Edge and Corner Joints

Types of Joints

• Five basic joints used in welding include butt, T-, edge, lap, and corner joints.
• Corner, lap, and T-joints need fillet welds.
• Light-gauge sheet metal usually utilizes edge joints, which typically do not need extra filler metal.

T-Joints

• T-joints join two metal pieces at right angles (90°).
• Square T-Joints require no edge preparation.
• T-Joints are widely used because they are easy to fit, and are low cost
• Single bevel, double bevel, single J, or double J edge preparations can be used on thicker material, depending on loading conditions, distortion allowance, and filler weld material.

Lap Joints

• Lap joints are often used for welds joining two materials of different thicknesses.
• Little or no edge preparation is needed for lap joints.
• CSA W59 states, "The minimum overlap of parts should be five times the thickness of the thinner part joined, not less than 25 mm (1 in), while the gap between the mating surfaces should not exceed 2 mm (1/16 in)."
• If the weld does not require great strength, a single lap joint may be enough to provide a "tight" joint.
• Both sides of the joint should be welded when fluctuating, bending, or twisting loads are applied.

Corner Joints

• A corner joint joins two pieces at right angles, creating an L shape formed at the ends of both pieces.
• Two types of corner joints are open corner and closed corner.
• Open corner joints are used more often because of their excellent penetration
• Closed corner joints are normally recommended for light-gauge sheet metal.
• Preparing the edge of one or both pieces for thicker material, and allowing for a small root opening helps ensure maximum joint penetration.
• Steps to welding corner joints in heavy stress-loading applications:
  • Weld the joint from the inside.
  • Gouge to sound metal from the outside.
  • Weld from the outside.

Edge and Flanged Joints

• An edge joint connects two pieces of metal turned up at the edges.
• Edge joints are mostly used on light-gauge material, including sheet metal.
• A brake turns up the edges of sheet metal.
• Turned-up edges reduce the danger of burn-through on thin metal and prevent distortion; no additional filler metal is required.
• Edges must be prepared with plate to ensure sufficient penetration.
• A flange weld has at least one member with a flanged edge shape at the joint and is sometimes referred to a flanged weld.
• A flanged joint is considered a projecting ridge, rim, collar, or ring. It provides additional strength, stiffness, or surface area.
• Flanges can occur on any previously mentioned joints.
• Flanged joints increase strength and incur higher costs for formed materials.
• Uses for flanged joints include buildings and bridges, crane rails, construction cranes, other lattice structural designs, ridge materials for sealing surfaces, and access points in low-pressure tank applications.

Butt Joints

• A butt joint is formed when two pieces of metal are beside each other in the same plane.
• This joint is widely used because it is strong and joined relatively easily.
• Edge preparations are dependent on the thickness of the material.
• Square groove butt joints require no edge preparation.
• Single V-groove welds are normally used on material that is up to 19 mm (3/4 in) thick.
• Preparing for a single V-groove weld can be done by using an oxy-fuel cutting torch or a grinder.
• Complete penetration is required which can be identified by a keyhole leading edge of the weld and melted base material.
• Square groove butt joints work only with the oxy-acetylene welding process for material 3.2 mm (1/8 in) or less.
• When fitting the joint together, a small gap about the thickness of the plate should be used. A filler rod is an effective method.
• If multiple passes are used, the first root pass is the most important, with complete fusion, penetration, and reinforcement.
• Additional passes are called fill passes, and the final pass is known as the cap pass. The cap pass should provide a slightly convex bead.

Variations in Joint Design

• Edge preparation of weld joints can be done in several ways.
• Factors influencing the decision for edge preparation:
  • Material
  • Welding process
  • Thickness
  • Extent of penetration required
  • Load application
  • Welding distortion allowance
  • Cost
• Different joint types:
  • Butt joint
    • Square groove
    • V-groove
    • Bevel groove
    • U-groove
    • J-groove
    • Flare V-groove
    • Flare bevel groove
    • Edge flange
    • Braze
  • T-Joint
    • Fillet
    • Plug
    • Slot
    • Square groove
    • Bevel groove
    • J-groove
    • Flare bevel groove
    • Spot
    • Projection
    • Seam
    • Braze
  • Corner joint
    • Fillet
    • Flare bevel groove
    • Edge flange
    • Corner flange
    • Spot
    • Projection
    • Seam
    • Braze
  • Edge joint
    • Square groove
    • Bevel groove
    • V-groove
    • U-groove
    • J-groove
    • Edge flange
    • Corner flange
    • Seam
    • Edge • Lap joint
    • Fillet
    • Plug
    • Slot
    • Bevel groove
    • J-groove
    • Flare bevel groove
    • Spot
    • Projection
    • Seam
    • Braze

