Selection and Application of Uniform Thread for Hydraulic Hose Joints

If the hydraulic hose joints are not uniformly threaded, they will not fit. How can this problem be solved? Here is a solution for you.

1. UNC Coarse Thread Series This series is usually used in mass-produced bolts, screws, nuts and other general projects. Internal threads processed on materials with low tensile strength, such as castings, low carbon steel and other soft materials, should use coarse threads to obtain the best release strength for the internal threads. UNC thread is suitable for parts that require quick release or where corrosion and minor damage may occur.

2. UNF fine thread series This series is suitable for bolts, screws, nuts and other applications where coarse thread is not suitable. UNF external threads have a larger tensile stress area than coarse threads. When the release strength of external thread and matching internal thread is required to be equal to or higher than the tensile bearing capacity of external thread parts, fine thread should be used. Fine thread is also suitable for occasions where short screw-in length, small thread lead angle or wall thickness require fine thread pitch. If the maximum strength of the external thread is not required, the fine thread can also be used for internal threads processed on low-strength materials, but an appropriate screw-in length must be selected to meet the above-mentioned tripping strength requirements. Fine pitch threads 1 inch and smaller are suitable for bolts, screws, nuts, and other threaded fasteners. For sizes greater than 1 inch, fine pitch threads are not applicable unless the internal and external threads are of the same material.

3. UNEF ultra-fine thread series This series is suitable for occasions requiring short screwing length and smaller pitch, such as thin-walled pipes, thin nuts, short sleeves or short joints. In general, it also applies to several cases specified above for fine threads.

4. UN constant pitch series Various constant pitch series with 4, 6, 8, 12, 16, 20, 28 and 32 teeth per inch provide a wide range of special design requirements that cannot be met by UNC, UNF and UNEF series diameter/pitch combination. The constant pitch series is used for parts that have been assembled and disassembled many times or for parts that are conducive to re-threading. When selecting threads from the constant pitch series, the 8, 12 or 16 thread series listed should be preferred whenever possible.

5. High-temperature and high-strength applications For these applications, it is recommended to use the coarse thread series for threads with a size of 0.25~1 inch, and the 8-thread series for threads larger than 1 inch.