How to Clean The Inside of Hydraulic Tubes?

Hydraulic tubes, as a vital component of hydraulic systems, perform the critical task of transporting liquid media. However, over time, dirt, oil stains, and other impurities easily accumulate inside the pipes. These substances can negatively impact the proper functioning of the system. Therefore, cleaning the inside of hydraulic tubes is essential for maintaining hydraulic system performance.

According to the ISO 4406 standard for hydraulic fluid contamination levels and the NAS 1638 standard for cleanliness levels, hydraulic systems have strict requirements for fluid cleanliness. If the inside of the hydraulic tubes is not cleaned thoroughly, the system will struggle to meet the required standards, and the reliability and lifespan of the equipment will be severely impacted.

Internal Contaminants in Hydraulic Tubes

During long-term operation, hydraulic steel tubes are prone to accumulating various contaminants due to oil circulation, temperature fluctuations, and environmental influences. These contaminants primarily include:

1. Dirt and solid particles

Welding slag and cutting chips left over from hydraulic tube installation, as well as dust and sand from the environment, can enter the hydraulic tubes.

2. Oil stains and sludge

Hydraulic oil oxidizes or thermally degrades under high temperature and high pressure, forming thick sludge or deposits.

3. Moisture and rust products

Water seepage into the system, excessive air humidity, or incomplete cleaning.

4. Rubber and fiber impurities

Aging and peeling of seals and hoses due to high temperature and high pressure, or fiber debris introduced during maintenance.

Methods for Cleaning the Inside of Hydraulic Tubes

1. Mechanical cleaning

Operation

Use specialized cleaning tools, such as brushes or scrapers, to physically scrape the inside of the hydraulic tube to remove adhered dirt.

Features

Quickly remove large contaminants, but the cleanliness level is limited and usually requires use in conjunction with other methods.

Application

This method is suitable for larger diameter hydraulic tubes, but the procedure is more tedious.

2. Chemical cleaning

Operation

Use a cleaning agent or solvent to soak or circulate the inside of the hydraulic steel tube to dissolve and remove dirt.

Features

Chemical cleaning offers excellent cleaning results, but careful attention must be paid to the selection and safe use of cleaning agents.

Application

Chemical cleaning is suitable for hydraulic systems requiring high cleanliness.

3. High-Pressure water jet cleaning

Operation

A high-pressure water jet device generates a powerful impact force to flush and clean the inner surface of the hydraulic tube.

Features

This method offers high cleaning efficiency and minimal damage to the hydraulic tube.

Application

High-Pressure water jet cleaning is suitable for hydraulic tubes of various specifications.

4. Oil circulation flushing

Operation

After the hydraulic system is assembled, use a dedicated flushing oil or standby hydraulic oil to circulate through the pipes at high speed using an external flushing pump to remove and filter impurities.

Advantages

This method complies with mainstream standards in the hydraulic industry.

Application

Oil circulation flushing is a common method for cleaning the hydraulic tubes of high-end equipment.

Precautions for Hydraulic Steel Tube Cleaning

1. Pre-purge

Before cleaning, the hydraulic tubes should be pre-purged to remove large particles of impurities.

2. Checking oil cleanliness

During the cleaning process, check the oil cleanliness regularly until it meets the standard.

3. Preventing secondary contamination

After cleaning, seal the hydraulic tube openings immediately to prevent secondary contamination.

4. Secondary flush

For newly installed systems, a secondary flush (after installation and before commissioning) is recommended to ensure thorough cleaning of the pipes.

FAQ

1. How often should hydraulic steel tubes be cleaned?

Under normal circumstances, maintenance cleaning is performed every 6–12 months.

If operating conditions are severe or the oil is severely contaminated, the cleaning interval should be shortened.

2. How do I determine if hydraulic tubes need cleaning?

The following indicators are primarily used:

Hydraulic oil cleanliness exceeds the ISO 4406 standard limit;

The system experiences problems such as valve sticking, pressure fluctuations, and abnormal noise;

Excessive metal particles and impurities are detected during oil analysis.

3. How can I verify the cleaning effectiveness of hydraulic tubes after cleaning?

Use an oil particle counter to test oil cleanliness. Compare to standards such as ISO 4406 or NAS 1638 to ensure that equipment requirements are met (e.g., common standards 18/16/13).

Summary

In summary, cleaning the inside of hydraulic tubes is a crucial step in hydraulic system maintenance that cannot be overlooked. By selecting appropriate cleaning methods and implementing cleaning measures regularly, you can ensure the proper operation and service life of the hydraulic system, providing strong support for industrial production and equipment operation.

Read more: Pipeline cleaning method for seamless hydraulic tubes