Causes of oil leakage in hydraulic system pipelines

There are many types of pipelines used in the hydraulic system. According to the working pressure and installation position of the hydraulic system, steel pipes (seamless hydraulic tube ) , copper pipes, rubber pipes, nylon pipes and plastic pipes are selected. Once these pipelines are damaged and leaking oil, it will pollute the environment and affect the normal function of the system, or endanger safety in severe cases. This article analyzes and summarizes the causes of oil leakage in hydraulic pipelines and the corresponding countermeasures.

Analysis of the cause of oil leakage:

1. Poor quality of piping

When repairing or replacing hydraulic pipelines, if inferior pipelines are installed in the hydraulic system, oil leakage will occur due to their low pressure-bearing capacity and short service life. The poor quality of hard tubing is mainly manifested by uneven wall thickness, which reduces the load-bearing capacity; inferior hoses are mainly caused by poor rubber quality, insufficient steel wire layer tension, and uneven weaving, resulting in insufficient load-bearing capacity. Under the impact of pressure oil, It is easy to cause pipeline damage and oil leakage.

2. The pipeline installation does not meet the requirements

a. Poorly bent pipeline

In the process of assembling the hard pipe, the pipe should be bent according to the specified bending radius, otherwise the pipe will have different bending internal stresses and gradually leak under the action of oil pressure. If the bending radius of the rigid pipe is too small, the outer pipe wall of the pipe will become thinner, and the inner pipe wall will have wrinkles, so that the pipe has a great internal stress at the bend, and the strength is greatly reduced. The road is prone to transverse cracks and oil leakage; if a large ellipse occurs in the bending part of the hard pipe, longitudinal cracks and oil leakage are likely to occur when the oil pressure in the pipe fluctuates.

When the hose is installed, if the bending radius does not meet the requirements or the hose is twisted, it will cause damage to the hose and oil leakage.

b. The installation and fixation of the pipeline does not meet the requirements

Common improper installation and fixation include:
(1) When installing oil pipes, regardless of whether the length, angle, and thread of the pipes are suitable for assembly, the pipes are deformed and installation stress is generated. At the same time, it is easy to damage the pipes and reduce their strength;
(2) When installing the oil pipe, do not pay attention to fixing it. When the bolts are tightened, the pipe will rotate together, causing the pipe to twist or collide with other parts and cause friction, which will shorten the service life of the pipe;
(3) Sometimes the pipe clamps are too loose, which increases the friction and vibration between the pipe and the clamp; sometimes they are too tight, causing the pipe surface (especially aluminum pipe) to be clamped and deformed; these conditions will damage the pipe and cause damage to the pipe. Oil spill
(4) The tightening torque of the pipeline joint is severely exceeded, causing the bell mouth of the joint to be broken, the thread is strained, and the tripping leads to a serious oil leakage accident.


3. Fatigue damage or aging of hydraulic pipeline

The observation and analysis of a large number of hard hydraulic pipeline fractures show that the rupture of the hard pipeline is a kind of fatigue failure, so there must be an alternating load on the pipeline. When the hydraulic system is working, the hydraulic pipeline has to withstand higher pressure, coupled with the combined effect of alternating stress caused by pressure instability, vibration stress caused by equipment vibration, assembly stress, etc., so that the hard tube is in the material defect. , Stress concentration occurs at the corrosion point or damage, and the pipeline is fatigued and fractured and oil leaks. For rubber pipelines, they will age, harden and crack from places with high temperature, high pressure, bends, and serious distortions, and finally the pipeline will burst and leak oil. Long Ben hydraulic steel pipe

4. Hydraulic oil pollution and pipeline surface pollution

When the hydraulic oil is contaminated, the oil pipe will be worn and corroded, and the rupture of the pipeline will be accelerated and the oil will leak. Moreover, this kind of damage is not easy to be found, and the damage is more serious.

Since the hydraulic system is easily contaminated, hydraulic oil containing solid contaminants is similar to the abrasive used for grinding metal processing surfaces, increasing the friction between the oil and the inner wall of the pipeline. Moreover, the hardness of solid pollutant particles is usually much higher than the hardness of the inner wall material of the catheter, which accelerates the abrasion of the inner wall of the catheter and even scratches the inner wall. Especially when the flow rate of the liquid is high and unstable (fast flow rate and large pressure pulsation), the material on the inner wall of the catheter will be impacted and peeled off.

When the hydraulic oil contains water, it will promote the hydraulic oil to form an emulsion, reduce the lubrication and anti-corrosion effect of the hydraulic oil, and accelerate the wear and corrosion of the inner wall of the pipeline. When the hydraulic oil contains a lot of air bubbles, the air bubbles in the high-pressure pipeline are compressed, and the surrounding oil flows to the space originally occupied by the air bubbles at high speed, causing strong hydraulic shock. Under the impact of the high-pressure liquid mixture, the inner wall of the pipeline is affected. Corroded and peeled off. These conditions will eventually rupture the pipeline and cause oil leakage.
 

In addition, the outer surface of the pipeline is often stained with moisture, sludge and dust. If the protective layer is damaged, it is easy to corrode, resulting in a decrease in strength, until blasting oil occurs from high temperature, high pressure, bending, and serious distortion.

Material of hydraulic pipe: Ordinary carbon steel pipe is used more in large hydraulic systems, and most of stainless steel is used in special pipelines. The hydraulic pipe is relatively less used. The most common is carbon steel pipe.

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