Weld Types

A weld merges materials by applying heat or pressure, and it often uses a filler material.

• Types of welds:
  • Surfacing welds
  • Fillet welds
  • Groove welds
  • Tack welds
  • Plug and slot welds

Surfacing Welds

• A surfacing (bead) weld that obtains desired properties or dimensions
• Deposited to build up the surface of metal replace metal on worn surfaces
• Buttering is buildup intended to be added to provide a buffer or a transition for another surface weld.
• Hardfacing creates a hard or tough surface to control wear.
• Cladding creates a corrosion- or heat-resistant layer.

Tack Welds

• Tack welds hold parts of a weldment in alignment.
• A tack weld is a short weld about 13 mm (1.2 in) long and can be temporary or permanent.
• Guidelines for tack welds:
  • Small welds-large tack welds need to be ground out before welding.
  • It's important to plan tacking sequences to keep the job straight
  • Welders should avoid lifting or turning with lightly tacked jobs
  • Electrodes used should be compatible with base and final welding material
  • Avoid leaving a crater on the end of the tack.

Edge Welds

• An edge weld is an edge, flanged butt, or flanged corner joint in which the full thickness of the members are fused.
• Edge welds are neither groove nor fillet welds

Plug and Slot Welds

• Made in the upper plate for plug and slot welds with holes or slots, respectively.
• Plug weld - A circular hole is made in one member of a joint that fuses it to another.
• Slot weld - An elongated hole is made in one member of a joint that fuses it to another.
• Plug and slot welds can be completely or partially filled, with the inside fillet being welded around the plug or slot.
• Filling the joints are often unnecessary.
• Arc spot and arc seam welds are made without holes or slots, where the upper sheet is melted and fused to the lower sheet.

Fillet Welds

• A fillet weld has a roughly triangular cross section, and joins 2 surfaces approximately at right angles.
• The strength of a fillet weld is governed by the effective throat thickness (the shortest distance from the root of the weld to its face, less any convexity).
• The size of a fillet weld is the leg length of the largest triangle inscribed within the weld cross section and is measured in millimetres (mm) or inches (in)
• Profiles need be precise with small dimensions adjusted to the nearest size in 1.6mm intervals.
• These type of welds require no special prep
• Used in lap, t or corner joints.
• Advantage of Intermittent fillet welds, the heat input to the joint may be less than for continuous fillet weld.
• Codes and standards govern requirements of fillet welds.
• Irregularities relate to the finished welds' shape.

Groove Welds

• Groove welds can be composed of a root, fill, and cap.
• The number of passes needed depends on the base metal thickness.
• Dimensions:
  • Root opening
  • Root face
  • Included angle
  • Base metal thickness
  • Throat
• Three basic forms of edge preparation
  • Square
  • Beveled
  • J profile
• Welding two members of a butt joint with diff. heights is sloped >1 in 2.5 slope.
• Taper prevents/ min. stress concentration
• single. Double, V-groove and Flare.
• Single employs Back ,melt through to insure joint when req.
• Backing mateial used when penetration is limited.

Welding Positions

• Four basic welding positions for all welding processes specifications, qualification tests, and instruction manuals:
  • Flat
  • Horizontal
  • Vertical
  • Overhead
• Equal sized plate corner joints can be completed on a work bench. Angled position needed for lap joints;
• True flat is horizontal upper side and face, and is is the best position because of gravity.
• In horizontal, weld axis is horzontal. Most difficult because gravity and the weld puddle flows lower.
• In vertical, plate and self must be both vertical. Weld puddle must be carefully away from eds and downward or upward from what is specified.
• Overhead is hard due to difficulty to work gravity pull down. Torch points upwards and must be controlled.
• Its preferrable In the work flat or Horizontal welding positions for ease and stability;
• It may be necessarry the perform over head.

