While it’s hard to judge the quality of a weld just by looking at it, appearance provides some clues as to the overall skill of the person who made it. This blog explores what to look for in a weld bead, so the reader can get a feeling for how well it was made. The intention is to equip the reader with enough knowledge to evaluate the quality of the work coming from their preferred fabrication shop, or to help with choosing a shop to partner with.

Welding in Fabrication

Welding is used to fuse separate metal pieces into a single unit. It produces stronger joints than fasteners, and unlike bolted connections, a weld cannot easily be unwelded.

Along with sawing, welding is one of the most widely used processes in fabrication. Welding creates complex decorative and load-bearing shapes and structures of every size and shape imaginable. For many applications, weld quality and strength are essential for the integrity of the fabrication and its safe and durable operation.

Much of the pipework used in fluid handling systems is welded, and in this case, weld quality is critical to prevent leaks while also resisting high and low temperatures and pressures. Additional challenges are that the joint is only accessible from one side, and the need to avoid having the weld project into the fluid flow.

Butt welds and fillet welds comprise the majority of welds made in fabrication. These terms refer to the arrangement of the metal pieces. In a butt weld pieces are welded when butted up together in the same plane. In a fillet weld the join is at an angle, usually 90° or close to.

In both fillet and butt welds the surfaces being joined are prepared by grinding an angle in the faces. When the pieces are brought together – a process known as fit-up – these angles form a channel. The welder makes the weld by using the heat from the torch to locally melt these two faces, while simultaneously feeding in filler wire.

Weld Bead Basics

A weld bead is a rib or fillet formed when two pieces of metal are welded together. It results from the additional filler metal added to ensure good fusion and strength. On a butt joint, the bead will be raised above the surface. In a fillet joint, the bead will be flat at 45° or slightly convex.

The appearance of a weld bead doesn’t provide any information about how well the two pieces of metal have been fused. There could be internal defects like cracks or porosity that reduce joint strength, or very little fusion might have occurred. However, a well-formed weld bead implies the welder knew what they were doing, and so provides some confidence in the quality of the joint produced.

Characteristics of a Quality Weld Bead

How do you recognize a good weld bead? The following list details what to look for:

  • Straightness: The bead should follow the edges being joined without wandering from side to side.
  • Uniformity: A good bead will have a consistent width along its length, and there won’t be any gaps. A fillet weld will be centered between the pieces of metal rather than covering more of one and less of the other. (This type of flaw is called “asymmetry.)
  • Smooth toe transition: This is the line where the sides of the bead meet the workpiece material. The bead should flow into the workpiece and not have steep, even near vertical, sides. (This would mean the weld bead is higher than it needs to be.)
  • Smooth contour: The profile will be slightly convex, with minimal variation along the bead length. (Note that a weave pattern is acceptable, and even desired in some applications.)
  • Minimal spatter: The area around the weld should be clean and free from droplets of weld material. This shows the welder had the wire feed and voltage settings in the optimal range.
  • No defects: If cracks or pinholes are visible on the surface it’s almost certain there will be more inside the weld.
  • Proper penetration: In the case of a butt weld, the weld should extend completely through the material, but not beyond. (When welding pipe this would disrupt the fluid flow.) In a fillet weld penetration can’t be assessed without sectioning the workpiece.
  • No undercutting: If present, this will be seen along the toe or bead edges. It’s where the bead does not fill the groove formed during weld preparation and fit-up, and suggests a lack of strength.
  • Even ripple pattern: When bridging gaps or creating a satisfying aesthetic appearance, many welders like to “weave” the torch from side to side while traversing the length of the weld. This produces a series of ripples along the bead that may, depending on how the torch was moved, even look like a line of overlapping coins. If the weld was made this way the ripple should be consistent along the bead.

Defective or Expensive?

Not every problem with a weld bead necessarily means the weld lacks strength. It may just indicate that the welder was not following best practices or working as efficiently as possible. This is seen when the bead is larger than it needs to be. Adding additional filler doesn’t increase the strength of the weld, but consumes more filler than required and increases the time needed for the task.

Welder Certification

If you’re buying a welded fabrication you want to know it will have the strength needed for the intended application. You’d also like it to be visually appealing, or at least, not unsightly.

The easiest way of meeting these goals is to partner with a fabrication shop where the welders are certified to American Welding Society (AWS) standards. This shows they’ve received training in the principles of welding, and that their skills have been examined and verified by independent experts.

Choose a fabrication Shop With Professional Welders

At Wiley, our welders are both highly experienced and AWS-certified. That means you can have confidence in the integrity of the welded fabrications we produce.

If you need a reliable source for quality metal fabrication work, we’d like to help. Contact us to discuss your project, application, or need.