Every weld you will ever lay down fits into one of only five basic joint configurations. The American Welding Society (AWS A3.0) recognizes just five types: butt, lap, tee, corner, and edge. That is the entire set. Whether you are building a trailer frame, patching an automotive panel, or fabricating a storage tank, the joint between your parts is one of these five arrangements. Knowing them by name and understanding what each one demands is the difference between guessing and knowing what you are doing.
Many beginner welders learn to run a bead on flat plate before they ever hear the formal joint names. They can strike an arc and lay a decent fillet, but then they open a set of plans and see “butt joint with V-groove” or “fillet weld on a tee joint” and realize there is a whole vocabulary they missed. This guide fills that gap. Each joint type gets its own section covering the geometry, when to use it, the pros and cons, which welding processes work best, and the specific mistakes beginners make.
By the end of this guide you will be able to look at any welded assembly and identify which joint type you are looking at. You will know what preparation each joint needs, what can go wrong, and how to avoid the most common problems. Welding positions (flat, horizontal, vertical, overhead) are a separate topic we will save for a future guide. Here we focus on joint types only.
IMPORTANT: This guide covers the five basic joint types for educational reference. Structural, load-bearing, pressure-containing, lifting, code-regulated, or safety-critical joints require qualified design under an applicable welding code or engineering standard (such as AWS D1.1, D1.2, D1.6, or ASME Section IX), a qualified welding procedure specification (WPS), and guidance from a qualified welding professional or engineer. The information in this article is a starting point for general fabrication and home-shop work only.
What Are the 5 Basic Joint Types?
The American Welding Society (AWS A3.0) defines five basic joint types based on how the two members are arranged relative to each other. The joint type describes the geometry of the connection. It tells you how the parts are positioned. It does not tell you what kind of weld to use – that is the weld type, which is a separate concept we will clarify in a moment.
Here is the quick reference:
| Joint Type | Configuration | Typical Weld Type | Preparation Level | Strength |
|---|---|---|---|---|
| Butt | Members in the same plane, edge to edge | Groove weld | Highest | High |
| Lap | One member overlaps the other | Fillet weld | Low | Moderate to High |
| Tee | Perpendicular, forming a T shape | Fillet or groove weld | Moderate | High (both sides welded) |
| Corner | Perpendicular, forming an L shape | Fillet or groove weld | Moderate | Moderate |
| Edge | Parallel edges joined | Edge, fillet, or groove weld | Lowest | Low to Moderate |
Joint Type vs. Weld Type: A Critical Distinction
Beginners often mix up these two concepts. The joint type describes how the parts are arranged – two plates overlapping is a lap joint. The weld type describes how you join them – you might use a fillet weld or a groove weld on that lap joint. A tee joint is often welded with a fillet weld, but it can also use a groove weld if full penetration is required. They are two different things. Think of it this way: the joint is the arrangement of the parts; the weld is what holds them together. Getting this distinction straight early will save you confusion down the road.
Here is a more detailed comparison across all five types:
| Joint Type | Pros | Cons | Best Process Fit | Notes |
|---|---|---|---|---|
| Butt | Efficient load transfer, flat surface, inspectable by radiography | Demanding fit-up, edge prep required for thicker materials, distortion along joint line | SAW for heavy plate, GTAW for thin/precision, GMAW and SMAW for general use | Most common joint in plate and pipe welding |
| Lap | Very forgiving fit-up, no edge prep needed, easy to weld | Material overlap adds weight, crevice traps moisture, stress concentration at weld toe | GMAW for thin gauge, FCAW and SMAW for general fabrication | Best choice when fit-up is difficult |
| Tee | Strong in both directions when welded both sides, efficient for T-shaped assemblies | Access limited for both sides, distortion pulls the stem, root fusion hard to inspect | SAW and FCAW for structural, SMAW for field work, GTAW for thin/precision | Common in structural frames and stiffeners |
| Corner | Clean appearance, good for enclosures and boxes, can be ground flush | Inside access may be impossible, single-sided weld leaves internal crevice, distortion closes the angle | GMAW and GTAW for inside welds, SMAW for thicker sections | Outside welds reduce strength if ground flush |
| Edge | Simplest joint, minimal preparation, quick to weld | Lowest load capacity, limited to thin materials, poor inspectability | GMAW and GTAW for thin gauge, resistance spot welding for production | Not for structural or load-bearing applications |
Butt Joint
Geometry and Definition
Per AWS A3.0, a butt joint is “a joint between two members lying approximately in the same plane.” Picture two pieces of plate sitting on a table, edge to edge, with a gap between them. The weld spans that gap, fusing the two pieces together. The members are aligned so that the top surfaces are flush, or close to flush.
Butt joints can be made with square edges (no bevel) when the material is thin, typically up to about 1/8 inch (3 mm). For thicker material, the edges must be prepared with a groove – a V-groove, U-groove, J-groove, or bevel – to ensure the weld reaches the full thickness of the joint. The groove gives the weld access to the root of the joint, which is essential for complete fusion on thicker sections.
When to Use a Butt Joint
Butt joints are the standard choice when you need to join two pieces of similar thickness end to end. They are used for trailer decks, table tops, structural members, and pipe welding (where pipe ends meet). Any application where a flat surface is important favors a butt joint because the members are aligned in the same plane, leaving no step or overlap.
Butt joints are also the preferred choice when maximum strength and efficient load transfer are required. Because the members are aligned, the load passes straight through the weld without changing direction. This direct path makes butt joints the most efficient design for transferring force.
Pros and Cons
On the positive side, butt joints offer the most efficient load transfer since the members are aligned and force travels straight through the weld. They produce a flat surface with no overlap, making them ideal where appearance or clearance matters. They can be inspected by radiography because the flat geometry allows the X-ray or gamma ray to pass through the weld and both members uniformly.
