ARC MAGAZINE

Choosing Between Vertical Up and Vertical Down

Welding in the vertical position can be accomplished in two ways, vertical up, where the welding starts at the bottom of the plate and progresses upward to the top, or vertical down, where the welding starts at the top of the plate and progresses downward. There are a number of factors to consider when determining which direction to travel for a particular job.

It’s important to remember that it’s the position of the weldment that’s vertical, and the progression of the weld that’s up or down. The appropriate progression depends on the type and thickness of the material, as well as the type and size of the electrode.

One consideration is working to a particular code. A welder would be required to weld in the progression specified for that code. For example, most vertical welding done to the AWS D1.1 Structural Steel code would require that welders train and qualify to make vertical welds in the upward progression. Welders who work to other codes, such as those relating to sheet metal or cross country pipelines, may be trained, qualified and required to weld in the vertical down progression.

Another consideration would be when a welder is following a welding procedure specification (WPS). A WPS is a formal written document describing a welding procedure that a welder is required to follow to help assure that quality welds are accomplished when working to a particular code or manufacturer's quality standard.

In the absence of a code or WPS, the welder will most likely make the decision based on several guidelines.

When vertical welding sheet metal-thickness material, usually defined as less than ¼-inch thick, the downward progression of travel is usually beneficial. The faster weld travel speed utilized in vertical down welding allows for lower heat input, smaller weld sizes and less penetration, reducing burn through and distortion. Also, the high travel speeds utilized in the vertical down welding technique may allow the use of higher current and improved production on sheet metal and pipeline applications.

On the other hand, welding vertical on plate or structural steel that is thicker than ¼ inch is usually best accomplished in the vertical up progression. This technique requires somewhat lower current and travel speed than what is used when progressing vertical down. The slower travel speed and techniques utilized in vertical up welding promote higher heat input, slower cooling rate, generally better penetration and larger weld deposits. The flat-to-slightly convex weld profiles made in this manner are less prone to cracking on thicker restrained material.

Keep in mind that some electrodes may not operate satisfactorily for vertical down welding. For example, shielded metal arc welding with a 7018-type electrode (according to the AWS numbering system), while a good choice for welding heavier plate in the vertical up position, is usually not recommended for vertical down welding and, therefore, not a good choice for welding thin materials. A better choice for welding vertical down would be a 6010-, 6011- or 6013-type electrode, all which operate well for either vertical up or down progression.

When it comes to stick welding, the question often arises as to which progression is better, vertical down (left) or vertical up? While one is not necessarily better than the other, choosing the correct progression for the weldment is important.