Chapter Twenty-One Welding Representation

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Chapter Twenty-One. Welding Representation

Objectives

After studying the material in this chapter, you should be able to:

1. Describe the various welding processes.

2. Draw the common welding symbols.

3. Dimension a welding drawing using standard ANSI welding notation.

4. Identify and draw a fillet weld, groove weld, back weld, spot weld, seam weld, projection weld, and flash weld.

5. Describe the use of welding symbols in CAD drawings.

Refer to the following standards:

• AWS A2.4 Standard Symbols for Welding, Brazing, and Nondestructive Examination

• AWS A1.1 Metric Practice Guide for the Welding Industry

• AWS A3.0 Standard Welding Terms and Definitions

Photograph shows an automobile frame is welded placed on a robotic automatic assembly line.

An automobile frame is welded on a robotic automobile assembly line. (Courtesy of Vladimir Pcholkin/Stone/Getty Images.)

Overview

For fastening parts together permanently, rather than using bolts, screws, rivets, or other fasteners, welding is often the method of choice. Welding is widely used in fabricating machine parts or other structures that formerly would have been formed by casting or forging. Structural steel frames for buildings, ships, and other structures are often welded. Welding is one of few machine processes that adds material to a work-piece, rather than removing it.

Welding symbols on a mechanical drawing provide precise instructions for the welder. The weld type and the location of each weld must be clearly defined using standardized symbols. CAD libraries of welding symbols can simplify the drawing process. Welding templates can speed the process of drawing by hand.

Understanding Weldment Drawings

Welding is used extensively and for a wide variety of attachment purposes. A series of “Standard Welding Symbols” were developed in 1947 to provide an accurate method of showing the exact types, sizes, and locations of welds on construction drawings of machines or structures. Before these standards were developed, notes on the drawing such as “To be welded throughout” or “To be completely welded,” gave responsibility for welding control to the welding shop. Such instruction was dangerously vague and could be unnecessarily expensive, because shops would often “play it safe” by welding more than necessary.

Welding Processes

The principal methods of welding are

• Gas welding

• Arc welding

• Resistance welding

Gas Welding The oxyacetylene method is generally known as gas welding. Gas welding originated in 1895, when the French chemist Le Châtelier discovered that the combustion of acetylene gas with oxygen produced a flame hot enough to melt metals. This discovery was soon followed by the development of practical methods to produce and transport oxygen and acetylene and the construction of torches and welding rods.

Arc Welding The electric arc method is generally known as arc welding. In arc welding, the heat of an electric arc is used to fuse the metals that are to be welded or cut. Gas metal arc welding (GMAW) is often known by its subtypes metal inert gas welding (MIG) and metal active gas welding (MAG).

Arc welding uses a wire electrode that is fed along with a shielding gas through the welding gun. Gas tungsten arc welding (GTAW), often known as tungsten inert gas welding (TIG), and plasma arc welding are processes that conduct the arc through a heated gas called a plasma to produce strong high-quality welds. Arc and gas welding are important construction processes in industry.

Resistance Welding Electric resistance welding is generally called resistance welding. In resistance welding, two pieces of metal are held together under some pressure, and a large amount of electric current is passed through the parts. The resistance of the metals to the passage of the current causes heat at the junction of the two pieces, resulting in the welding of the metals.

Standard Symbols

The text and illustrations of this chapter are based primarily on ANSI/AWS A2.4, Standard Symbols for Welding, Brazing, and Nondestructive Examination. You may also want to refer to AWS A1.1, Metric Practice Guide for the Welding Industry, and ANSI/AWS A3.0, Standard Welding Terms and Definitions.

Welding drawings are a special type of assembly drawing, as weldments are composed of a number of separate pieces fastened together as a unit. The welds themselves are not drawn but are clearly and completely indicated by the welding symbols. Figure 21.1 shows a drawing using standard welding symbols. Most CAD packages provide standard welding symbols that can quickly be inserted into your drawing.

Image has two pictures labeled a and b, picture a illustrates a welding drawing while picture b shows a practical fillet welding of a structure.

21.1 (a) Portion of a Weldment Drawing and (b) Welded Structure (Photo has been rotated to the same orientation as the drawing in part a.) (Courtesy of Midwest Steel Industries.)

The joints are all shown in the drawing as they would appear before welding. Dimensions are given to show the sizes of the individual pieces to be cut from stock. Each component piece is identified by encircled numbers and by specifications in the parts list.

Understanding a Welding Symbol

A welding symbol added to the drawing has many different features that specify each detail of the weld. The items that can be specified are:

• Type of weld

• Process

• Depth of bevel, size, or strength for some weld types

• Groove weld size

• Finishing designator

• Contour

• Groove angle

• Root opening

• Length of weld

• Number and pitch (center to center spacing) of welds

• Whether the weld is to be field welded (done on site)

• All-around indicator

• Which side of the material is to be welded

That is a lot of information contained in one symbol. The next sections provide more detail about the information contained in the symbol you will add to your drawings. Figure 21.1 shows an example of weld symbols used on a drawing and the actual welded part. Figure 21.2 points out features of a weld to which the symbol may refer.

Image illustrates the features of a weld done joining two rectangular surfaces.

21.2 Features of a Weld

21.1 Types of Welded Joints

There are five basic types of welded joints: butt joint, corner joint, T-joint, lap joint, and edge joint. They are classified according to the positions of the parts being joined. Table 21.1 shows illustrations of the types of welded joints.

Table 21.1 Basic Types of Welded Joints

A number of different types of welds are applicable to each type of joint, depending on the thickness of metal, the strength of joint required, and other considerations.

21.2 Types of Welds

The four types of arc and gas welds are shown in Figure 21.3:

• Back or backing weld

• Fillet weld

• Plug or slot weld

• Groove weld

Collage of 8 different figures labeled from a to h.

The illustration has figures denoting various forms of welding in one row and the corresponding weld symbols below them in another row. The illustrations are as follows. Figure A represents Back or backing, where two slabs are joined by a welding done only as a single layer at the top. The symbol is a half circle. Figure B represents Fillet, where two slabs are placed perpendicular to each other with their edges making an L shape and the welding is done at the inner crook of the L. The symbol is a right-triangle. Figure C represents Plug or Slot, where two rectangular slabs are placed one above the other, such that the slab at the top falls out a bit on the right side. The welding is made on different parts of the slab at the top, in the shapes of circles and a streak. The symbol is a rectangle. Figure D represents Square, where two slabs are placed side by side with a valley-like gap filled with welding material. The symbol is a pair of parallel lines. Figure E represents "V," where the welding is similar to the Square welding, but the valley-like gap is slightly broader in this. The symbol is a wide "V." Figure F represents "Bevel," where the welding is similar to the V and square welding, but the valley-like gap is more inclined on the right. The symbol is character "V" with one arm straight, while the right arm is highly inclined to the left. Figure G represents "U," where the gap between the two slaps is welded in the shape of U, and the valley never touches the bottom of the slabs. The symbol is like a wine glass with no base or root. Figure H represents "J," where the welding is similar to "U," but the sides of the valley are broader on the right and straight on the left. The symbol is a positively sloped line touching a vertical line.

21.3 Basic Welds and Symbols

Groove welds are further classified as square, V, bevel, U, and J, as shown in Figures 21.3d through h.

More than one type of weld may be applied to a single joint. For example, a V weld may be on one side and a back weld on the other side. Frequently, the same type of weld is used on opposite sides, forming such welds as a double-V, a double-U, or a double-J.

The four basic resistance welds are:

• Spot weld

• Projection weld

• Seam weld

• Flash or upset weld

Except for the flash or upset weld, the corresponding symbols for these welds and additional basic weld symbols for surfacing, groove, and flange joints are given in Figure 21.4. (See Section 21.12 for the use of the square groove weld symbol for the flash or upset resistance weld.) Supplementary symbols are shown in Figure 21.5. Depending on your field and the particular project, you may need to use only a simple symbol composed of the minimum elements (the arrow and the weld symbol) or you may need to use the additional components.

