IUSA Copper Tube System Installation and Troubleshooting Guide

IUSA Copper Tube System Installation and Troubleshooting Guide

IUSA Cambridge Lee is a leading global copper tube manufacturer, with products covering refrigeration air conditioning (ACR) pipes, water pipes (Type L/K/M), and medical gas pipes. Copper pipes are widely used in HVAC, water supply and drainage, fire protection, medical gas supply and other fields due to their excellent thermal conductivity, corrosion resistance and processability. However, improper selection, installation, or maintenance can lead to leakage, blockage, corrosion, and even system failure. This article is based on the IUSA copper tube product technical manual and combines practical application experience to compile a set of fault diagnosis and prevention guidelines suitable for on-site engineers.

Overview of Product Series and Key Selection Points

2.1 ACR Standard Pipe (ASTM B280)

Features: Degreasing, dehydration, nitrogen filling and covering to prevent internal oxidation. Suitable for air conditioning refrigeration and freezing equipment.

Common faults: Residual oil or oxide in the pipe can cause blockage of the throttle valve and damage to the compressor.

Selection tip: Be sure to confirm that the pipe end cap is intact and undamaged, and avoid opening the original packaging before installation.

2.2 ACR Perform Pipe (ASTM B743)

Features: Higher hardness options (H58, O50, O60), suitable for occasions that require higher mechanical strength.

Common malfunction: Cracks occur during bending, especially in the hard state (H58) and when the radius is too small.

Selection tip: Choose the appropriate annealing state based on the bending radius (soft O60 is suitable for large curvature bending).

2.3 ACR Eco Tube

Features: Economical soft copper tube, nitrogen protection, suitable for ordinary refrigeration and air conditioning pipelines.

Common faults: Thin wall thickness (such as 1/4 "wall thickness of only 0.51mm), susceptible to external force flattening or corrosion perforation.

Selection tip: In vibration or corrosive environments, thicker walled ACR Standard or Perform series should be selected.

2.4 Water Pipe Series (Type L, K, M, ASTM B88)

Type K: thickest wall, high pressure resistance, suitable for underground pipelines, fire protection, and high-voltage systems.

Type L: Medium wall thickness, most commonly used (blue label), suitable for general water supply and hot water.

Type M: thinnest wall (marked in red), suitable for low-pressure indoor water supply.

Common faults: Insufficient wall thickness selection leads to long-term pressure rupture or corrosion perforation.

Selection tip: Type K is preferred for buried or humid environments; Use an L-shaped hot water circulation system and pay attention to expansion compensation.

2.5 Medical Gas Tube (ASTM B819, Type L/K Clean Degreasing)

Features: Strict cleanliness requirements, compliant with CGA G4.1 and NFPA99. There is no grease or particles inside the tube.

Common malfunction: Introducing pollutants during installation, resulting in a decrease in medical gas purity or valve jamming.

Selection tip: Special cutting tools must be used and the end caps must be kept closed before installation.

Common fault phenomena and cause analysis

3.1 Leakage of brazed joints

Phenomenon: When the system maintains pressure, the pressure drops and there are visible moisture or bubbles at the welding site.

Possible reasons:

Unclean pipe ends or fittings, with oxides or grease obstructing the flow of solder.

Uneven heating and incomplete penetration of solder.

Using unqualified brazing or soldering materials (containing corrosive components).

The clearance between the pipe diameters is too large or too small.

Troubleshooting steps:

Use soap water or an electronic leak detector to confirm the leak point.

Cut open the leakage joint for observation: If the solder only forms rounded corners on the surface and the interior is not filled, it indicates insufficient heating or low solder volume.

Check whether the cutting of the pipe end is smooth and whether the deburring is thorough.

3.2 Internal blockage (refrigeration system)

Phenomenon: High exhaust temperature of compressor, ice blockage or dirty blockage of expansion valve.

Possible reasons:

During brazing, nitrogen protection was not used, resulting in the detachment of oxide scale (black copper) on the inner wall of the tube.

Residual moisture, oil stains, or metal shavings inside the pipeline.

During storage or installation, the pipe end is not sealed and dust or moisture enters.

Troubleshooting steps:

Open the pipeline and check the color of the inner wall - black or green oxide layer indicates high-temperature oxidation.

Wipe the inner wall of the tube with a white cloth. If there is black powder or oil stain, it needs to be thoroughly cleaned or replaced.

Confirm whether nitrogen gas (flow rate 0.5-1.0 m ³/h) is continuously introduced during installation and maintained at a slight positive pressure.

3.3 Cracking or flattening of bent parts

Phenomenon: Leakage of refrigerant and decrease in flow rate.

Possible reasons:

Use hard (H58) copper tube for small radius bending.

Failure to use a pipe bender during bending resulted in wrinkles or cracks due to manual bending.

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.

The circulating water system should control the pH value between 7.0 and 8.5, with chloride ions ≤ 200 ppm.

5.6 Regular testing

The refrigeration system undergoes an annual nitrogen pressure test and records pressure changes.

Medical gas pipelines should be wiped and sampled with white silk cloth every six months to check their cleanliness.

Regularly measure the flow rate, pressure, and water quality of the water pipe system.

Suggestions for on-site emergency response

Small aperture leakage: A compression type repair joint can be used (pressure rating needs to be confirmed), but it is best to replace the entire section.

Internal blockage: If the blockage is soft (grease, moisture), high-pressure blowing or specialized cleaning agents can be used; If it is hard oxide skin, the pipe section must be replaced.

Corrosion perforation: Replace the corrosion section while inspecting and eliminating the corrosion source (such as grounding current, chemical medium).

Bending crack: Cut off the crack segment, connect it with a direct joint, and increase the radius or use a soft tube when re bending.