How to install hydraulic hose joints to ensure good air tightness

The installation of hydraulic fittings is generally divided into the following 5 steps:

1. Pre-installed

①. An important part of the pre-installation of hydraulic joints and fittings directly affects the reliability of the seal. Usually a dedicated preprocessor is required.

Fittings with small diameters can be pre-assembled in a vise. The specific method is to use a joint as the mother body, and press the nut and the ferrule onto the pipe. There are mainly ferrule-type straight-through pipe joints, ferrule-type end-through joints, ferrule-type three-way pipe joints and other types.

②. The end face of the pipe should be flush

After the pipe is cut off, it should be polished on a grinding wheel and other tools, and the burrs should be removed, cleaned and blown with high-pressure air before use.

③. During pre-installation, the coaxiality of the pipe and the joint body should be maintained as much as possible. If the deflection of the pipe is too large, the seal will fail.

④. The preloading force should not be too large so that the inner edge of the ferrule is just embedded in the outer wall of the pipe, and the ferrule should not be significantly deformed. When connecting the pipes, assemble them according to the specified tightening force. The tightening force of ф6-1 ferrule is 64-115n, 16фmmr 259n, and ф18mm is 450n. If the ferrule is severely deformed during pre-installation, the sealing effect will be lost.

2. It is forbidden to add fillers such as sealant

In order to achieve better sealing effect, some people apply sealant on the ferrule, as a result, the sealant is flushed into the hydraulic system, causing failures such as blockage of hydraulic component holes.

3. When connecting the pipeline, the pipe should have enough deformation allowance to avoid the pipe being subjected to tensile force.

4. When connecting the pipeline, it should be avoided to be subjected to lateral force. If the lateral force is too large, the sealing will not be tight.

5. When connecting the pipeline, it should be connected at one time to avoid multiple disassembly, otherwise the sealing performance will be deteriorated.

The requirements for the installation of joint fittings are as follows:

①.According to the requirements, the pipes that need to be pickled should be pickled first;

②. Use sawing machine or special pipe cutting machine and other equipment to cut the pipe according to the required length. It is not allowed to use melting (such as flame cutting) or grinding wheel cutting; remove the inner and outer circular burrs, metal chips and dirt on the pipe end; remove the rust inhibitor and dirt; at the same time, ensure the roundness of the pipe;

③. Put the nut and the ferrule into the pipe successively, the front edge of the ferrule (small diameter end) is at least 3mm away from the pipe mouth, and then insert the pipe into the taper hole in the joint body until it reaches it;

④. Slowly tighten the nut, while turning the tube until it does not move, then tighten the nut 2/3 to 4/3 turns;

⑤. Disassemble and check whether the ferrule has been cut into the pipe and whether the position is correct. The ferrule is not allowed to have axial movement, and can be rotated slightly;

⑥. Re-tighten the nut after passing the inspection.