Cautions on the use of ferrule fittings

Card sleeve pipe joints with simple structure, easy to use and do not have the advantages of welding. However, in the high-pressure hydraulic system, improper operation will often result in leakage, affecting its promotion and use. After years of practice, the author summed up some experience and achieved good results. As shown in the drawings, a ferrule fitting is mainly composed of a connector body 1 having a tapered hole of 24 degrees, a ferrule 2 with a sharp inner edge, and a pressing nut 3 for pressing. When the nut 3 is tightened, the ferrule 2 is pushed into the taper hole of 24 degrees and deformed, so that the ferrule and the conical surface of the ferrule body form a spherical contact seal; at the same time, the inner cutting edge of the ferrule is embedded in the outer wall of the steel pipe 4, The outer wall is pressed out of a circular groove, which plays a reliable role in sealing. Steel pipe is best to eliminate the stress annealing of the 20 # extubation, which is conducive to the inner wall of the ferrule embedded steel pipe outer surface, play a reliable seal. (1) pre-installed ① sleeve ferrule pre-installed is the most important part of a direct impact on the reliability of the seal. Generally require a dedicated pre-installed. Small diameter pipe joints can be pre-installed on the vise. The specific approach is to use a connector body as the mother, the nut, the sleeve can be pressed onto the tube. The main card straight through the pipe joints, straight through the card sets of the first type, the three-way pipe fittings and other types. The author found that even the same batch of goods from the same manufacturer, these joints are often the depth of the tapered hole is not the same, resulting in a leak, and this problem is often overlooked. The correct approach should be, what kind of connector body at one end of the tube connection, the corresponding connector is pre-installed with the same type of connector, so as to minimize the problem of leakage. ② pipe end should be flush. After sawing the pipe should be polished and other tools on the grinding wheel flush, and remove burrs, clean and use high-pressure air after blowing. ③ pre-installed, should try to maintain the coaxiality of the tube and the connector body, if the tube is too large deflection can cause seal failure. ④ pre-installed power should not be too large. Should make the inner edge of the sleeve just embedded in the pipe wall, the sleeve should not be significantly deformed. In the pipeline connection, then the provisions of the tightening force assembly. Tightening force of φ6-10mm ferrule is 64-115n, φ16mmr 259n, φ18mm is 450n. If the pre-installed sleeve deformation serious, will lose the sealing effect. (2) It is forbidden to add packing materials such as sealant. Someone in order to achieve a better sealing effect, apply a sealant on the ferrule, resulting in the sealant being stormed into the hydraulic system, causing the clogging of the damping orifice of the hydraulic element. (3) When connecting pipelines, the pipe should have enough deformation allowance to avoid the pipe being subjected to tensile stress. (4) When connecting the pipeline, it should be avoided to subject it to lateral force and lateral force to cause the seal to be lax. (5) when connecting the pipe, should be one-time tight, to avoid multiple disassembly, otherwise it will make the sealing performance worse.