Joint types and welding positions

A weld is only as good as the preparation of the joint it is laid in. The joint type and joint preparation determine how the welding wire can penetrate and bind the material together, and the welding position determines how difficult the work is to perform.

§Common joint types

The joint type describes how the parts lie in relation to each other. The most common are butt joints, where two plates or pipes meet edge to edge, and edge joints, often in the form of a fillet weld, where the parts meet at an angle — for example a T-joint or corner joint.

• 01Stucco assembly: the items meet edge to edge
• 02T-joint: one component stands perpendicular to another
• 03Corner joint: the items meet in a corner
• 04Overlap joint: the parts lie partially on top of each other

§Joint preparation

With thicker material it is often necessary to prepare the edges so the weld can penetrate completely. This can be grinding or cutting a chamfer on the edge so a V or X groove is formed and adjusting a suitable root gap between the workpieces. The preparation ensures good fusion in the root of the weld.

§Welding positions

The welding position describes the orientation of the workpiece and the weld seam in space. Welding horizontally downward is easiest because the molten metal pool lies nicely. Vertical and overhead are harder because gravity pulls on the molten metal. The positions have standardized designations used in both training and certification.

Typical postures

• 01Horizontal downward: the melt pool lies calmly, easiest to weld
• 02Horizontal on vertical surface: requires control of the pool
• 03Vertical: can be welded up or down with different techniques
• 04Over the head: the hardest requires good craftsmanship

§Context with certification

Both weld type and welding position are included in what a welding certification is valid for. A test in one position and joint type does not necessarily cover all others. That's why training is done consciously in the positions and weld types that the work and test require.

§Practice in difficult positions

Horizontal positions are learned quickly but vertical and overhead positions require more training. Mastering them makes the welder versatile and able to perform welds where the object cannot be turned to the easy position.