Appropriate welding temperature for straight seam steel pipes

The appropriate temperature for welding straight seam steel pipes depends on various factors, including the type of steel, the welding process, and the specific application requirements. Here are some general guidelines for different welding processes commonly used for LSAW steel pipes.

1. Electric Resistance Welding (ERW)

Temperature Range: 1100°C to 1300°C (2012°F to 2372°F)

Process: The steel strip edges are heated to the welding temperature by electric resistance and then pressed together to form the seam.

2. Submerged Arc Welding (SAW)

Temperature Range: 1200°C to 1600°C (2192°F to 2912°F)

Process: An arc is formed between the electrode and the workpiece, submerged under a layer of flux. The heat melts the edges of the steel pipe, which are then fused together.

3. High-Frequency Induction Welding (HFIW)

Temperature Range: 1400°C to 1600°C (2552°F to 2912°F)

Process: High-frequency current generates heat at the edges of the steel strip, which are then pressed together to form a weld.

4. Manual and Semi-Automatic Welding (e.g., MIG, TIG)

Temperature Range: Varies depending on the specific welding method and steel type

MIG Welding:

Typically operates at temperatures around 1500°C to 1600°C (2732°F to 2912°F)

TIG Welding:

Generally requires temperatures in the range of 1400°C to 1600°C (2552°F to 2912°F)

Factors Affecting Welding Temperature

- Steel Grade:Different grades of steel have varying melting points and thermal properties. The welding temperature must be suitable for the specific steel grade being welded.

- Thickness of the Pipe: Thicker pipes may require higher temperatures to ensure proper fusion of the seam.

- Welding Speed: The speed of the welding process can affect the required temperature. Faster welding speeds might require higher temperatures.

- Welding Environment:Ambient temperature and environmental conditions can influence the welding temperature settings.

Preheating and Post-Weld Heat Treatment (PWHT)

Preheating: Some steel types, especially those with high carbon content, may require preheating to prevent cracking. The preheat temperature typically ranges from 100°C to 300°C (212°F to 572°F) depending on the steel composition.

PWHT: Post-weld heat treatment may be necessary to relieve residual stresses and improve the weld's mechanical properties. The PWHT temperature and duration depend on the specific steel grade and application requirements.

While the exact welding temperature for straight seam steel pipes can vary, adhering to the guidelines for the chosen welding process and considering the specific factors mentioned will help achieve a strong and reliable weld. Always refer to the welding procedure specifications (WPS) and standards relevant to the specific application and material.