Illustration shows 7 different basic weld symbols.

Figure 1 represents Spot or projection. A circle is placed touching the center of a horizontal line. The line is labeled "Reference line." Figure 2 represents Seam. A circle is placed touching the center of the reference line, and two horizontal lines are drawn across the circle. Figure 3 represents Surfacing. Two half circles are placed next to each other, below the reference line, touching each other and the line. Figure 4 and Figure 5 are different models of Groove. Figure 4 is Groove- Flare. Two half arcs are placed on the reference line, facing in opposite directions. Figure 5 is Groove - Flare bevel. A small straight line and a half arc are placed next to each other on the reference line. The small line is perpendicular to the reference line. Figure 6 represents Edge. Three vertical lines joined on the top by a horizontal line is placed on a dashed line. Figure 7 represents Scarf. Two forward slashes, parallel to each other, are placed on a dashed line.

21.4 Additional Basic Weld Symbols

Illustration shows 8 different supplementary weld symbols.

Figure 1 represents Weld all around. A leader line pointing down left with a reference line to its right is shown, with a circle at the elbow of both lines. Figure 2 represents Field Weld. Two sets of leader line (pointing down left) with a reference line to its right are shown. One set has a flagpole symbol facing the right, while the other set has a flagpole symbol facing the left. Both flagpoles are placed at the joint of the lines. Figure 3 represents Melt-thru. A leader line pointing down left with a reference line to its right is shown, and a shaded half-circle is placed below the reference line. Figure 4 represents Consumable insert (square.) A leader line facing down right is shown with a reference line. A square is placed on the reference line. Figure 5 represents Backing or spacer matl. Two sets of leader line (pointing down left) with a reference line to its right are shown. One set has a rectangle placed on the reference line, while another set has a rectangle placed such that it overlaps the center part of the reference line. Figure 6, 7, and 8 are collectively labeled Contour. Figure 6 represents Flush. A leader line pointing down right with a reference line to its right is shown. A small horizontal line is placed parallel to the reference line. Figure 7 represents Convex. A leader line pointing down right with a reference line to its right is shown. An arc is placed above the reference line not touching it, facing downward. Figure 8 represents Concave. A leader line pointing down right with a reference line to its right is shown. An arc is placed above the reference line not touching it, facing upward.

21.5 Supplementary Symbols

21.3 Welding Symbols

The basic element of the symbol is the “bent” arrow, as shown in Figure 21.6a. The arrow points to the joint where the weld is to be made (Figure 21.6b). Attached to the reference line, or shank, of the arrow is the weld symbol for the desired weld. The symbol would be one of those illustrated in Figures 21.3 and 21.4. In this case, a fillet weld symbol has been used.

Illustration of 5 different welding symbols, labeled from a to e.

Figure A has a leader line pointing down right with a reference line to its left. The figures from B to D show graphical illustrations (at the top) and diagrammatic illustrations (at the bottom) of different welding symbols. Figure B has two rectangular blocks placed perpendicular to each other. The left joint of the blocks is shown to be welded. Below this, two rectangular blocks are placed perpendicular to each other. A leader line pointing to the left joint of the blocks has a reference line to its left. A right triangle is placed below the reference line. The triangle is labeled "Vertical side of symbol always on left." Figure C has two rectangular blocks placed perpendicular to each other. The right joint of the blocks is shown to be welded. Below this, two rectangular blocks are placed perpendicular to each other. A leader line pointing to the left joint of the blocks has a reference line to its left. A right triangle is placed above the reference line. Figure D has two rectangular blocks placed perpendicular to each other. The joints on both sides of the blocks are shown to be welded. Below this, two rectangular blocks are placed perpendicular to each other. A leader line pointing to the left joint of the blocks has a reference line to its left. Two right triangles are placed above and below the reference line. Figure E has a leader line pointing down right with a reference line to its left. The reference line has a tail in the shape of V, with the vertex touching the reference line. The length of the reference line is labeled "1.00 approximation by 0.20." The length of the arm of the tail V is labeled "0.20." The angle between the arm of the tail V and the reference line is 45 degrees. The angle between the reference line and the leader line is labeled "30 degrees minimum."

21.6 Welding Symbols

The weld symbol is placed below the reference line if the weld is to be on the arrow side of the joint, as in Figure 21.6b, or above the reference line if the weld is to be on the other side of the joint, as in Figure 21.6c. If the weld is to be on both the arrow side and the other side of the joint, weld symbols are placed on both sides of the reference line (Figure 21.6d). This rule for placement of the weld symbol is followed for all arc or gas weld symbols. Dimensions for creating a weld symbol are shown in Figure 21.6e.

When a joint is represented by a single line on a drawing, as in the top and side views of Figure 21.7b, the arrow side of the joint is regarded as the “near” side to the reader of the drawing, according to the usual conventions of technical drawing.

Illustration of the "Arrow side" and "Other side" with the help of a pictorial representation (figure A) and diagrammatic representation (figure B.)

21.7 Arrow Side and Other Side

For the plug, slot, seam, and projection welding symbols, the arrow points to the outer surface of one of the members at the centerline of the weld. In such cases, the arrow side of the joint is the one to which the arrow points, or the side “near” the reader (see Sections 21.8 and 21.12).

Note that for all fillet or groove symbols, the vertical side of the symbol is always drawn on the left, as shown in Figure 21.6b.

For best results, welding symbols should be drawn using CAD or a template, but in certain cases where necessary, they may be drawn freehand.

The complete welding symbol, enlarged, is shown in Figure 21.8. See Appendix 31 for additional welding symbol details.

Figure illustrates the standard locations of the elements of the welding symbols.

The figure has a leader line pointing down right with a reference line to its left. The reference line has a tail in the shape of V, with vertex touching the reference line. The elbow of the landing and leader lines has a circle, and flagpole facing the left. Along the reference line, a number of characters denoting various elements of the welding symbols, and each of them is labeled. Character "T" is placed to the left of the tail. Character "S" is placed to the right of the tail above the reference line. Character "E" is placed enclosed in parentheses to the right of S. Phrase "Both sides" enclosed in parentheses is placed above and below the line, such that "Both" is below the line and "sides" is above the line. To the left of both the words, two open braces are shown. At the center of the line, character "R" is placed." Above R, characters "F" and "A" are placed like a fraction. To the right of R, phrase "Other side" is placed enclosed in parentheses above the line. Below the line Character "N" is placed enclosed in parentheses. (N and R fall on the same line.) To the right of N, phrase "Arrow side" is placed enclosed in parentheses. Two closed braces are placed, one below the line and one above the line. To the right of the brace above is "L hyphen P." The labeling of the parts is as follows. T - Specification, process, or other reference. V - Tail (omitted when reference is not used.) Reference line - Reference line. Open parentheses - Basic weld symbol or detail reference. S - Depth of preparation; size or strength for certain welds. E - Effective throat. R - Root opening: depth of filling for plug and slot welds. F - Finish symbol. Fraction line - Contour symbol. A - Groove angle; included angle of countersink for plug welds. L - Length of weld. P - Pitch (center to center spacing) of welds. Flagpole - Field weld symbol. Leader line - Arrow connecting reference line to arrow side member of joint. Circle in the elbow - Weld all around symbol. N - Number of spot or projection welds. A line parallel to the reference line is marked and labeled "Elements in this area remain as shown when tail and arrow are reversed."

21.8 The Standard Locations for the Elements of the Welding Symbol

Reference to a specification, process, or other supplementary information is indicated by a symbol in the tail of the arrow (Figure 21.9a). Otherwise, a general note may be placed on the drawing, such as

Illustration of standard locations for the elements of the welding symbol.

