What is the welding progression for structural steel typically?

In structural welding, the preferred welding progression is vertical up. This approach is often used for several reasons:

1. Gravity Assistance: When welding vertically upward, the molten weld metal actually moves against the force of gravity, which helps in creating a more controlled and uniform weld bead. This results in better penetration and increased strength of the weld.

2. Heat Control: Welding in the vertical up position allows for better control of the thermal cycle in the material being welded. It helps to minimize the overheating of the surrounding areas, which can reduce the risk of warping or other heat-induced deformations.

3. Quality of the Weld: Vertical up welding generally improves the characteristics of the finished weld as it encourages better fusion and helps in reducing the likelihood of defects such as slag inclusions or porosity.

4. Applications: Vertical up progression is particularly favorable for thicker materials or in situations where a strong vertical joint is necessary.

The other options may represent valid welding techniques, but they do not provide the same benefits in terms of weld quality and structural integrity as vertical up does. For these reasons, vertical up is commonly considered the standard progression for structural steel welding.