5 Structural Forms of Hydraulic Piping Joints

Hydraulic piping joints are connectors between oil pipes and oil pipes. The connectors between oil pipes and hydraulic components should meet the requirements of firm connection, reliable sealing, small shape and size, small pressure drop, large flow capacity, and easy installation and disassembly. Therefore, full attention should be paid to pipe joints. High-quality hydraulic tubes joints with good sealing are an important reason for hydraulic system leakage!

What are the five structural forms of hydraulic tube joints?

In hydraulic systems, pipe flange connections are usually used for metal pipes with an outer diameter greater than 50mm. For the connection of small-diameter oil pipes and pipe joints, there are many commonly used pipe joints, which can be divided into straight-through type, angle-through type, three-way type, four-way type, etc. according to the number of passages and flow direction; according to the different connection methods between oil pipes and pipe joints, they can be divided into flaring type, welding type, ferrule type, etc.

Ordinary fine thread can be used for the connection between hydraulic tube joints and other components. For high-pressure systems, combined sealing gaskets can be used to seal the joint body and connecting parts; for medium and low-pressure systems, tapered threads can be directly used to connect to the body.

1. Flared pipe joint

Before assembly, place the connected pipe on a special tool, and then use a nut to press the pipe sleeve and pipe onto the conical surface on the joint body to form a seal. The function of the pipe sleeve is to prevent the pipe from rotating when the nut is tightened. This hydraulic tube joint has a simple structure, reliable connection, convenient assembly and maintenance, and is suitable for the connection of low-pressure thin-walled pipes such as copper pipes and thin-walled steel pipes.

2. Casing pipe joint

If it is a casing joint structure. The casing joint consists of a joint body nut and a casing pipe. The casing pipe is a metal ring with an inner round end with a sharp blade. When the nut is tightened, the casing contacts the cone in the joint body to form a seal, and at the same time cuts the surface of the oil pipe, which plays a role in connection and sealing. This hydraulic tube joint has good performance, light weight, small size, reliable sealing, and convenient work. It is widely used in hydraulic systems, and the working pressure can reach 32MPa. It requires high-precision pipes.

3. Welded pipe joints

If it is a welded pipe joint structure and connection, first put the nut on the pipe, then weld the pipe and the end of the oil pipe together, and when tightening the nut, connect the pipe and the joint body. There are two forms of sealing at the joint of the pipe and the joint body: one is to use the spherical surface and the conical surface to contact the seal; the other is to use the end face plus the O-ring. The former has self-positioning and the installation requirements are not strict, but the sealing performance is poor, the use pressure is not high, and it is suitable for medium and low pressure systems; the latter can be used in high pressure systems, and the use pressure can reach 32MPa. The welded pipe joint has a simple structure, easy manufacturing, reliable operation, and low requirements for pipe size accuracy. But the welding quality requirements are high.

4. Hose joints

If it is a hose joint, in addition to the working reliability of general pipe joints, it should also have vibration tolerance, impact resistance, and resistance to repeated flexion and extension. There are two common types: detachable and fastened, each with three forms: A.B.C. Type A uses a welded pipe joint, type B uses a ferrule pipe joint, and type C uses a flared pipe joint.

5. Quick-change joints

If a certain part of the pipeline needs to be disassembled frequently, a quick-change joint can be used. This type of joint has a more complex structure and greater local resistance loss.

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