Figure A shows a leader line pointing down left with a reference line to its right. The reference line has a V-shaped tail. To the right of tail "AW." The V is labeled tail and the text AW is labeled "Reference symbol." Figure B has two diagrams. The first diagram has a circle enclosed inside a square, with centerline and centermark drawn for the circle. The second diagram has two rectangular blocks, one placed horizontally, and the other placed over it, perpendicularly, with a centerline across the structure. An arrow (leader line with a reference line,) with a circle at the elbow and a right triangle placed below points to the right joint of the structure. Figure C shows a rectangular block placed vertically, with another rectangular block placed perpendicular to the first block. An arrow, with a flagpole at the elbow and a right triangle below the line, points to the left join of the structure.

21.9 The Standard Locations for the Elements of the Welding Symbol

UNLESS OTHERWISE INDICATED, MAKE ALL WELDS PER SPECIFICATION NO. XXX

If no reference is indicated in the symbol, the tail may be omitted.

To avoid repeating the same information on many welding symbols on a drawing, general notes may be used, such as

FILLET WELDS .3125″ UNLESS OTHERWISE INDICATED

ROOT OPENINGS FOR ALL GROOVE WELDS .1875″ UNLESS OTHERWISE INDICATED

Welds extending completely around a joint are indicated by an open circle around the elbow of the arrow (Figure 21.9b). When the weld all around symbol is not used, the welding symbol is understood to apply between abrupt changes in direction of the weld, unless otherwise shown. A short vertical staff with a solid triangular flag at the elbow of the arrow indicates a weld to be made “in the field” (on the site) rather than in the fabrication shop (Figure 21.9c).

Spot, seam, flash, or upset symbols usually do not have arrow-side or other-side significance and are simply centered on the reference line of the arrow (Figures 21.10a through c). Spot and seam symbols are shown on the drawing as indicated in Figures 21.10d and e. Note that the required process must be specified in the tail of the symbol (RSW = resistance spot weld, EBW = electron beam weld).

Illustration of welding symbols representing Spot, Seam, and Flash.

The figure has 5 different diagram labeled A to E. Diagram A representing Spot has an arrow (a leader line with a reference line) pointing top right, with a circle placed at the center of the reference line, and a V tail connected to the ending of reference line. Diagram B representing Seam has an arrow pointing to down left with circle placed at the center of the reference line. Two short horizontal lines are drawn across the circle. A V tail is connected to the end of reference line. Diagram C representing Flash has an arrow pointing to the down left, with two short lines parallel to each other placed at the center of the reference line, and a V tail connected to the end of the reference line. Diagram D and Diagram E represent plan or elevation diagram of a welding. Both have a representation of a piece of the welding material as a rectangular block with edges cut. The block has a dashed line followed by a centerline and a thick horizontal line at the bottom. In diagram D, an arrow, with a circle at the center and a V tail, points to the center line. The distance between the left edge to the point where the arrow points, is measured 1.20. The required process is labeled as RSW next to the V tail. In diagram E, an arrow, with a circle overlapped by two short lines at the center and a V tail, points to the center line. The required process is labeled as EBW next to the V tail.

21.10 Spot, Seam, and Flash Welding Symbols

For bevel or J-groove welds, the arrow should point with a definite change of direction, or break, toward the member that is to be beveled or grooved (Figures 21.11a and b). In this case, the upper member is grooved. The break is omitted if the location of the bevel or groove is obvious.

Illustration provides another set of welding symbols with 8 miniature diagrams, labeled from a to h.

Figure A shows two rectangular blocks placed one above the other and welded at the joint. Figure B shows a side view diagram of the structure in figure A. An arrow (a leader line with a reference line) with a "J" weld symbol on the reference line, points to the welded joint of the structure. Figure C has an arrow with a "V" weld symbol on the reference line. Value 90 degrees is denoted above the V symbol, and value .312 is placed to the left of "V" symbol. Figure D has an arrow with a Fillet symbol placed below the reference line. Value .25 is placed to the left of the fillet symbol, whole value 2 hyphen 5 is placed to the right. Figure E has an arrow with a Fillet symbol placed below the reference line, with value .5 to the left of the symbol, and value 2 hyphen 5 to the right. Figure F shows an arrow with a horizontal reference line connected to an inclined reference line which in turn is connected to a leader line. Two weld symbols, Fillet is placed above the line and Bevel is placed below the line. Figure G has an arrow with "V" weld symbol above the line and Back weld symbol at the bottom. Figure H has an arrow similar to Figure F. Two sets of a fillet and a "J" are shown, one set placed above the line and one set placed below the line.

21.11 Welding Symbols

Lettering for the symbols should be placed to read from the bottom or from the right side of the drawing in accordance with the aligned system (Figures 21.11c through e). Dimensions may be indicated on a drawing in the fractional, decimal-inch, or metric system.

When a joint has more than one weld, the combined symbols are used (Figures 21.11f through h).

21.4 Fillet Welds

The usual fillet weld has equal legs (Figure 21.12a). The size of the weld is the length of one leg, as indicated by a dimension figure (fraction, decimal-inch, or metric) at the left of the weld symbol (Figure 21.12b). For fillet welds on both sides of a joint, the dimensions should be indicated on both sides of the reference line, whether the dimensions are identical or different. (Figure 21.12c). The lengths of the welds and the pitch (center-to-center spacing of welds) are indicated as shown. When the welds on opposite sides are different in size, the sizes are given as shown in Figure 21.12d. If a fillet weld has unequal legs, the weld orientation is shown on the drawing, if necessary, and the lengths of the legs are given in parentheses to the left of the weld symbol, as in Figure 21.12e. If a general note is given on the drawing, such as

ALL FILLET WELDS .3125″ UNLESS OTHERWISE NOTED

Illustration of Dimensions of a Fillet Weld using 5 different diagrams labeled from A to E.

Figure A represents a fillet welding. A rectangular block is placed perpendicularly over a horizontal rectangular block, such that their edges form an L shape. The crook of the L is shown to be welded. The thickness of the welded area is measured as ".5" on both the blocks. Figure B represents a diagram of the structure in Figure A. An arrow with a Fillet symbol below the line points to the welded joint. Value ".5" is placed to the left of the weld symbol. The value is labeled "Size of weld." Figure C has two rectangular blocks placed perpendicular to each other forming an inverted T. An arrow with two Fillet symbols, one above the line and one below the line, points to one of the joints of the structure. Value ".5" is placed to the left of the fillet symbol, both above and below, and is labeled "Size of weld." Value "2 hyphen 6" is placed to the right of the fillet symbol, both above and below, and is labeled "Pitch of welds." Figure D has the same structure as Figure C. An arrow with two fillet symbols placed above and below the lines points to one of the joints of the structure. Size of weld is measured ".25" at the top and ".312" at the bottom. Value "6" is placed to the right of fillet symbol above the line and value "4" is placed to the right of fillet symbol below the line. "6" and "4" are labeled "Lengths of welds." Figure E has the same structure as Figure D. A line is drawn at the right joint of the structure, connecting the edges of the two blocks. An arrow with a fillet symbol below the line points to the drawn line. Value ".25 cross .5" enclosed inside parentheses is placed to the left of the fillet symbol.

21.12 Dimensioning of Fillet Welds

the size dimensions are omitted from the symbols.

No length dimension is needed for a weld that extends the full distance between abrupt changes of direction. For each abrupt change in direction, an additional arrow is added to the symbol, except when the weld all around symbol is used.

Fillet Weld Length

Lengths of fillet welds may be indicated by symbols in conjunction with dimension lines (Figure 21.13a). The extent of fillet welding may be shown graphically with section lining if desired (Figure 21.13b).

