What are the essentials when welding straight seam steel pipes

Posted by chase Liu on June 20th, 2023

Straight seam steel pipe is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. It is usually divided into metric electric welded steel pipe (ERW pipe), electric welded thin-walled pipe, straight seam submerged arc welded pipe (LSAW pipe) and so on. The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid. The strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe. It can produce welded steel pipes with larger diameters with narrower blanks, and welded pipes with different diameters can also be produced with the same width of blanks. But compared with the straight seam pipe of the same length, the weld length is increased by 30~100%, and the production speed is lower.

When welding straight seam steel pipes, several essentials should be considered to ensure a successful and high-quality weld. Here are the key factors to keep in mind:

1.Proper Joint Preparation:
Ensure accurate alignment and fit-up of the pipe edges to be welded. The edges should be clean, free from contaminants, and properly beveled or prepared according to the welding procedure requirements.

2.Welding Method Selection:
Choose the appropriate welding method for straight seam steel pipes. Common methods include gas metal arc welding (GMAW), gas tungsten arc welding (GTAW), submerged arc welding (SAW), or flux-cored arc welding (FCAW). Select the method that suits the pipe material, thickness, and intended application.

3.Welding Procedure Specification (WPS):
Develop a comprehensive welding procedure specification (WPS) that includes parameters such as welding process, joint preparation, welding position, filler material, preheat/post-weld heat treatment (if applicable), and other relevant details. Adhere to the WPS to maintain consistency and quality in the welding process.

4.Proper Welding Equipment and Setup:
Ensure the welding equipment is in good working condition, properly calibrated, and suitable for the chosen welding process. Use appropriate welding machines, power sources, welding torches, and wire feeders. Set up the equipment according to the manufacturer's guidelines and welding procedure requirements.

5.Shielding Gas and Flux Selection:
Choose the correct shielding gas or flux for the welding process. The choice depends on the welding method and the type of material being welded. The shielding gas or flux helps protect the weld pool from atmospheric contamination, ensuring a sound weld.

6.Welding Parameters:
Control welding parameters, including current, voltage, travel speed, wire feed speed, and arc length, according to the WPS and the specific requirements of the straight seam steel pipe being welded. Maintain proper heat input to achieve good penetration and fusion while avoiding overheating or distortion.

7.Welder Skill and Technique:
Employ skilled welders who are experienced in welding straight seam steel pipes. Proper technique, including maintaining a stable arc, consistent travel speed, and suitable electrode manipulation, is crucial for achieving high-quality welds.

8.Post-Weld Inspection and Testing:
After welding, conduct post-weld inspections to ensure the quality and integrity of the welds. Visual inspection, non-destructive testing (NDT) methods like ultrasonic testing or radiographic testing, and destructive testing (if required) can be performed to assess the weld's soundness and meet specified acceptance criteria.

9.Quality Control and Documentation:
Implement a robust quality control system to monitor the entire welding process. Document all essential parameters, inspections, and tests to ensure traceability, accountability, and compliance with applicable standards and codes.

By considering these essentials and following industry best practices, you can achieve strong, durable, and defect-free welds in straight seam steel pipes.