Abbreviations for Weld Types and Welding Positions

• Combinations are used together to note weld types together.
• Designations.
• Letters - identify the type of weld. Numbers to indentiy the possition.
• F:filet. G;groove.
• (1)flat or rolled. -2 horizontal, -3 veritical, -4 overhead -5 pipe axis and. 6 - pipe axis incline
• The combination are used in combination. (1G is in floor. 3F is filet (filet with filler))

Combination Fillet-Groove Welds

• Arc welding - single Bevel groove weld Backing and opening and backing referred to as AF assemblage.
• Fill welded - V grove.
• Welded -3G called 3GF and is vertical.

True" Welding Position of Plate and Pipe

• Welds can happen in intermidiate position in actural welding.
• Tables exist with ansgles/ rotations for the position form true. .
• Positions vaiay form flat all position.
• Pipe can vary 0-90 degress .

Considerations in Joint Selection

• Many types of designs are available with various edges with question: how should the joint perform? -BUTT/ CORNER T-JOINT AND LAP - -Wield metal depositon accessibility. Edge Preperations and heat absorbent. -wielding and possiblity. position/ Material thiickness -Prequalited Joints-

4.1 Depositon

-Relation too the direct amount. -increase yield - costs/ residual process and distortion. -Limit it per economic - -slashing can help reduce cost . . -Equal and left needs need weld metal of the right.

4.2 Welding

• The process with most design play a major part. -high heeat input -Single grooves -coating of electric

4.3 Material process

• Thicknesses of metal to select single are part of pre-planning
• Less costly is single but more yield, More process.
• J& V help with access and volume.

Edges

• Dissipation-Considered. Plates Increase increase to make work-an

4.5- Absorbent

Heat Absorption/Capacity for Blevelling. Helps guide for better disperrsment between both sides-

4.6 Groves Shape

• Two way - shape & efficiency.
• -Square with Single vs doube. to help make the seal a good for from oneside/ both..

Groove Root Opening - the Dimensions. Shape Heat is source and the best way to determine is the Welding - and distorsion- if

• Three forms of edes
• V/ & you groves are most common. K and double J- help determine both memebers .

Methods for Preparation

The ease the welder depends on the percision of on the edges and overall accurate fit. Edges need reasonable accuracy. The way the material is set us should be uniform in the joint. Ensure efficient and uniform is input several ways include Metal (machining vs thermal or none)

• Shearing
• Planning
• Sawing
• grinding

51. Machine and Cutting

Sheering is good and Quickest for 2 3/4 (1903mm) Edge free free cracks (excessive Square/ Bevel- (blade to do so) Blade is clean(oil)- surface - contamination / Mitting may work

ADV

• Good
• Clean- good (alum to soft steel.)
• No heat

5.2 Oxy

• Cutting - gougers old time -Safely delivers .fuel -Gases- used and what torches Cutting / heating both are what's. used for this process by the gases that it has fuel Acet(Lye) Propanal Used for the cutting. Can also be used for pre cut. - pre cutting is easier Can cut a lot at a time

Applications of Oxy-Fuel Cutting

• Common process - cut for weld and cut material for demolition.
• Versatile - cuts carbon the range and can structure To prepare
• Square
• Bevel

5.3Preparation. & Edge

The oxy process Carbon ranges is done easily Cutting action ends by pre heating. Correct heat , Scale can remove easy = smoothness

Manual requires high heat, but manual is undesirable Guides are used and help w the torch of oxy The cuts have High defined precise -

5.4. There

Them a Distortion to cut (Gas). Can affect light weights with • Distortion- (min) • Minimize this o Preheat (can) o Inner- make it unattached • Stack- thick easy • Subm • Med steel need hardening to cuts to what is made better o Start with is done to prep

Arc 5.5

C A Air- A ARC Is that that used Common short - is CA but not to the CA process Used and materials

• Can remove metal faster(cut, grind or chip
• Cheep equit
• CA has more than what's allowed It's quick etc