Cylinder Common Welding Problems

When weld defects form in a weld they can weaken the joint. In some cases, this results in complete failure of the weldment. These are classified according to ISO 6520. Blow documents are collected from the welding blog.

Cracks

These cracks weaken a weld, and even worse, cracks tend to grow at a rapid rate making the problem worse. There are three main types of cracks:

1. Longitudinal cracks run along, or are parallel, to the length of the weld.

2. Transverse cracks run across the width of a bead.

3. Crater cracks usually occur at the end of a weld when the arc is terminated. They are often star-shaped and form when a dent or “crater” is formed at the end of a weld.

Inclusions

Impurities can become trapped inside a weld, and these are referred to as inclusions. Contaminants trapped inside a weld dramatically weaken the joint.

Lack of Fusion

It may seem obvious, but the filler material must be well bonded to the base metal on both sides and to welds underneath during multiple passes. If there are voids, gaps, or poor adhesion, the joint will be structurally impaired.

Porosity

Weld porosity (also known as wormhole weld) is where gas bubbles accumulate and get trapped inside a weld. This is also said to be porous. A cross-section of a porous weld bead will resemble a sponge with all the air bubbles trapped inside.

Under Cut

When the welding process results in spots or sections being less than the original base metal, the defect is referred to as an undercut. This will often appear as a “notch” at the edge of a weld, either on the top or bottom of the weld.

Poor Penetration

When the bead does not fill a butt joint all the way to the bottom, the weld achieves poor penetration. It is also referred to sometimes as incomplete penetration. Whatever you call it, this form of defect also compromises the integrity of a joint.

Burn Through

If too much heat is applied during the weld, you can actually blow a hole through the metal. This defect is referred to as burn through, but sometimes it is also called melt through. Of course, creating a hole defeats the purpose of a weld and destroys the joint. This type of defect is usually encountered with thin stock, material less than 1/4 inch thick. But it can occur with thicker stock if your welder settings are too high, if the gap between pieces is large, and/or you are moving the torch too slow.

Under Filled

When the weld bead sits below the surface of the base metal, the weld is said to be under-filled. The bead itself is thinner than the base metal, which weakens the joint. This condition often appears as a “rut” that runs the length of the bead and is sometimes called a convex joint.

Excess Reinforcement

In contrast to an underfilled joint, a defect results when there is too much filler material in the joint. This is known as excess reinforcement or a “high” crown. Project specifications and codes often regulate what is considered too high.

Spatter

While usually not a threat to structural integrity, spatter can be considered a defect. The aesthetics of a weld are sometimes as important as the weld’s strength. But nothing makes welded pieces look sloppy, like spatter stuck all over the surrounding metal.

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