Common problems and solutions during pre-welding of LSAW steel pipes

In the production of LSAW (Longitudinal Submerged Arc Welded) steel pipes, pre-welding is a critical stage that sets the foundation for the overall weld quality. During this process, various challenges can arise, which can affect the quality, strength, and integrity of the final pipe. These issues may lead to increased production costs, delays, or even the need to scrap the product if not addressed properly. Understanding and identifying common problems during pre-welding, as well as implementing effective solutions, is essential to maintaining the efficiency and quality of the welding process.

Here are some of the common problems encountered during pre-welding of LSAW steel pipes and their solutions:

1) Wrong Side
Problem:
Misalignment of the steel pipe during pre-welding, where the wrong side is positioned, is a common issue that can lead to out-of-tolerance seams, resulting in defects or scrapping of the LSAW (Longitudinal Submerged Arc Welded) steel pipes.

Solution:
To prevent this, strict control should be implemented over the amount of misalignment during pre-welding. This can be achieved by:

Properly aligning the pipe with the welding line.

Ensuring that the positioning equipment is calibrated correctly.

Conducting regular checks for alignment before proceeding to the welding stage.

2) Welding on the Back and Burn-Through
Problem:
Welding on the back, which occurs when the welding bead affects the backside of the pipe, can lead to burn-through. This is a serious issue as it can compromise the quality of the internal and external welds.

Solution:

Monitor the welding parameters to ensure correct heat input and penetration.

Use proper welding techniques and adjust the heat and speed settings to avoid excessive penetration.

Regularly inspect the welded pipe for any defects during the pre-welding stage to catch problems early.

If burn-through occurs, it should be filled and re-welded carefully to ensure the integrity of the pipe.

3) Porosity
Problem:
Porosity is the presence of gas bubbles or voids in the weld, leading to internal defects that can weaken the weld. This typically occurs when the weld is not shielded properly, causing contamination or improper welding conditions.

Solution:

Ensure that the quality of the shielding gas is up to standard, with no moisture or impurities.

Check that the shielding gas pressure and flow rate are correct.

Make sure the welding area is free of rust, oil, and other contaminants that could affect weld quality.

Conduct regular inspections to detect and correct any porosity before moving forward with welding.

4) Poor Weld Formation
Problem:
A poorly formed weld can affect subsequent internal and external welding operations, reducing process stability and welding quality. Poor weld formation is often linked to incorrect welding parameters, such as high welding speed or insufficient heat input.

Solution:

Carefully adjust the welding current, arc voltage, and speed to ensure optimal penetration and consistent weld formation.

If welding speed increases, the weld penetration and width may decrease, leading to poor formation. Maintain a balance between these factors.

Regularly monitor the weld bead during the pre-welding phase to ensure proper formation.

5) Splash
Problem:
Welding splash can burn the surface or groove of the LSAW pipe, affecting both the appearance and the quality of the weld. The cause of splash is often linked to incorrect shielding gas composition or improper welding process parameters.

Solution:

Adjust the proportion of argon in the shielding gas to ensure optimal arc stability.

Fine-tune welding parameters such as voltage, current, and welding speed to reduce excessive splash.

Implement post-weld cleaning procedures to remove any excess splash or spatter.