Illustration has 2 figures labeled A and B. Figure A has a miniature diagram that represents an "H" placed horizontally over a surface, such that the arms of the character are the edges of the blocks to be welded, and the crossbar is the welding. The diagram adjacent to it represents how to mark lengths in a fillet weld diagram. Two horizontal bar are placed one above the other joined at the ends and cut somewhere near the center. The portion to the left of the cut is smaller to the portion to the right of the cut. The gap between the two bars is the weld spot. 4 extension lines are marked across the whole structure. 1 at the left edge, 1 at the right edge, and 2 in the middle. For the left portion, a dimension line at the top enclosed within first 2 extension lines reads "5-inch hyphen 0." An arrow (reference line with a leader line) with two arrowheads, one pointing to the bar at the top and other to the bottom has two fillet symbols, one above the line and one below the line. Value ".5" is indicated to the left of the symbols. Within the second and the third extension lines, a dimension line reads "24-inch hyphen 0." An arrow (reference line with a leader line) with two arrowheads, one pointing to the bar at the top and other to the bottom has two fillet symbols, one above the line and one below the line. Value ".5" is indicated to the left of the symbols. Value "2 hyphen 6" indicated to the right of the symbols. Within the last two extension lines, the dimensions and fillet readings are the same as the one between the first two extension lines. Figure B has a single horizontal bar, joined to a block whose top edges are cut. At the top of the horizontal bar, section lines are drawn at the left and at the right. Extension lines are drawn at the bottom, on the edges and two in the middle. Dimension lines read 6 at the ends and 4 in the middle. An arrow with a fillet symbol below and fillet length ".312" points to the section lines at the left edge of the bar. An arrow with a fillet symbol below and fillet length ".5" points to the section lines at the right edge of the bar.

21.13 Lengths of Fillet Welds

Intermittent Fillet Welding

Chain intermittent fillet welding is indicated as shown in Figure 21.14a. If the welds are staggered, the weld symbols are staggered (Figure 21.14b).

Illustration has two sets of figures explaining intermittent welds and their symbols.

Figure A has representations of desired welds and Symbol. The desired welds show the top view of a structure formed using two rectangular blocks placed perpendicular to each other. Both joints are welded at six spots, at the ends and the middle. The length of each welding spot is measured "2," while the pitch between two weld spots is measured "5." The symbol representing this welding diagram has a horizontal bar above which a vertical bar is placed perpendicular to it at the center, forming an inverted T. An arrow points to the left crook of T, with two fillet symbols one placed above reference line and another below, such that the vertical lines fall on the same line. Value ".25" is placed to the left of the symbols and Value "2 hyphen 5" is placed to the right of fillets. The welds at two ends are labeled "Locate welds at ends of joint." Figure B has representations of desired welds and Symbol. The desired welds show the top view of a structure formed using two rectangular blocks placed perpendicular to each other. Both joints are welded at four spots, two on either side of the joints, in a zig-zag fashion. The length of each welding spot is measured "3." The pitch between two weld spots on the same side is measured "10," while the pitch between two weld spots on different sides is measured "5." The symbol representing this welding diagram has a horizontal bar above which a vertical bar is placed perpendicular to it at the center, forming an inverted T. An arrow points to the left crook of T, with two fillet symbols one placed above reference line and another below, in a zig-zag manner. Value ".25" is placed to the left of the symbols and Value "3 hyphen 10" is placed to the right of fillets. The welds at two ends are labeled "Locate welds at ends of joint."

21.14 Intermittent Welds

Surface Contour and Fillet Welds

Unfinished flat-faced fillet welds are indicated by adding the flush symbol (see Figure 21.5), to the weld symbol (Figure 21.15a). If fillet welds are to be made flat-faced by mechanical means, add the flush-contour symbol and the user’s standard finish symbol to the weld symbol (Figures 21.15b through d). These finish symbols indicate the method of finishing (C = chipping, G = grinding, M = machining, R = rolling, H = hammering) and not the degree of finish. If fillet welds are to be finished to a convex contour, the convex-contour symbol is added, together with the finish symbol (Figure 21.15e).

Illustration represents Surface and Contour of Fillet welds with 5 figures labeled A to E.

Figure A has an arrow with a fillet symbol below the line. A line matching the length of the hypotenuse of the triangle is drawn parallel to it. Figure B has the same diagram shown in Figure A and character "G" is placed next to that parallel line. Figure C has an arrow with a fillet symbol above the line. A line matching the length of the hypotenuse of the triangle is drawn parallel to it. Character "M" is placed next to the line. Figure D has an arrow with two fillet symbols above and below the line. 2 lines matching the length of the hypotenuses of the triangles are drawn parallel to them. Character "C" is placed next to the parallel line, both above and below. Figure E has an arrow with a fillet symbol above the line. An arc is drawn above the hypotenuse of the triangle, and character "M" is placed over the arc.

21.15 Surface Contour of Fillet Welds

21.5 Groove Welds

In Figure 21.16, various groove welds are shown in the top row with their corresponding symbolic representations shown below. The sizes of the groove welds (depth of the V, bevel, U, or J) are indicated on the left of the weld symbol. For example, in Figure 21.16a, the size of the V-weld is .50″, in Figure 21.16b the sizes are .25″ and .875″, in Figure 21.16c the size is .75″, and in Figure 25.16d the size is .25″. For the symbol in Figure 21.16d the size is followed by .125″, which is the additional “root penetration” of the weld. In Figure 21.16e, the root penetration is .156″ from zero, or from the outside of the members. Note the overlap of the root penetration in this case.

Illustration represents Groove Welds using 5 figures labeled A to E.

Figure A shows two horizontal bars welded using "V" process. The groove angle is 60 degrees. The penetration of weld is .5, while the root opening is .125. The same measurements are also indicated in the symbol. Figure B shows two horizontal bars welded using "V" process but with a slight variation in the shape of the weld. The groove angle is 45 degrees. The root opening is .125. The penetration of the weld is .875 at one and .25 at the other end. The same measurements are also indicated in the symbol. Figure C shows two horizontal bars welded using "U" process. The root opening is "0." The groove angle is 30 degrees. The penetration of weld is .75. Figure D shows two horizontal bars welded using V process. The groove angle is 90 degrees. Root opening is 0. Penetration is .25 at the wider part and .125 at the lower, narrower part. Figure E shows two horizontal bars welded using square process twice. The root opening is 0. The penetration is .156 for both welds.

21.16 Groove Welds

The root opening or space between members, when not covered by a company standard, is shown within the weld symbol. In Figures 21.16a and b, the root openings are .125″. In Figures 21.16c through e, the openings are zero.

The groove angles, when not covered by a company standard, appear just outside the openings of the weld symbols (Figures 21.16a and b).

A general note may be used on the drawing to avoid repeating the symbols, such as

ALL V-GROOVE WELDS TO HAVE 60° GROOVE ANGLE UNLESS OTHERWISE SHOWN

However, when the dimensions of one or both of two opposite welds differ from the general note, both welds should be completely dimensioned.

When single-groove or symmetrical double-groove welds extend completely through, the size need not be added to the welding symbol. For example, in Figure 21.16a, if the V-groove extended entirely through the joint, the depth or size would simply be the thickness of the stock and would not need to be indicated in the welding symbol.

Surface Contour and Groove Welds

When groove welds are to be approximately flush without finishing, add the flush-contour symbol (see Figure 21.5) to the weld symbols (Figures 21.17a and b). If the welds are to be machined, add the flush-contour symbol and the user’s standard finish symbol to the weld symbol (Figures 21.17c and d). These finish symbols indicate the method of finishing (C= chipping, G = grinding, M = machining) and not the degree of finish. If a groove weld is to be finished with a convex-contour, add the convex-contour and finish symbols, as in Figure 21.17e.

Illustration represents Surface Contour of Groove welds with 5 figures labeled A to E.

Figure A has an arrow with a square weld symbol placed over it. A short horizontal line is drawn above the square weld symbol, without touching it. Figure B has an arrow with an "X" marked on the line such that the line passes through the intersection of X. Two horizontal lines are drawn one at the top of X and one at the bottom, without touching it. Figure C has an arrow with a Back weld at the top and a "V" weld at the bottom. Two horizontal lines are drawn one at the top of back weld symbol and one at the bottom of "V", without touching it. Character "G" is placed below the line. Figure D has an arrow (with a reference line and a zig-zag leader line,) has 2 "Bevel" symbols placed on it forming a "K" such that the reference line passes through the crook of K. A short horizontal line is placed above the K, without touching it. Character "G" is placed above the horizontal line. Figure E has an arrow with two square weld symbols, one above and one below. Two sets of an arc and a character "C", one placed below and one placed above.

