange, and push it into the groove of the inner diameter of the flange along the direction of the pipe end.

B, the setting of the bracket

1. Fixed bracket and guide bracket

The degree of freedom of the pipe can be controlled by the hanger and bracket, and the spring hanger can make the pipe fully free.

Flexible joints allow deflection in the pipeline. This feature has great advantages in installation and engineering piping, but the spacing between brackets and hangers in the pipeline should be carefully considered. The design and installation of the end support and hanger must carefully consider the cumulative elongation of the expansion caused by the increase in the internal pressure of the pipeline or the temperature rise. Fixed pivots can be used to prevent pipe displacement due to internal pressure and expansion. There are generally two types of fixed fulcrums: the main fixed fulcrum and the intermediate fixed fulcrum.

2. The influence of long pipelines

For long pipe systems, use intermediate fixing points to dissipate the forces due to pipe thermal expansion and internal pipe pressure. The weight of the pipes and equipment in the piping system needs to be supported by brackets, in addition, some brackets should allow the expansion and contraction of the pipes.

3. The influence of thermal expansion and contraction

The displacement caused by thermal changes in the piping system can be partially compensated by the piping method, and the flexible joint can effectively compensate for the pipeline displacement caused by thermal expansion and contraction. If the predicted displacement exceeds the total joint compensation in the system, a metal expansion joint must be installed at the relevant location in the system.

C. The actual installation of the support and hanger in the long standing road system

The long riser system mainly has the following forms:

(1) Flexible system risers are generally installed with fixed points at the bottom or top of each layer to prevent the pipes from bending, and the risers connected by branch pipes should have intermediate fixed points; or increase the number of flexible joints to provide sufficient deflection angle, to prevent damage to components or branches in the system.

(2) The riser treatment in the rigid system is very similar to the welding system. When there is thermal expansion, expansion joints and soft joints are used to prevent damage to the components in the system. Rigid joints are designed when connecting with the pump. This system is the most have advantage of.

(3) Combined system. When designing a combined riser system, rigid joints can be used to reduce the amount of guide brackets; flexible joints can partially compensate for the displacement caused by thermal expansion and contraction.