Rubber expansion joints can be divided into two types of Open ArchType Arch and Filled ArchType closed Arch to the middle Arch area, as shown in FIG. 5. The choice of these two types shall be determined according to the medium in the pipeline. If the medium contains sand components, in the process of medium transportation, sand particles will gather to the location of the arched area, easy to form eddy current and sand accumulation, which directly affects the service life of the expansion joint. At this time, it is more suitable to select the FILLED ARCH type rubber expansion joint. It should be noted that the two types of expansion joints have different ability to absorb displacement and should be taken into comprehensive consideration.
Performance characteristics and functions of rubber expansion joints rubber expansion joints are elastic connecting elements, which can be used in rigid pipe systems to provide necessary flexibility for pipes. The rubber expansion joint can be used to eliminate or release the stress of the pipe and can absorb the displacement change caused by the heat expansion and cold contraction of the pipe. Can absorb transverse, torsional, angular or parallel misaligned displacement. It can effectively suppress the surrounding vibration and eliminate the vibration in transmission to prevent equipment damage or failure. Can suppress the sound transmission, can reduce the noise.
Rubber expansion joints can be designed with up to four arches, which have greater absorbency than single arches. The absorptive capacity of multiple arches can be multiplied by the absorptive capacity of a single arch. The elastomer of rubber expansion joint can be natural rubber or synthetic rubber, which can meet the special requirements of different industrial applications. The strength of the expansion joint comes from the combination of the fabric and the inner metal reinforcement. Expansion joint special design, special liner and covering layer, can meet the corrosive medium transportation needs, ensure the service life is not affected. If the use of special liner, can be more effective delivery of media containing impurities, such as: increase the thickness of the rubber wall, the use of steel liner. Different types of expansion joint and heat-resistant, expansion joint can withstand - temperature of 40 ℃ to 205 ℃.
3.3 flanges and bolts that are required to be matched with rubber expansion joints are usually purchased by the engineering company or supplied by the expansion joint supplier. The connection form is FF flange connection.
3.4 internal pressure thrust of rubber expansion joints when using rubber expansion joints, the role of internal pressure thrust must not be neglected. Fixed support should be set before and after the free rubber expansion joint to assume the role of internal pressure thrust of the expansion joint. When the expansion joint is installed in the pipeline, the internal pressure thrust generated by the expansion joint shall be the effective area of the expansion joint multiplied by the maximum pressure in the pipeline. The calculation formula of internal pressure thrust T is shown in FIG. 6. Where D is the effective inner diameter of the expansion joint and P is the design pressure [4-6].