How to Correctly Select PE Electro Fusion Fittings
Improper selection is the root cause of all subsequent problems. Please follow these steps:
1. Confirm the pipe specifications
Nominal Outside Diameter (DN): Ensure that the nominal outside diameter of the fitting matches the nominal outside diameter of the PE pipe you are connecting. For example, a DN110 fitting can only connect to a DN110 pipe. This is a minimum requirement.
SDR (Size of Surface Relative Density): The SDR (or wall thickness grade) of the fitting should be the same as or compatible with the pipe. Different wall thicknesses in pipes with different SDRs can result in poor fusion results. It is generally required that the SDR of the fitting and pipe be the same.
2. Matching Material Grades
PE80 vs. PE100: PE100 is a higher-performance material with better pressure-bearing capacity and stress-cracking resistance. In principle, PE100 fittings can be used to connect PE80 pipe, but the reverse is not recommended (using PE80 fittings with PE100 pipe may become a weak point in the system). Best practice is to maintain consistent material grades.
3. Selecting High-Quality Brands and Suppliers
Complete Certifications: Choose products that comply with national standards (GB/T) or international standards (ISO), and check for certifications from authoritative organizations (such as sanitary permits for water supply).
Brand Reputation: Prioritize brands with a strong market reputation and high visibility, as they offer more reliable raw materials, production processes, and quality control.
Traceability: Authentic fittings clearly display information such as brand, specification, production date, and batch number, facilitating quality traceability.
4. Visual Inspection
Resistance Wires: Check that the resistance wires inside the fittings are aligned neatly, free of bulges, misalignment, or breakage. Appearance: The inner and outer surfaces of the pipe should be smooth, flat, and clean, free of bubbles, obvious scratches, or dents, and have a uniform color.
Injection Molding Quality: No signs of scorching or carbonization, and the gate should be neatly trimmed and level.
Standard Operating Procedure (SOP) for Electro Fusion
Core Principles: Cleaning, Scraping, Alignment, Stabilization, and Cooling.
Preparation:
Equipment: Dedicated electro fusion welding machine (with parameters matching the pipe), scraper (or rotary scraper), pipe cutter, fixture (clamp), and marker.
Environment: Avoid outdoor work in rain, snow, strong winds, or dusty conditions. Insulation measures should be implemented when the ambient temperature drops below -5°C.
Safety Check: Verify that the welding machine is properly grounded and the power supply voltage is stable.
Operational Procedures:
1. Pipe Cutting and Cleaning
Use a dedicated cutter to cut the pipe vertically and flat. The end surface should be flat and free of burrs. Use a clean cotton cloth or paper towel to thoroughly clean the outer surface of the pipe end and the inner surface of the fitting to remove any contaminants such as oil, dirt, and moisture.
2. Scrape the Oxide Layer (The Most Critical Step!)
A layer of oxide will form on the surface of PE pipe when exposed to air. This layer can severely hinder welding and must be completely removed.
Use a special scraping tool to scrape the surface of the pipe in the weld area. The scraping length should be slightly greater than the socket depth of the fitting.
Scraping Standards: The scraped surface should reflect the natural color of the fresh material, free of residual oxide scale, and have a rough surface to facilitate melting.
Note: Do not touch the scraped surface after scraping to prevent re-contamination.
3. Mark the Insertion Depth
Slide the fitting onto the pipe, mark the socket depth line on the pipe with a marker, and then remove the fitting. This mark provides visual assurance that the fitting is properly seated.
4. Assembly and Fixing
Reinsert the scraped pipe into the electro fusion fitting, ensuring the end of the pipe reaches the internal stop on the fitting and that the marking line on the pipe aligns with the fitting end.
Use a fixture (clamp) to secure the two fittings/tubes to be joined, ensuring they do not move or vibrate during the welding and cooling process. Insufficient securing is a common cause of joint failure.
5. Welding
Firmly connect the output plug of the electro fusion welder to the electrode post on the fitting.
Entering Parameters: Enter the welding voltage (V) and welding time (t) marked on the fitting into the welder. Modern welders can usually automatically identify the parameters by simply scanning the barcode on the fitting.
Start Welding: After confirming that the parameters are correct, start the welder. The welding process will proceed automatically. Do not move or vibrate the pipe or interrupt the power supply during this process.
6. Natural Cooling
After the welding time expires, the electro fusion process is complete, but the molten zone will still be hot.
The joint must be allowed to cool naturally to ambient temperature while secured (it is generally recommended that the cooling time be no less than the welding time). Absolutely prohibited: Water-cooling, air-cooling, or applying any external force to the joint during the cooling period. Forced cooling will generate significant internal stress, leading to joint cracking or cracking.
7. Acceptance
After cooling is complete, remove the fixture.
Visual Inspection: Observe the pipe inspection hole to see if there is any molten material protruding (if so, this is normal). Inspect the joint for obvious defects.
Recordset: Record the welding parameters, operator, date, and other information for each joint to ensure quality traceability.
Common Problems and Taboos
Problem 1: Cold/False Welds
Causes: Oxide layer not scraped clean, contamination, moisture, or improper cooling.
Phenomenon: Extremely low joint strength, resulting in pullout or leakage after pressure application.
Problem 2: Overwelding/Carbonization
Causes: Welding voltage is too high, welding time is too long, or input energy is too high.
Phenomenon: Overheating of the resistance wire causes carbonization (blackening) of the PE material, resulting in loss of sealing and joint strength.
Absolute Taboos:
1. Not scraping the oxide layer.
2. Not securing the joint during welding.
3. Forced cooling.
4. Mixing pipes and fittings from different brands/batches (resistance wire values may vary).
5. Welding in humid or contaminated environments.
Best Practices Summary
1. Select the Right Fit: Strictly match the size, material, and brand of pipes and fittings.
2. Scrape Cleanly: Thoroughly scraping the oxide layer is paramount for successful welding.
3. Securement: Use a clamp to securely secure the joint during welding and cooling.
4. Cool Through: Patiently allow the joint to cool naturally; do not rush.
5. Training: Operators must receive professional training and hold certification.
6. Recordkeeping: Keep records of welding data for every joint for traceability and analysis.
By following the above guidelines, you can significantly improve the success rate and reliability of PE electrofusion pipe fitting connections, laying a solid foundation for the long-term, safe operation of the pipeline system. For critical projects, it is recommended to conduct sample welding and destructive testing (such as tensile and tear tests) before construction to verify the correct process parameters.
Conclusion
Modern water supply and drainage systems demand pipes that combine strength, safety, and durability. Selecting the right pipeline solution depends on critical factors such as application environment, pressure ratings, longevity, and overall cost-effectiveness.
As a trusted manufacturer, HAILI Pipeline provides high-quality plastic piping systems engineered for long service life and dependable performance. From municipal infrastructure to residential applications, our products are designed to ensure secure, efficient, and leak-free water delivery. Explore our wide product range on our website, and feel free to contact us for expert guidance on installation and project solutions. With HAILI Pipeline, reliability flows from the source.
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