Common problems caused by improper installation of external wire joints

Common problems and causes caused by improper installation

1. Leakage issue

Leakage at threaded connection

Reason:

Untightened or insufficient torque: The thread pre tightening force does not meet the sealing requirements, causing the medium to leak out from the thread gap.

Excessive tightening: Stress concentration at the root of the thread leads to plastic deformation or cracking, damaging the sealing surface.

Thread mismatch: Mixing metric threads (such as M series) with imperial threads (such as G, NPT) results in loose engagement.

Incorrect use of sealant: Failure to apply sealant, insufficient amount of sealant, or improper selection (such as using ordinary sealant under high temperature conditions).

Case: During the installation of a hydraulic system joint, a torque wrench was not used and only tightened based on experience, resulting in leakage at the thread under high pressure. After replacing the joint, it still recurred, and it was ultimately discovered that the thread tolerance exceeded the standard.

Seal damage and leakage

Reason:

Incorrect installation direction of sealing components: such as installing the O-ring in reverse or reversing the direction of the combination gasket, resulting in sealing failure.

Scratches on seals: Uneven cutting of pipelines, burrs scratching the sealing surface or seals.

Seal aging: Long term exposure to high temperature and highly corrosive media without timely replacement.

Case: The integrity of the O-ring was not checked during the installation of the pneumatic pipeline joint, and after one week of operation, the seal aged and ruptured, resulting in air leakage.

2. Vibration and looseness

Reason:

No anti loosening measures were taken: relying solely on thread pre tightening force, without using double nuts, spring washers, or anti loosening glue.

System vibration frequency matching: The vibration frequency of the pipeline is close to the natural frequency of the joint, causing resonance and loosening.

The impact of thermal expansion and contraction: Without reserved expansion and contraction, temperature changes can cause the expansion and contraction joints of the pipeline to become loose.

Case: The hydraulic cylinder joint of construction machinery became loose during frequent start stop operations. Due to the lack of anti loosening glue and excessive spacing between the pipeline fixing brackets (1.5m), the problem was ultimately solved by shortening the bracket spacing to 0.8m and adding anti loosening glue.

3. Pipeline damage

Twisted or dented pipeline

Reason:

Forcefully twisting during installation: Forcefully bending the pipeline to align the joint position causes stress concentration.

Insufficient bending radius: Without using a pipe bender, the manual bending radius is less than 3 times the pipe diameter, resulting in thinning of the pipe wall.

Case: During the installation of a pneumatic pipeline in an automated production line, it was manually bent. After running for three months, the pipeline collapsed and became blocked. The problem was resolved by using a pipe bender to control the bending radius.

Pipelines and joints have different axes

Reason:

Fixed bracket not adjusted: The pipeline was not fixed with a bracket after installation, resulting in the joint bearing eccentric force.

The stiffness mismatch between the joint and the pipeline material: For example, if a metal joint is connected to a plastic pipeline, long-term eccentricity can cause the pipeline to rupture.

Case: Due to the large difference in stiffness between metal joints and plastic pipes, the hydraulic pipeline of chemical equipment broke at the connection after one year of operation. The problem was solved by using flexible joints for transition.

4. Joint breakage or damage

Reason:

Material selection error: Low voltage connectors are used for high voltage systems, or ordinary carbon steel connectors are used for strongly corrosive media.

Excessive tightening: The torque exceeds the load-bearing capacity of the joint, causing the root of the thread to break.

Improper installation tools: Using adjustable wrenches or pliers can cause uneven stress on the threads and deformation.

Case: A high-pressure hydraulic system mistakenly used a low-pressure joint, and after running for two weeks, the joint burst. After replacing it with a high-pressure alloy steel joint, it returned to normal.