21.17 Surface Contour of Groove Welds

21.6 Back or Backing Welds

A back or backing symbol opposite the groove weld symbol indicates bead-type welds used as back or backing welds on single-groove welds (Figure 21.18a). Dimensions for back or backing welds are not shown on the symbol, but may be shown, if necessary, directly on the drawing.

Illustration represents Back or Backing welding symbols with 5 figures labeled a to e.

Before the 5 figures, a graphical representation shows a V welding between two blocks. Figure A has two blocks placed horizontally and joined. An arrow points to the joint of the blocks, with a backing weld symbol at the top and a "V" symbol at the bottom. Figure B has an arrow with a V symbol at the top and a backing symbol at the bottom. A short horizontal line is drawn below the backing symbol. Figure C has an arrow with a zig-zag leader line. A "J" symbol is placed below and a backing symbol is placed above. A short horizontal line and character "M" are placed above the backing symbol. Figure D has an arrow with a Bevel symbol placed below and a backing symbol placed above. A short horizontal line and character "C" are placed above the backing symbol. Figure E has an arrow with a "V" symbol placed above and a two backing symbols placed one below the other, below the reference line.

21.18 Back or Backing Weld Symbols

A flush contour symbol included in the weld symbols indicates that the back or backing welds are to be approximately flush without machining (Figure 21.18b). If they are to be machined, the user’s finish symbol is added (Figures 21.18c and d). If the welds are to be finished with a convex contour, the convex-contour symbol and the finish symbol are included in the weld symbol, as shown in Figure 21.18e.

21.7 Surface Welds

The surface weld symbol indicates a surface to be built up with single- or multiple-pass bead type welds (Figure 21.19). Because this symbol does not indicate a welded joint, there is no arrow-side or other-side significance, so the symbol is always drawn below the reference line. Indicate the minimum height of the weld deposit at the left of the weld symbol, except where no specific height is required. When a specific area of a surface is to be built up, give the dimensions of the area on the drawing.

21.19 Surface Weld Symbol

21.8 Plug and Slot Welds

The same symbol is used for plug welds and slot welds. Figures 21.20a and d show the hole or slot that is made to receive the weld. If it is in the arrow-side member, place the weld symbol below the reference line, as shown Figures 21.20b and c. If it is in the other-side member, place the weld symbol above the line, as shown in Figures 21.20e and f.

Illustration of Plug Welds and Slot Welds.

Figure a shows the hole made to receive the desired weld. The drawing has two rectangular rods placed against each other, such that the top of the second is below that of the first. The second rod has an oval shaped opening mid-way through it. The horizontal centerline of this hole is drawn. The diameter of the oval is marked 75, and it is drawn to be rounded at a 30 degree angle at the top and bottom. Figure b, has a note reading Omit hole. From its top, an arrow shaped like the number 7 points to the centerline. On the horizontal top line segment of the arrow, a small rectangle is drawn, with its width marked as 0.75, and 30 degrees written below it. Figure c displays a larger rectangle, with its horizontal and vertical centerlines marked. A solid horizontal line runs a little below the top margin, and a dashed horizontal line runs a little above the bottom margin of the rectangle. The 7-shaped arrow, with the rectangle on it, now points to the center of the rectangle, with similar dimensions marked. Figure d is similar to a, and has the same caption, Desired weld. The difference is that the oval opening is placed on the first rod rather than on the second. Figure e is similar to b, except that the hidden lines of the hole are drawn on either side of the centerline, which passes through both rods. Figure f is similar to figure c. In addition, a horizontal dotted oval is drawn with the center of the rectangle as its center. The width of the oval is marked 0.75. The distance between the center of the rectangle to its bottom and right margins is 1.25 and 1.625 respectively.

21.20 Plug and Slot Welds

Place the size of a plug weld (which is the smallest diameter of the hole, if countersunk) at the left of the weld symbol. If the included angle for the countersink of a plug weld is in accordance with the user’s standard, omit it; otherwise, place it adjacent to the weld symbol as shown in Figures 21.20b and c.

A plug weld is understood to fill the depth of the hole unless its depth is indicated inside the weld symbol, as shown in Figure 21.21a. The pitch of plug welds is shown at the right of the weld symbol (Figure 21.21b). If the weld is to be approximately flush without finishing, add the flush-contour symbol, as in Figure 21.21c. If the weld is to be made flush by mechanical means, a finish symbol is added (Figure 21.21d). Flush-contour and finish symbols are used the same way for slot welds and for plug welds.

Illustration of the different Plug Welds.

Five figures are labeled alphabetically, all showing a horizontal line with an arrow head, and a small rectangular box attached to the line. Figure a shows the arrow head proceeding from the right end of the horizontal line and pointing upward. The arrow makes an acute angle with the line. The rectangular box is attached to the bottom side of the line and has the value 0.5 written within it. Figure b shows the arrow head proceeding from the left end of the horizontal line and pointing downward. The arrow makes an obtuse angle with the bottom side of the line. The rectangular box is attached to the top side and has the value 6 written beside it. Figure c is similar to figure b, except that the box is drawn on the under-side of the line and a small line is drawn along its length. Figure d shows the arrow head proceeding from the left end of the horizontal line and pointing upward. The arrow makes an acute angle with the top side of the line. The rectangular box is also attached to the top side and has a small line drawn along its length marked with an M. Figure e shows the arrow head proceeding from the right end of the horizontal line and pointing downward. The arrow makes an obtuse angle with the line. The rectangular box is attached to the bottom side of the line and has DET C written beside it.

21.21 Plug Welds

Indicate the depth of filling for slot welds the same way as for plug welds (Figure 21.21a). The size and location dimensions of slot welds cannot be shown on the welding symbol. Show them directly on the drawing (Figure 21.20f) or in a detail with a reference to it on the welding symbol, as shown in Figure 21.21e.

21.9 Spot Welds

The spot weld symbol, with the required welding process indicated in the tail, may or may not have arrow-side or other-side significance. Show dimensions on the same side of the reference line as the symbol, or on either side when the symbol is centered on the reference line and no arrow-side or other-side significance is intended.

The size of a spot weld is its diameter. Show this value at the left of the weld symbol on either side of the reference line (Figure 21.22a). If you need to indicate the minimum acceptable shear strength in pounds per spot, instead of the size of the weld, place this value at the left of the weld symbol, and indicate pitch at the right of the weld symbol, as shown in Figure 21.22b. In this case the spot welds are 3″ apart.

Illustration of the different Spot Welds.

Five figures are labeled alphabetically, all showing a horizontal line with an arrow head on one end. The non-arrow side of the line, shows the line splitting into two small line segments. A small circle is attached to the line. Figure a shows the arrow head proceeding from the right end of the horizontal line and pointing upward. The arrow makes an obtuse angle with the line. The circle is placed on the top side of the line and has the Size of the weld (diameter) value 0.25 inches written beside it. Figure b shows the arrow head proceeding from the left end of the horizontal line and pointing downward. The arrow makes a reflex angle with the line. The circle is placed on the top side of the line and has the Strength of the weld, 700, and the Pitch of the welds, 3 written one on either side of it. Figure c is similar to figure b, except that the line bisects the circle. The number of welds (4) is written over the circle. Figure d is similar to figure a, except that the line bisects the circle, and a small horizontal line is drawn below it. Figure e is also similar to figure a, except that the arrow makes an acute angle with the line. In addition, a rugged-margin rectangle is drawn above the line. The centerline of the rectangle is drawn, with a dotted line above it, and a solid line below it. The arrow points to the centerline. Three vertical extension lines are drawn: one from the left margin of the rectangle, the other from a little inside this margin, and a third a little within the right margin. The distance between the first and second lines is marked 1 and that between the second and third is marked 10.

