IUSA Copper Tube System Installation and Troubleshooting Guide

Copper pipes become brittle and prone to bending and cracking in low-temperature environments (<5 ° C).

Troubleshooting steps:

Check the location and direction of cracks: Cracks along the axial direction of the pipe are mostly caused by excessive bending.

Measure whether the bending radius is greater than the minimum recommended value (usually 3-4 times the outer diameter in soft state).

Check if the roller size of the pipe bender matches the pipe diameter.

3.4 External corrosion and pitting corrosion

Phenomenon: Green or white corrosion products appear on the pipe wall, ultimately leading to perforation and leakage.

Possible reasons:

Contact with corrosive media such as acids, alkalis, and cleaning agents containing ammonia.

During installation, insulation treatment was not carried out, resulting in galvanic corrosion between copper pipes and iron supports.

The water quality contains excessively high levels of chloride ions, especially in circulating cooling water.

Troubleshooting steps:

Use pH test strips or chemical reagents to test the environment and medium inside the tube.

Observation of corrosion morphology: uniform thinning is acidic corrosion; Localized pitting corrosion is caused by chloride ions or galvanic interactions.

For buried copper pipes, check whether the backfill soil contains corrosive substances.

3.5 Medical gas pipeline contamination

Phenomenon: Terminal gas purity alarm, valve malfunction.

Possible reasons:

Oil containing tools or uncleaned chips are used when cutting copper pipes.

During brazing, nitrogen gas was not used for blowing, resulting in oxidation of the inner wall.

When storing, the end cover falls off and inhales dust.

Troubleshooting steps:

Wipe the inner wall of the tube with a white silk cloth and check for oil stains or particles.

Inspect the interior of the pipeline using an endoscope.

Confirm if the installation process complies with NFPA 99 and CGA G4.1 requirements.

Systematic troubleshooting process

When there is an abnormality in the copper pipe system, it is recommended to diagnose it in the following order:

Review completion records: Confirm whether the model, wall thickness, and standards (ASTM B280/B88/B819, etc.) of the copper pipes used meet the design requirements.

Visual inspection: Look for signs of leakage, rust, deformation, or mechanical damage. Pay attention to the color code of the pipe end: blue is L-shaped, green is K-shaped, and red is M-shaped. ACR pipes do not have a unified color code but usually have labels.

Pressure testing: Conduct air or water pressure testing on the system to confirm its pressure holding capacity. Nitrogen is commonly used to maintain pressure in refrigeration pipelines (2.5-4.0 MPa) and observe whether the pressure drops.

Cleaning and analysis: Cut off the suspicious pipe section and check the cleanliness of the inner wall. If oxide scale is found, it is necessary to check the historical welding process records.

Material verification: If there is suspicion of defects in the pipe itself, chemical composition and mechanical properties can be inspected and compared to ASTM standards.

Preventive maintenance and correct practices

5.1 Storage and Handling

Copper pipes should be stored indoors in a dry, ventilated, and acid free environment. Avoid direct contact with cement floors (which are prone to moisture absorption).

The floppy disk tube should not be heavily pressed or stepped on to prevent deformation.

Before use, check if the end cap is intact. If there is any damage, cut off 50mm of the end before use.

5.2 Cutting and Deburring

Use a specialized pipe cutter (wheel cutter) and do not use saw blades or angle grinders to avoid burrs and metal shavings.

After cutting, it is necessary to use a reamer or round file to remove internal and external burrs to avoid increased flow resistance or solder adsorption of impurities.

5.3 Key points of brazing process

Nitrogen protection: During the brazing process, nitrogen gas (flow rate 0.5-1.0 m ³/h) must be continuously introduced into the tube until the joint cools down to below 100 ° C. This can prevent oxidation of the inner wall.

Solder and flux: Silver based or phosphor copper solder should be used, and the flux should be suitable for copper pipes and have no corrosive residue.

Heating sequence: Preheat the pipe fittings evenly first, then heat the joint between the pipes and fittings to allow the solder to be sucked in by capillary action.

Cooling after welding: Natural cooling, do not use water for rapid cooling to avoid cracking.

5.4 Bending operation

Soft copper pipes (O60) can be bent using spring benders or manual benders; The hard copper tube (H58) should be bent using a hydraulic pipe bending machine, and the bending radius should not be less than 5 times the outer diameter.

Fill the tube with dry sand and seal both ends before bending to prevent wrinkling (used for small radius bending).

5.5 Anti corrosion measures

When copper pipes come into contact with dissimilar metals (iron, aluminum), insulation pads or plastic sleeves should be added.

Buried copper pipes should be coated with asphalt or polyethylene anti-corrosion coating and wrapped with anti-corrosion tape.