Chapter

Welding Joints, Positions, and Symbols

3

Objectives

• Identify the five basic welding joints.

• Identify and describe the various welds that may be used in each welding joint.

• Label the parts or areas of a grooved butt weld and a fillet weld.

• Locate and apply required weld and joint information from an AWS welding symbol.

• List and describe the four welding positions.

© Goodheart-Willcox Co., Inc.

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Basic Weld Joints

• A welder should understand the type and location of welds needed by reading the welding symbols • A weld joint refers to how the parts are assembled prior to the welding • The item to be joined is base metal or base material © Goodheart-Willcox Co., Inc.

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Basic Weld Joints

• There are five types of joints used in welding – Butt – Lap – Corner – T-Joint – Edge (American Welding Society) © Goodheart-Willcox Co., Inc.

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Butt Joint

• Butt joints are used when parts are joined edge-to edge • Edge preparation refers to how the edges are shaped prior to welding • A groove weld is made by fusing molten filler metal into a butt joint © Goodheart-Willcox Co., Inc.

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Butt Joint

• The various parts of a groove joint have names – Groove face – Groove angle – Bevel angle – Weld root – Root face © Goodheart-Willcox Co., Inc.

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Butt Joint

• Various terms are used to describe a completed groove weld – Weld face – Face reinforcement – Weld toe – Root reinforcement – Joint penetration – Weld size © Goodheart-Willcox Co., Inc.

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Lap and Corner Joints

• A lap joint is formed by two overlapping pieces of base metal • A corner joint is formed by placing two pieces of base metal perpendicular or at an angle to one another – Inside corner joints are welded along the inside of the joint – Outside corner joints are welded along the outside edge of the joint © Goodheart-Willcox Co., Inc.

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T- Joint

• A T-joint is formed by two pieces of base metal that are at an angle of approximately 90 • The edges may be prepared as a square, bevel grooved, J-grooved, or flare-bevel-groove joint © Goodheart-Willcox Co., Inc.

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Edge Joint and Flange Joint

• An edge joint is formed when the surfaces of two pieces are in contact and their edges are even • A flange joint is formed when the edge of one or more pieces is bent to form a flange © Goodheart-Willcox Co., Inc.

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Flare-Groove Joint

• Flare-groove joints are formed when the flanged edges of one or both pieces are placed together to form a single-flare-bevel or a double-flare-groove © Goodheart-Willcox Co., Inc.

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Types of Welds

• A weld is a fused joint between two or more pieces of metal or nonmetal • Fillet welds are made at the intersection of a surface and an edge or in a corner where two surfaces meet • A groove weld is made in a groove or gap between two pieces of metal © Goodheart-Willcox Co., Inc.

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Types of Welds

• A fillet weld is made up of three primary dimensions – Weld size – Effective throat – Leg © Goodheart-Willcox Co., Inc.

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Bead Welds and Weld Passes

• A weld bead is one weld pass of filler metal that is added to a weld joint • The first weld pass is the root pass • The second weld pass is the filler pass • The final weld pass is the cover pass • Generally, a weld bead should not be thicker than 1/4″ © Goodheart-Willcox Co., Inc.

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Bead Welds and Weld Passes

• Three weld passes are used in this example • The cover pass is a weave bead © Goodheart-Willcox Co., Inc.

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Stringer Bead and Weave Bead

• A weld bead may be a stringer bead or a weave bead • A stringer bead is used when a standard bead width is acceptable • A weave bead is used to create a wider weld pool • The crescent motion is a popular pattern for a weave bead © Goodheart-Willcox Co., Inc.

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Joint Geometry

• Joint geometry is defined as the shape and dimensions of a joint, in cross section, prior to welding • Joint geometry is generally determined by a welding engineer or designer • The joint geometry design should provide space for the welder to reach near the bottom of the weld joint © Goodheart-Willcox Co., Inc.

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Preparation

• The edges of thick metal are prepared for welding – Flame cutting – Gouging – Machining • Preparation allows the weld to penetrate as deep as required © Goodheart-Willcox Co., Inc.

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Joint Alignment

• The alignment of a joint before welding is very important • A tack weld is a small weld used to hold pieces in alignment • Parts may also be held mechanically using clamps or other devices (Bessey Tools North America) © Goodheart-Willcox Co., Inc.

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Penetration

• A completed weld joint must be as strong as the base metal • The weld must penetrate deeply into the base metal to be strong • Penetration is the depth of fusion of the weld below the surface © Goodheart-Willcox Co., Inc.

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Welding Positions

• Welds may be made in various welding positions – Flat welding position – Horizontal welding position – Vertical welding position – Overhead welding position • Welding positions are determined by the positions of the weld axis and weld face © Goodheart-Willcox Co., Inc.

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Welding Positions

• The weld axis is an imaginary line running lengthwise through the center of a weld © Goodheart-Willcox Co., Inc.

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The Welding Symbol

• Welding symbols are used on drawings of parts and assemblies that are joined together by welding • A complete welding symbol contains all the information about a welded joint • Dimensions may be in SI Metric units or in US Customary units © Goodheart-Willcox Co., Inc.