21.22 Spot Welds

If a joint requires a certain number of spot welds, give the number in parentheses above or below the symbol, as in Figure 21.22c. If the exposed surface of one member is to be flush, add the flush-contour symbol above the symbol if it is the other-side member, and below it if it is the arrow-side member, as in Figure 21.22d. Figure 21.22e shows the welding symbol used in conjunction with ordinary dimensions.

21.10 Seam Welds

The seam weld symbol, with the welding process indicated in the tail, may or may not have arrow-side or other-side significance. Dimensions are shown on the same side of the reference line as the symbol, or on either side when the symbol is centered on the reference line and no arrow-side or other-side significance is intended.

The size of the seam weld is its width. Show this value at the left of the weld symbol, on either side of the reference line (Figure 21.23a). If you need to indicate the minimum acceptable shear strength in pounds per linear inch, instead of the size of the weld, place this value at the left of the weld symbol, and show the length of a seam weld at the right of the weld symbol, as in Figure 21.23b. In this case, the seam weld is 5″ long. If the weld extends the full distance between abrupt changes of direction, no length dimension in the symbol is given.

Illustration of the different Seam Welds.

Five figures are labeled alphabetically, all showing a horizontal line with an arrow head on one end. The non-arrow side of the line, shows the line splitting into two small line segments. A small circle, with two small horizontal lines cutting it, is attached to the line. Figure a shows the arrow head proceeding from the right end of the horizontal line and pointing upward. The arrow makes an obtuse angle with the line. The circle is placed on the bottom side of the line and has the Size of the weld (width) value 0.25 inches written beside it. Figure b shows the arrow head proceeding from the left end of the horizontal line and pointing downward. The arrow makes a reflex angle with the line. The circle is placed on the top side of the line and has the Strength of the weld, 2000, and the Length of the weld, 5 written one on either side of it. Figure c is similar to figure b, except that the line bisects the circle. The length of the weld and the pitch of welds is written as 2 4 beside the circle. Figure d is similar to figure a, except that the line bisects the circle, and a small horizontal line is drawn below it. Figure e is also similar to figure a, except that the arrow makes an acute angle with the line. In addition, a rugged-margin rectangle is drawn above the line. The centerline of the rectangle is drawn, with a dotted line above it, and a solid line below it. The arrow points to the centerline. Three vertical extension lines are drawn: one from the left margin of the rectangle, the other from a little inside this margin, and a third a little within the right margin. The distance between the first and second lines is marked 1 and that between the second and third is marked 10.

21.23 Seam Welds

The pitch of intermittent seam welding is the distance between centers of lengths of welding. Show the pitch at the right of the length value (Figure 21.23c). In this case, the welds are 2″ long and spaced 4″ center to center.

When the exposed surface of one member is to be flush, add the flush-contour symbol above the symbol if it is the other-side member and below it if it is the arrow-side member (Figure 21.23d). Figure 21.23e shows the welding symbol used in conjunction with ordinary dimensions.

21.11 Projection Welds

In projection welding, one member is embossed in preparation for the weld (Figure 21.24a). When welded, the joint appears in section, as in Figure 21.24b. In this case, the weld symbols are placed below the reference lines (Figure 21.24c) to indicate that the arrow-side member is the one that is embossed. The weld symbols would be placed above the lines if the other member were embossed.

Seven figures are labeled alphabetically. Figure a, is titled Preparation. The drawing has two rectangular rods placed against each other, such that the top of the second is below that of the first. The first has a small ridge on its top surface, and the second rod has a curved bump mid-way through it, such that the bump is the part that touches the side of the first rod. The horizontal centerline of the bump is drawn, and its diameter is marked. Figure b, is titled Weld. The drawing has two rectangular rods placed against each other, such that the top of the second is below that of the first. The first has a ridge along its left side. The middle portion of the joining of the two rods, is highlighted by a small filled oval. To the left the rod with the bump is displayed, with its diameter marked. Figure c is titled Symbol, and shows a rectangle to the right, with its centerline drawn. A solid horizontal line is drawn above the centerline, and a dotted horizontal line is drawn below it. A vertical line bisects the rectangle. The ends of this line are bent to the right at right angles, and both have arrowheads marked A. Another horizontal line with an arrow head on one end, is to the left of the rectangle. The non-arrow side of the line, shows the line splitting into two small line segments, labeled PW (See Det. B). A small circle, is attached to the lower side of the horizontal line, which then passes through the left margin of the rectangle. The arrowhead is drawn at an obtuse angle to the line, and points to the center of the rectangle. The next three figures shows the horizontal line and circle arrangement alone. Figure d shows the arrow head proceeding from the right end of the horizontal line and pointing downward. The arrow makes a reflex angle with the line. The circle is placed on the underside of the line and the Size (diameter) is marked 0.25 inches beside it. Figure e shows the arrow head proceeding from the left end of the horizontal line and pointing downward. The arrow makes a reflex angle with the line. The circle is placed on the top-side of the line and the Strength, Pitch, and the number of welds are marked 500, 6, and 4 beside it. The non-arrow end is labeled PW. Figure f shows the arrow head proceeding from the right end of the horizontal line and pointing upward. The arrow makes an obtuse angle with the line. The circle is placed on the top-side of the line and a small horizontal line is drawn above it. The non-arrow end is labeled PW. Figure g is similar to figure f, except that the arrow makes an acute angle with the line, and the circle is placed below the line. The values 0.25 and 2 are written on either side of the circle. The non-arrow end is labeled PW. In addition, a rugged-margin rectangle is drawn above the line. The centerline of the rectangle is drawn, with a dotted line above it, and a solid line below it. The arrow points to the centerline. Three vertical extension lines are drawn: one from the left margin of the rectangle, the other from a little inside this margin, and a third a little within the right margin. The distance between the first and second lines is marked 1 and that between the second and third is marked 10.

21.24 Projection Welds

Projection welds are dimensioned by either size or strength. The size is the diameter of the weld. This value is shown to the left of the weld symbol (Figure 21.24d). If you need to indicate the minimum acceptable shear strength in pounds per weld, place the value at the left of the weld symbol (Figure 21.24e). Indicate the pitch at the right of the weld symbol (Figure 21.24e). In this case, the welds are spaced 6″ (152 mm) apart. If the joint requires a definite number of welds, give the number in parentheses (Figure 21.24e). If the exposed surface of one member is to be flush, add the flush-contour symbol (Figure 21.24f). Figure 21.24g shows the welding symbol used in conjunction with ordinary dimensions. The welding process reference is required in the tail of the symbol.

21.12 Flash and Upset Welds

Flash and upset weld symbols have no arrow-side or other-side significance, but the supplementary symbols do. A flash-welded joint is shown in Figure 21.25a, and an upset-welded joint in Figure 21.25b. The joint after machining flush is shown in Figure 21.25c. The complete symbol (Figure 21.25d) includes the weld symbol together with the flush-contour and machining symbols.

The drawing shows flash and upset welds.

The drawing shows six stages of welding. The first stage represents flash welded where two rectangles are joint one over the other vertically and the joints are shown uneven. The second stage represents upset welded where the joints of the two rectangles are shown little merged. The third stage represents after machining where the joints are evenly fixed. The fourth drawing represents the symbol where the evenly joint rectangle is indicated and the symbol shows a rightward Y with two parallel vertical lines on the stem of Y and a horizontal line placed parallel above and below the vertical lines. M represents machine flush is shown above and below the horizontal lines and the end of Y reads FW represents process reference. The fifth stage represents after griding to smooth contour where the joints are shown bulged. The sixth stage represents the symbol of an even joint where the symbol shows a rightward Y with two parallel vertical lines on the stem of Y and an upward open parenthesis and a close parenthesis is placed parallelly above and below the vertical lines. G represents Finish to smooth contour is shown above and below the horizontal lines and the end of Y reads UW represents process reference.

