Packaging & Delivery
Clamp type flexible pipe connection technology
1. The basic structure and working principle of the clamp
1.1 Basic structure of the clamp
The clamp type flexible pipe joint is that the clamp is stuck on the positioning ring of the pipe to ensure that the axial tension is not pulled when the bearing is sufficient, as shown in Fig. 1. Under normal circumstances, only 2 bolts are required for the clamps with the diameter below DN426; the clamps with the diameter above DN426 require 4 bolts to lock. Compared with flanges, bolt fastening is simple, convenient and reliable. The pipe connected by the clamp has a nozzle gap to ensure the flexibility of the pipe and the stress of the loose steel pipe. The sealing of the take-over gap is achieved by the clamped rubber ring. Clamp-type flexible pipe joints, which are widely used in China, are available in three types: ring type, shoulder type and groove type.
1.2 How the pipe card works
1.2.1 Installation of clamp type flexible pipe joints
Before installation, put the sealing rubber ring on the pipe, and then put the clamps and bolts. The medium inside the tube enters the apron, and the pressure of the medium is used to press the apron against the end of the tube to prevent leakage of the medium. The pressure of the medium acts on the inner cavity of the clamp through the apron.
1.2.2 apron sealing mechanism
The structure of the sealing rubber ring is "C" type. The elasticity of the apron can be used to seal the pipeline.
When the clamp is installed, the height of the rubber ring is higher than the height of the tube and the clamp, and the rubber ring is further squeezed by the inner space of the clamp, and the internal pressure is generated throughout the entire surface of the rubber ring, and the sealing effect is further enhanced.
When the medium exists in the pipeline, the medium enters the “C” cavity, which acts on the sealing lip of the apron, which increases the adhesion of the rubber ring and the pipeline, thereby achieving self-sealing. The greater the fluid pressure in the pipe, the greater the pressure of the apron and the better the sealing performance.
1.2.3 Difference between clamp seal and flange seal
The flange seal is acted upon by the bolt material by the bolt material. Since the tightening force of the bolt is difficult to achieve uniformity over the entire circumference, the fluid running in the pipe is highly susceptible to breaking the existing balance. Especially after increasing the pressure, the problem is more prominent, and running, running, dripping and leaking are serious.
In the clamp seal, the clamp seals the apron at the interface of the pipe and is completely pressed on one side. When the pipe is subjected to the pressure of the fluid, the inner surface of the apron will also be stressed, and it will be tightly attached to the contact surface, resulting in a better sealing effect.
1.3 Features of the clamp connection
1.3.1 Reasonable structure and high strength
The working state of the clamp is equivalent to the pressurized container, the axial force of the medium is completely borne by the clamp, and the bolt only bears the radial force of the clamp. Due to the limited width of the seal, the radial force is much smaller than the axial force. When the flange is connected, the bolt bears all the axial forces and the pressing force of the washer.
1.3.2 Good self-sealing effect
The sealing action relies on the pressing force of the medium in the pipe to the apron. The greater the pressure, the better the sealing performance. In order to prevent leakage of the medium without pressure, the inner diameter of the apron is smaller than the outer diameter of the end of the pipe end, and the apron has a pre-tightening force at the end pipe interface to prevent the medium from leaking when there is no pressure. Compared with the flange, the larger the pipe diameter, the higher the pressure, and the more prominent the advantage.
1.3.3 Pipe connection is in a flexible state
There is a gap between the clamp and the tube end, and the tube can have a small amount of activity in the clamp. Therefore, adjacent two end tubes allow a corner of 20 to 30. After the steel pipes are connected, there is a gap between the ends of the two steel pipes to allow the pipe to move axially, which can adapt to the expansion and contraction of the pipes; the rubber ring connection between the pipes can effectively reduce the mechanical vibration of more than 70%.
1.3.4 Easy to install and use
When the pipeline needs to be turned over, the four bolts of the joint can be removed to turn any angle without cutting and welding, which saves a lot of auxiliary workload and cost, reduces labor intensity and shortens the construction period. Compared with the flange connection, the work efficiency is 6-8 times, and the maintenance workload is small.