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Reference Line, Arrowhead, and Tail

• The reference line is always drawn as a horizontal line • The arrow may be drawn from either side of the reference line • The tail is used only when necessary to give additional information © Goodheart-Willcox Co., Inc.

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Weld Symbols

• Weld symbols may be part of the complete welding symbol and indicate the type of weld (American Welding Society) © Goodheart-Willcox Co., Inc.

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Arrow Side and Other Side

• On the drawing of a weld part, the arrow touches the line to be welded • The side of the metal that the arrow touches is called the arrow side • The opposite surface is called the other side • The arrow side information is always shown below the reference line © Goodheart-Willcox Co., Inc.

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Root Opening and Grove Angle

• The root opening is the space between the pieces at the bottom, or root, of the joint • Prior to welding, the two pieces will be spaced apart the distance indicated by the root opening • The root opening size appears inside the weld symbol © Goodheart-Willcox Co., Inc.

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Contour and Finish Symbols

• The shape of contour of the completed weld bead is shown in the welding symbol – Straight or curved line – Placed between the weld symbol and the finish symbol • If the weld is not to remain in an “as welded” condition, a finish symbol is used © Goodheart-Willcox Co., Inc.

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Depth of Bevel and Groove Weld Size

• The “S” position on the welding symbol – Indicates the depth of the bevel – May indicate the size or strength of welds – May show the size of each leg in a fillet weld • Groove weld size – Is the depth to which the weld penetrates into the base metal – Is given in parentheses in the “E” position on the welding symbol © Goodheart-Willcox Co., Inc.

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Depth of Bevel and Groove Weld Size

• This illustration shows the depth of the edge shape and groove weld size © Goodheart-Willcox Co., Inc.

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Length and Pitch of Weld

• Intermittent welding – Short sections of the weld are spaced across the joint – Used when full strength is not needed – The length dimension indicates the length of each weld – The pitch dimension indicates the distance from the center of one weld to the center of the next weld © Goodheart-Willcox Co., Inc.

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Length and Pitch of Weld

• Intermittent fillet welds may be required on both sides of a joint – With chain intermittent welds, welds begin and end at the same spots – With staggered intermittent welds, the welds are offset – This is shown on the welding symbol by offsetting the fillet weld symbols © Goodheart-Willcox Co., Inc.

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Length and Pitch of Weld

• This illustration shows a staggered weld • Notice the staggered fillet symbols © Goodheart-Willcox Co., Inc.

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Backing Welds and Melt-Through Symbols

• Weld joints that require complete penetration may be welded from both sides • A stringer bead or a cover pass may be all that is required • In such cases, a backing weld symbol is used • The melt-through symbol is used when 100% penetration is required on one-side welds © Goodheart-Willcox Co., Inc.

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Weld-All-Around and Field Weld Symbols

• The weld-all-around symbol indicates that the same type weld joint is to be used on all edges of a box or cylindrical part • When welds are to be made away from the shop, a field weld symbol is used © Goodheart-Willcox Co., Inc.

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Multiple Reference Lines

• Two or more reference lines may be used when a sequence of operations is to be done – The reference line nearest the arrow indicates the first operation – The reference line furthest from the arrow indicates the last operation © Goodheart-Willcox Co., Inc.

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Plug and Slot Welds

• A plug weld is a weld made in a hole that is round • A slot weld is a weld made in a hole that is not round • The pitch is the center-to-center distance in a series of plug or slot welds © Goodheart-Willcox Co., Inc.

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Spot Welds

• A spot weld is a method of joining two or more pieces together with a weld not at the edge of a part • The spot weld symbol is a small circle • Projection welding is another process used to produce spot welds © Goodheart-Willcox Co., Inc.

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Spot Welds

• The following information is given for a spot weld – Size – Strength – Spacing – Number of welds – Welding process © Goodheart-Willcox Co., Inc.

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Seam Welds

• A seam weld is another method of joining two or more pieces together – Lap joint – Butt joint • No hole or slot is cut into any parts • The size and strength of the weld are shown to the left of the weld symbol © Goodheart-Willcox Co., Inc.

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Review of Welding Symbols

• This illustration shows examples of various types of welds in various positions © Goodheart-Willcox Co., Inc.

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Electrode Angles

• Two terms are used to describe the electrode angle, or position, in relation to the material being welded – Travel angle – Work angle © Goodheart-Willcox Co., Inc.

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Travel Angle

• The travel angle is measured from a line perpendicular to the weld axis in the plane defined by the weld axis and electrode axis © Goodheart-Willcox Co., Inc.

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Travel Angle

• Backhand welding – The top of the electrodes leads the welding end of the electrode – The welding arc is pointing back toward the weld bead – The travel angle is called a drag angle or drag travel angle • Forehand welding – The welding end of the electrode points forward in the direction of travel – The travel angle is called a push angle or push travel angle © Goodheart-Willcox Co., Inc.

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Work Angle

• The work angle is measured from a line perpendicular to the major or nonbutting surface to the plane containing the weld axis and the centerline of the electrode © Goodheart-Willcox Co., Inc.

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Commonly Used Angles

• For a butt weld, the work angle is usually zero • For a fillet weld, the work angle is often 45 • Drag or push angles usually range from zero to 40 • A large push angle, up to 85 , is used for gouging © Goodheart-Willcox Co., Inc.

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