21.25 Flash and Upset Welds

If the joint is ground to smooth contours (Figure 21.25e), the resulting welding drawing and symbol would be constructed as in Figure 21.25f, which includes convex-contour and grind symbols. In either Figure 21.25d or f, the joint may be finished on only one side, if desired, by indicating the contour and machining symbols on the appropriate side of the reference line. The dimensions of flash and upset welds are not shown on the welding symbol. Note that the process reference for flash welding (FW) or upset welding (UW) must be placed in the tail of the symbol.

21.13 Welding Applications

A typical example of welding fabrication for machine parts is shown in Figure 21.26. In many cases, especially when only one or a few identical parts are required, it is cheaper to produce by welding than to make patterns and sand castings and do the necessary machining. Thus, welding is particularly adaptable to custom-built constructions.

Figure illustrating the Application of Welding-Fabrication for Machine Parts.

The Welding Fabrication is depicted as follows. A thin rectangular rod is placed vertically at the center. On the top and bottom ends of the rod are two solid lines, each enclosed by a pair of dotted lines. A rectangle is attached to the mid-way along the rod, to its left, labeled No Pant of Weld Spatter. The left and right sides of this rectangle are drawn with double lines. Two dotted horizontal lines run along the top and bottom margins of the rectangle, and extend into the rod. The portion of the rod, which holds the corners of the rectangle has a pair of triangles drawn on either side of the inner surface of the rod. Each pair of triangle has a space equal to the width of the rectangle. A pair of dotted lines are on either side of these triangles to the top and bottom. A horizontal line to the left of the rod, and above the rectangle is bent downward, at a reflex angle, and has an arrow head pointing to the top-left triangle within the rod. Similarly, another horizontal line is drawn to the right of the rod, pointing to the top-right triangle of the rod. A circle is drawn with the point that the line bends as its center, on both arrowheads. On the bottom side of the horizontal line of the arrow heads, a triangle is drawn, with its base disjoint from the other two sides. The one to the left resembles a right triangle and the one to the left resembles an equilateral triangle.

21.26 Application of Welding-Fabrication for Machine Parts (Courtesy of Dynojet Research, Inc.)

Welding is also suitable for large structures that are difficult or impossible to fabricate entirely in the shop, and it is coming into greater use for steel structures, such as building frames, bridges, and ships. A welded beam is shown in Figure 18.16, and a welded assembly of diagonal bracing between two columns is shown in Figure 18.17. A welded truss is shown in Figure 21.27. It is easier to place members in such a welded truss so that their center-of-gravity axes coincide with the working lines of the truss than is the case in a riveted truss. Compare this welded truss with the riveted truss in Figure 18.14.

21.27 A Welded Truss

21.14 Welding Templates

Welding templates can simplify drawing welding symbols by hand (which may be done in pencil or ink). They have all the forms needed for drawing the arrow, weld symbols, and supplementary symbols, as well as an illustration of the complete composite welding symbol for quick reference.

21.15 Computer Graphics

Welding symbols libraries available in CAD (Figure 21.29) allow for rapid application of accurate, uniform symbols that are in compliance with AWS standards (Figure 21.28). In addition to standard symbols, many CAD programs permit the operator to create custom symbols as required.

Illustration of a CAD-Generated Welded Structure.

The basic structure is an elongated rectangle places horizontally. The top and bottom borders are double lined, and shaded. The top and bottom borders are labeled PL 1. The left and right borders are removed and replaced by what resembles a capital I. The stem of these Is are labeled W 14, and their upper horizontal line is also labeled W14. The whole rectangle is partitioned by a third uppercase I, the stem of which is labeled HP 14. The part where the lower horizontal line of this I, touches the inside of the bottom border, the border is erased. Extension lines are drawn from here. A vertical centerline is drawn through the stem of this I, and extended on either end. The top end is labeled with an encircled 1. The distance between the left extension line and the centerline, and that between the right extension line and the centerline is marked 1.5 inches. The following three horizontal lines are bent at an angle and have an arrowhead on one end, and the non-arrow end diverges and is labeled TYP. The first line is at the top-left, and bends at a reflex angle to point to the top line of the I forming the left border. A small triangle is drawn on the line, such that the line bisects the triangle, and its tip points to the right. The values 0.32 and 0.5 are written on either side of the line. The second line is drawn at the bottom-left, and its bends at an obtuse angle to point at the lower line of the same I. A small vertical line is drawn from the bottom of this line, and the value 0.625 is written beside it. The third line is drawn from the bottom-right, and it bends at an obtuse angle to point at the bottom of the I that divides the rectangle. A small right-triangle is placed with its base along the under-side of the line, and the value 0.625 is written on it. Two more arrows resembling an inverted L, are suspended on either side of the drawing. They point downward and are labeled E. A note at the bottom reads: Section B - B 0.75 inches equals 1 feel 0 feet.

21.28 CAD-Generated Welded Structural Detail

The drawing shows a computer vision production drafting symbols in three different tables.

The table represents basic welding symbols and their location significance. The first table shows four rows and seven columns. The row header reads arrow side, other side, both sides, and no arrow side or other side significance. The column header reads location significance, corner under the header flange, square, V, bevel, U, and J. The second table shows the similar number of rows and columns and the row header as table one. The column header reads location significance, flare V and flare bevel under the header groove, fillet, pluo or slot, spot or projection, and seam. The third table shows four rows and six columns. The row header reads the same as the other. The column header reads location significance, back or backing, surfacing, scarf for brazer joint, edge under flange, and supplementary symbols. The table shows various symbols under the respective rows and columns and few cells read not used.

21.29 Computervision Production Drafting Symbols

CAD at Work: Weld Symbols from CAD

Most CAD systems provide a way to quickly generate weld symbols to place in your drawing. The SolidWorks dialog box shown in Figure A allows you to select the symbol for type and size of weld, field placement, whether to add the all-around symbol, and special indications for contour and finish method. Once you have made your selections, the weld symbol as shown in Figure B is automatically generated from them, and you have only to click to place the symbol in your drawing.

Screenshot depicts the SolidWorks weld symbol properties dialog box.

In the properties dialog box, the ANSI Weld Symbol tab is selected and displays, Groove angle, and root opening text box with Inside and Arrow checkbox are shown beside them. Below them, two empty boxes are shown. Stagger weld checkbox is shown with the None is selected within the Finishing method drop-down list and None is selected from the Contour drop-down list. The Field/Site checkbox is selected with three boxes shown beside them. The first two boxes entered as .50 and Weld Symbol (highlighted) and another box is left empty. The around checkbox is selected. The field/site checkbox is left empty with three boxes shown beside them. The first two boxes entered as .50 and Weld Symbol (highlighted) and another box is left empty. An empty drop-down list box is shown on the right of three checkboxes. The concave is selected from the contour drop list and G-Grindir is selected within the finishing method drop list. The .1 is entered in the root opening textbox with an Arrow checkbox shown beside. The 45 is entered in the groove angle textbox with an Inside checkbox shown beside. The None is selected under the Joint with the drop-down list. Use document font checkbox is selected within the font section. The Closest is selected under the leader anchor drop-down list and None is selected from the Layer drop-down list. The Ok button shown is selected.

(A) SolidWorks Weld Symbol Dialog Box (Courtesy of SolidWorks Corporation.)

Figure depicts the automatically generated weld symbol.

(B) Automatically Generated Weld Symbol (Courtesy of SolidWorks Corporation.)

Specialized software such as Design Data’s SDS/2 allows you to design and model connections between members based on parameters that you define for each job. You can designate the material, edge distance, cope criteria, and other connection specifications, and SDS/2 will automatically generate connections. You can model all the details, for example, the fillet welds shown in Figure C, using the software’s 3D modeler. 2D drawings can be taken directly from the model, providing an accurate fit in the field.

Figure depicts the fillet welding in a 3D Model.