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As a new type of pipe joint technology, grooved pipe joints have obvious advantages of convenient construction and reliable quality. First, the connection of the pipe fittings 1. Clamp installation (1) Install the sealing ring: Put the sealing ring into one end of the pipe mouth, then align the other pipe mouth with the end pipe mouth, and move the sealing ring to the sealing surface of the two pipe ports. The sides of the seal should not protrude into the grooves of the two pipes. (2) Install the joint: first loosen the two screws of the joint, divide it into two pieces, put two pieces of shell on the sealing ring, insert the bolts, and tighten the nut in turn China Coal Industry Association mining fixed-point product manufacturers; national-level type to ensure that the two ends of the shell enter the groove until it is tightened. 2, mechanical three-way, mechanical four-way installation First remove the bolt from the outer casing, loosen the other nut until the end of the bolt, the lower shell is rotated about 90 degrees from the upper shell, the upper shell outlet part is placed in the tube The mouth opening is centered and aligned with the hole, and then the lower shell is rotated along the tube end (for example, the mechanical cross, the lower shell method is the same as the upper shell) to close the upper and lower parts. 3. Flange plate installation Install the flange piece: first loosen the screws on both sides, separate the two flanges, insert the ring-shaped key parts of the two flange pieces into the groove of the grooved pipe end, and then put the two sides Screw the screws tightly and adjust the clearance on both sides to be close. Install the sealing ring: push the “C” shaped opening of the sealing ring away from the flange and push it into the inner diameter groove of the flange along the tube end. Second, the bracket setting 1, the fixed bracket and the guide bracket The hanger and bracket can control the degree of freedom of the pipeline, the spring hanger can make the pipeline fully free. Flexible joints allow for deflection in the pipe. This feature has great advantages in installation and engineering piping, but careful consideration should be given to the spacing of the brackets and hangers in the piping. The design and installation of the end supports must be carefully considered for the cumulative elongation of the pipe when the internal pressure increases or the temperature rises. Fixed fulcrums can be used to prevent pipe displacement caused by internal pressure and expansion. There are two types of fixed fulcrums: the main fixed fulcrum and the intermediate fixed fulcrum. 2. Influence of long pipelines For long-pipe systems, intermediate fixed points are used to disperse the forces generated by the thermal expansion of the pipeline and the internal pressure of the pipeline. The weight of the piping and equipment in the piping system needs to be supported by the brackets. In addition, some brackets should allow the ducts to expand and contract. 3. Influence of thermal expansion and contraction The displacement caused by thermal changes in the piping system can be partially compensated by the piping method. The flexible joint can effectively compensate the displacement of the pipeline 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 of the system. Third, the actual installation of the support and hanger in the Changli Road system Long riser system mainly has the following forms: (1) Flexible system riser generally installs fixed points at the bottom or top of each layer to prevent the pipe from bending. The riser connected to the branch pipe should have an intermediate fixing point; 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 handling and welding system in the rigid system are very similar. When there is thermal expansion, the expansion joint and the soft joint are used to prevent the damage of the components in the system. When connecting with the pump, the rigid joint is designed. This system is the most have advantage of. (3) Combination 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 displacement caused by thermal expansion and contraction. Fourth, the quality control points Grooved pipe fittings in addition to the bracket settings should be reasonable, the biggest quality common problem is leakage. The main reasons for the leakage are as follows: 1. Before the construction of the grooved pipe fittings, the operators should be trained to familiarize the operators with the construction points and avoid the leakage caused by the incorrect installation process. 2, the pipe cut is not flat, easy to cause leakage. In actual construction, the flatness error of the nozzle should be no more than 1.5 mm to ensure that the butt joint is straight when connecting. 3. In the operation of the rubber ring, the rubber ring should be cleaned with a brush before use. 4. When the clamp is installed, the bolt should be tightened symmetrically so that the rubber ring is evenly stressed to ensure the pipeline is sealed. In view of these main causes of leakage, proper and effective measures are taken to minimize the leakage of pipeline connections and ensure the excellent construction of the project.