The four recognised positions of welding are: Flat or downhand, horizontal, vertical and over­head. They are shown in Fig. 8.20. The four sketches on the left refer to fillet welds made in the joints, while the four sketches on the right refer to butt welds. The angle and direction in which the electrode is held is also indicated in each case.

Definitions of welding positions are not as simple as they appear to be. They involve the terms ‘weld slope’ and ‘weld rotation’. Weld slope is defined as the angle between the line of the root of a weld and the horizontal. It is shown in Fig. 8.21.

Weld rotate is defined as the angle between the upper portion of the vertical reference plane passing through the line of a weld root, and a line drawn through the same root inter­secting the weld surface at a point equidistant from either toe of the weld. It is illustrated in Fig. 8.22.

L.

Rotation of weld 90°

Rotation ofweld 180°

Fig. 8.22 Diagrams to show weld rotation The welding position are defined as follows:

- Downhand or flat: A position in which the slope does not exceed 10° and the weld rotation does not exceed 10°.

- Inclined: A position in which the weld slope exceeds 10° but not 45° and in which the weld rotation does not exceed 90°.

- Horizontal-Vertical: A position in which the weld slope does not exceed 10°, and the weld rotation is greater than 10°, but does not exceed 90°.

- Vertical: Any position in which the weld slope exceeds 45° and the weld rotation is greater than 90°.

- Overhead: A position in which the weld slope does not exceed 45° and the weld rotation is greater than 90°.

8.6 SUMMARY CHART

A summary chart showing typical preparations for a range of material thicknesses for major arc welding processes has been provided for quick reference on page 165.

The illustrations given do not cover all possible joints which may be used in practice but the principles have been clarified to help the designer choose the best preparations for the constraints of the choices he has at his disposal.