Hardness of ERW steel pipe

Welding ERW (Electric Resistance Welded) pipes during winter necessitates specific precautions to ensure quality and avoid defects due to cold temperatures. Follow these steps for optimal results.

1. Adjust Welding Parameters

Increase Welding Current: Raise the welding current to achieve deeper penetration.

Reduce Welding Speed: Slow down the welding speed to allow better fusion.

Increase Weld Cross-Sectional Area: Increase the cross-sectional area and length of the weld if necessary.

Preheating: Preheat the workpiece to reduce the risk of cracking.

2. Proper Arc Management

Avoid External Groove Starts: Do not start the arc outside the groove on the base metal.

Fill Arc Pits: Ensure that the arc extinction pit is completely filled to prevent weak spots.

3. Minimize Cold Temperature Operations

Avoid Low-Temperature Bending and Assembly: Refrain from bending, correcting, and assembling weldments under low-temperature conditions whenever possible.

4. Maintain Interlayer Temperature

Preheat and Monitor Temperature: Preheat the material before welding and strictly maintain the interlayer temperature throughout the process. The interlayer temperature should not fall below the preheating temperature.

5. Use Appropriate Welding Materials

Low Hydrogen Materials: Utilize low hydrogen or ultra-low hydrogen welding materials to reduce the risk of hydrogen-induced cracking.

6. Continuous Welding

Avoid Interruptions: Complete the entire weld without interruption to prevent weak spots and ensure uniformity.

7. Expanded Recommendations for Winter Welding

- Preheating Techniques

Uniform Preheating: Use uniform preheating methods such as heating blankets or induction heating to ensure even temperature distribution.

Preheating Temperature: Typically, preheating temperatures range from 50°C to 200°C, depending on the material and thickness of the pipe.

- Post-Weld Heat Treatment (PWHT)

Stress Relief: After welding, apply post-weld heat treatment to relieve residual stresses and improve the ductility of the weld.

- Environmental Controls

Welding Enclosures: Set up temporary enclosures around the welding area to shield it from wind and extreme cold.

Heat Sources: Use portable heaters to maintain a consistent ambient temperature around the welding site.

8. Inspection and Testing

Non-Destructive Testing (NDT): Perform ultrasonic testing, X-ray inspection, or magnetic particle inspection to detect any weld defects.

Visual Inspection: Conduct thorough visual inspections before and after welding to identify potential issues.

Conclusion

Welding ERW pipes in winter requires careful adjustments to welding parameters, proper arc management, and effective preheating techniques. Maintaining appropriate interlayer temperatures and using low hydrogen materials minimizes the risk of defects. Continuous welding without interruptions and post-weld heat treatment further enhance weld quality. By following these steps, ERW pipes welded in cold conditions can meet the highest standards of quality and performance.