Welding Joints and Symbols

Basic terms of a welded joint are shown in Fig. and the five basic types of joints are shown in Fig.

Welding

Various categories of welded joints (welds) are characterized by symbols which, in general are similar to the shape of welds to be made. These symbols are categorized as:

(i) Elementary symbols
(ii) Supplementary symbols
(iii) Combination of elementary and supplementary symbols and
(iv) Combination of elementary symbols.

Types of Joint

 Position of Weld Symbols on Drawing
The complete method of representation of the welds on the drawing comprises, in addition to the symbol (3), the following Fig.

Welding Position

(i) An arrow line (1) per joint,
(ii) A dual reference line, consisting of two parallel lines; one continuous and one dashed (2a, 2b) and
(iii) A certain number of dimensions (4) and conventional signs (3).

NOTE The dashed line may be drawn either above or below the continuous line (Fig.). For symmetrical welds, the dashed line is omitted.

Elementary Welding Symbols

Welding Symbols

Supplementary Welding Symbols

Combination of Elementary and Supplementary Symbols

Welding Symbols Combination

Combination of Elementary and Supplementary Symbols (contd.)

Welding Symbols Combination

Conventional Signs

The two conventional signs used for welding as per BIS are a circle at the elbow (1), connecting the arrow and the reference line to indicate welding all around and, by a filled-in circle (2) at the elbow to indicate welding on site, as shown in Fig. These are shown, in addition to
the weld symbols of the joint to be made.

Conventional Sign

Another convention as per International Standards Organisation, indicates the process of welding. For this, the abbreviation of the welding process is written as a note at the tail end of the arrow, forming a 90°V as shown in Fig. Here, SAW stands for submerged arc welding.

Location of Welds

The location of the welds is specified by the following:

(i) Position of the arrow line,

(ii) Position of the reference line and

(iii) Position of the symbol.

Position of Arrow Line

Position of Arrow LineThe arrow line joins one end of the continuous reference line, such that it forms an angle with it and is completed by an arrow head. Figure shows the relation between the arrow line  and the joint. The terms ‘arrow side’ and ‘other side’ (in case of fillet welding) are used with respect to the continuous plate.

Position of Arrow LineThe position of the arrow line with respect  to the weld is generally of no special significance.

Position of Arrow LineHowever, in the case of edge preparation, the arrow line points towards the plate which is prepared.

Indication of Edge Preparation

.Indication of Edge Preparation

Position of the Reference Line

The reference line shall preferably be drawn parallel to bottom edge of the drawing and if it is not possible; then it is drawn perpendicular.

Position of Symbol

Position of Symbol  The symbol is placed either above or beneath the reference line as per the following regulation: It is placed on the continuous side of the reference line, if the weld (weld face) is on the arrow side of the joint or on the dashed line side, if the weld is on the other side of the joint, as shown in Fig.

Dimensions of Welds

Each weld symbol may be accompanied by a certain number of dimensions. These dimensions are written as indicated in Fig. It shows (i) the main dimensions relative to the cross-section, written on the left hand side of (before) the symbol and (ii) longitudinal dimension written on the right hand side of (after) the symbol. NOTE The absence of any indication following the symbol, signifies that the weld is to
be continuous over the whole length of the work piece.

 Dimensions of WeldsThere are two methods to indicate the dimensions of fillet welds as shown in Fig. The letter a(throat thickness), or z(leg length) is always placed in front of the value of the corresponding dimension.

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