Portfolio

In the portfolio design on the left, a horizontal tube marked 1 is shown with two holes marked 3 on either side with a bolt marked 4 at the center. A clamp arm is shown on the left of the tube marked 2. On the right shows, a horizontal tube with two small vertical beams of 3 over 16 and 1 over 2 labeled "1 Bead along the top and 1 Bead along the bottom." The front view of the clamp arm shows a horizontal box with a hexagon shape is placed between the two circles on either side. The base of the hexagon at the top and bottom labeled "3 over 16." A vertical line is shown on the horizontal box labeled "1 over 8." The length of the vertical line to the horizontal bar is marked as 9.13. The two circles of 3 over 16 and 1 over 2 is labeled "1 Bead along the top and one bead along the bottom." The dimension of the circle is marked as .753 and 2 PLCS. At the top of the portfolio reads, Notes, Unless otherwise specified: 1. All dimensions are in decimal inches. 2. Remove all burrs and sharp edges. 3. Remove all tooling marks. 4. Dimensions and tolerances shall be held after plating or finish. At the middle reads: This part is produced from an electronic data file provided to the vendor, dimensions shown are for reference, any other dimensions should be obtained from the model. On the top right shows a revision table with three rows of ECR number, Revision, Description, Date, and Approved. At the bottom left shows a table consists of details of the item number, quantity, part number, and description. On the bottom right shows a tolerances section and title section. In the tolerances section shows the details of material, finish, tolerances in decimal and fraction, created, last update, designed, and approved. In the title section shows the details of Clamp arm-left with size, part number, revision, scale, release date, sheet and of number.

Welding symbols specify the welds for attaching the tube, bushings, nut, and plate for the clamp arm. (Courtesy of Dynojet Research, Inc.)

Drawing shows the use of welding symbols to indicate the attachment of plates to a beam.

Welding symbols specify how plates attach to a structural beam in this drawing created from a 3D model using SDS/2 software. (Courtesy of Paul Hergett, Midwest Steel Industries.)

Key Words

Chapter Summary

• The four basic types of arc and gas welds are back, fillet, plug, and groove.

• The four basic types of resistance welds are spot, projection, seam, and flash.

• The welding symbol defines the location of the weld, the type of weld, and the welding process.

• Groove welds are classified as square, V, bevel, U, and J.

• A weld symbol below the leader line indicates that the weld is on the same side of the joint as the leader arrow.

Review Questions

1. Which indicates the weld is on the opposite side: the weld type shown above the line, or below the line?

2. Draw the shapes for the following weld symbols: fillet, square, bevel, V, U, J.

3. List five names describing the ways the material can be oriented in forming a joint.

4. List the five types of groove welds.

5. Draw a typical welding symbol and label its parts.

6. Which type of weld would join two pieces at 90°?

7. What is a field weld?

Chapter Exercises

The following problems are given to familiarize you with some applications of welding symbols to machine construction and to steel structures.

For Exercises 21.1–21.21 Change to a welded part. Make working drawings, using appropriate welding symbols.

Figure shows the isometric view of a solid model resembling an index feed with its dimensions labeled.

A 3-dimensional figure representing an index feed has a rectangular block with a block in the shape of a trapezium, placed over it, such that, two edges of the trapezium and two edges of the block are fall on the same lines. The trapezium occupies almost half of the rectangular block's area. The upper surface of the trapezium has 2 planes inclined at different angles. At one of the corners of the block, a small layer of the corner is cut-away creating a triangular portion on the surface of the block. A drill hole is at the center of the block. The block is shown to have a small beam at the bottom center. The dimensions are as follows. The length of the rectangular block is 3.25, while the width is 2.50. The thickness of the portion cutaway at the corner of the rectangle is .19. The width of the beam below .750, while the thickness is .19. The length of the part of the rectangle to the right of the beam is 1.00, while to the part at the left is 1.25. The height of the trapezium block is .62, while, the height of the entire structure is 1.56. The diameter of the drill hole is .50. The two planes that form the upper surface of the trapezium block are inclined at an angle of 40 degrees and 30 degrees. The length of one of the planes is .94. The text beside the figure reads "Heat Treat 10-250, CRS 1 Required."

Exercise 21.1

Figure shows an isometric projection of a Cam.

A 3-dimensional figure representing a Cam resembles a horseshoe with straight branches instead of curved ones and a slight projection at the toe part. The projection is like the rear end of a tube TV. The projection at the toe part and the sides resembling the branches of the horseshoe have drill holes. The parts of the Cam resembling the heel portion of the horseshoe have slight inward notches. The depth of the Cam including the projection at the rear end is 3.19, while the width is 2.24. The gap between the two branches is 1.19 at the toe end, while at the heel end it is .81. The width of a single branch is .53. The distance between one end of the branch and another is 2.12. The distance between the edges of the branch to the drill hole on the branch is .75. The diameter of the drill holes on the branches is approximately .620 to .630. The diameter of the drill hole on the toe part projection is approximately .50 to .56. The angle between the end of the wall and the side of the projection is 45 degree. The length of the branch at the heel part is .94. Text beside the figure reads CRS 1 Required FAO.

Exercise 21.2

Figure shows the isometric view of a solid model with its dimensions labeled.

The solid model has a rectangular frame with notches on two corners along its length. Two frames that resemble jibs of a yacht are placed over the rectangular frame in the middle with a gap between them. 4 drill holes, two on either side of the jibs are placed. The diameter of the 2 holes to the right of the jibs is 9. The 2 holes placed on the left are pointed out labeled "Ream for 8mm dowels - 2 holes." The length of the rectangular frame excluding the notch edges is 80. The length of the rectangular fame including the notch edges is 106. The distance between the left edge of the frame and the left jib is 27. The distance between the left edge of the frame and the right jib is 54. The width of the rectangular frame including the notch edge is 52. The distance between the two drill holes is 19, while the drill holes are placed at a distance of 13 from the edge of the frame. The thickness of the frame is 14. The jibs also have notches at the taller end. The height of the jibs excluding the notch is 5 while including the notch is 21. The jib on the left is slighted inclined at an angle of 30 degrees. A circle is drawn between the two jibs, to illustrate the space between them, and the diameter of the circle is 32. All dimensions are in metric. The text beside the diagram reads CRS 1 Required.

Exercise 21.3

Figure shows the drawing for machinists vise.

Exercise 21.4

Exercise 21.5

Exercise 21.6

Figure shows the side view drawing of Crossfade stop.

Exercise 21.7

Figure shows the drawing of Hinge Block.

Exercise 21.8

Exercise 21.9

Figure shows the engineering drawing of Control Block.

Exercise 21.10

Figure shows the drawing of Socket Bearing.

Exercise 21.11

Figure shows the front view drawing of Anchor Bracket.

Exercise 21.12

Figure shows the side view of Anchor bracket.

Exercise 21.13

Figure shows a drawing of a welding part.

Exercise 21.14

Exercise 21.15

Exercise 21.16

Exercise 21.17

Figure shows the auxiliary drawing of bearing.

Exercise 21.18

Figure shows a side view of the mounting bracket.

Exercise 21.19

Figure shows Ejector Base drawing in half size.

Exercise 21.20

Figure shows Trip Lever with Front, top, and partial side views.

Exercise 21.21

Figure depicts the roof truss drawing with the help of working lines and working points are shown.

Roof Truss Exercises

For Exercises 21.22–21.24 refer to the Roof Truss drawing shown.

Exercise 21.22 Make a half-size drawing of the joint at the center of the lower chord of the truss where the chord is supported by two vertical angles. The chord is a structural tee, cut from an, 8″ × 5–1/4″, 17 lb, wide flange shape. Draw the front and side views, and show the working lines, the two angles, the structural tee, and all welding symbols.

Exercise 21.23 Make a half-size front view, showing the welding symbols, of any joint of the roof truss in which three or four members meet.

Exercise 21.24 Draw half-size front, top, and left-side views of the end joint of the truss in showing the welding symbols.

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