The downsides are real. Butt joints demand good fit-up – gaps cause burn-through on thin material or incomplete fusion on thick material. Edge preparation is required for anything beyond light gauge, which means grinding or machining bevels. The heat input is concentrated along a single line, which can cause significant distortion, especially on long joints. The weld shrinks as it cools, and the two members pull together, often requiring careful sequencing or clamping to keep the assembly flat.
Process Fit and Preparation
All welding processes can handle butt joints. GMAW (MIG) is common for general fabrication. SMAW (stick) is widely used for structural and field butt joints. GTAW (TIG) is preferred for thin material and where appearance matters. SAW (submerged arc) is used for long, heavy plate butt joints in production.
For square edge butt joints (up to approximately 1/8 inch or 3 mm), no beveling is needed. Keep the gap tight – generally less than the electrode diameter or material thickness – to prevent burn-through.
For thicker material, a V-groove is the most common preparation. General starting points include a 60 to 90 degree included angle with a root opening of about 1/16 to 3/32 inch (1.5 to 2.5 mm). These values vary by process, material thickness, and code requirements. For very thick material (over 1/2 inch or 12 mm), a double-V or U-groove reduces the fill volume and balances distortion.
Clean both sides of the joint at least 1 inch from the weld zone. Remove mill scale, rust, oil, and paint.
Common Beginner Mistakes
Too much gap. The most frequent mistake. The arc blows through the gap, causing burn-through on thin material or excessive melt-through on the back side. Keep the gap tight – less than the wire or rod diameter as a rough guide.
No edge prep on thick material. Trying to weld a square edge butt joint on 1/4 inch (6 mm) plate without a bevel. The weld does not fuse at the root. Bevel or chamfer the edges for material over roughly 1/8 inch (3 mm).
Uneven fit-up. Plates are not aligned, creating a step at the joint. The weld pool runs to the low side, leaving the high side with insufficient fill. Clamp and tack carefully to keep the surfaces flush.
Too much heat on thin material. Burn-through. Use lower amperage or voltage settings and move at a steady travel speed. A copper backing bar can help absorb excess heat.
Too little heat on thick material. Lack of fusion at the root of a groove weld. Use appropriate preheat and maintain a hot enough arc to reach the root of the joint.
Lap Joint
Geometry and Definition
Per AWS A3.0, a lap joint is “a joint between two overlapping members.” One piece lies on top of the other, and the weld is deposited along the edge of the overlapping member. The weld is typically a fillet weld, although a groove weld can be used if full penetration is needed.
Lap joints can be single-sided (welded on only one side of the overlap) or double-sided (welded on both sides). Double-sided welding doubles the weld length and balances the load path, reducing the stress concentration at the weld toe.
When to Use a Lap Joint
Lap joints are the most forgiving of the five types. They are the go-to choice for sheet metal, light fabrication, and thin-gauge work where edge preparation is impractical. If you are welding a patch panel, a bracket, or a gusset plate, you are probably using a lap joint.
The overlap gives you natural gap tolerance. If the two pieces do not fit perfectly, the weld sits on top of the top member, and the gap is hidden. This makes lap joints ideal when fit-up is difficult – for example, when repairing automotive body panels or attaching brackets to existing structures.
Lap joints are also useful when joining members of different thicknesses. The thicker member can be on the bottom, and the weld is deposited at the edge of the thinner top member.
Pros and Cons
The forgiving fit-up is the main advantage. No edge preparation is needed. The fillet weld is straightforward to execute, and the overlap distributes heat, reducing the risk of burn-through on thin material compared to a butt joint.
The downsides include less efficient use of material – the overlap adds weight and cost. The crevice between the overlapping members can trap moisture and contaminants, leading to corrosion. Lap joints create a stress concentration at the weld toe because the load path changes direction as it moves from one member to the other. They also use more filler metal than a comparable butt joint and are difficult to inspect radiographically because the overlapping members block the view.
Process Fit and Preparation
GMAW (MIG) is the most common process for lap joints, especially in thin gauge. The forgiving fit-up matches well with MIG’s ability to bridge gaps. SMAW (stick), GTAW (TIG), and FCAW (flux-cored) all work well for lap joints depending on material thickness and application.
No edge preparation is needed for a lap joint. Just clean the overlap area. Remove all rust, paint, oil, and mill scale from the faying surface (the overlapping surface) and from the area where the weld will be deposited. Clean at least 1 inch from the weld zone on both members. For double-sided lap joints, make sure you can access both sides with your torch or electrode holder.
Common Beginner Mistakes
Insufficient overlap. The overlap is too small, which means the weld size is limited and the joint is weaker than it should be. Make sure the overlap is adequate for the required weld size.
Overlap too large. Wastes material and adds unnecessary weight and cost.
Welding only one side when both sides are needed. For structural lap joints or any application where the joint carries load, welding both sides doubles the effective weld length and reduces the stress concentration at the weld toe. Weld both sides if access and design permit.
Not cleaning the faying surface. Dirt, oil, or mill scale trapped between the overlapping members cannot be seen after welding, but they create porosity, lack of fusion, and contamination in the weld. Clean the overlap area thoroughly before welding.
Excessive heat on thin material. Burn-through of the top member at the edge. Use lower settings and move at a steady speed.
Tee Joint
Geometry and Definition
Per AWS A3.0, a tee joint is “a joint between two members approximately perpendicular to each other in the form of a T.” One member (the stem) stands perpendicular to the other (the flange). The weld is typically a fillet weld deposited in the corner where the two members meet. If full penetration is required, a groove weld can be used by beveling the edge of the stem.
Tee joints are the most common joint in structural fabrication. Beams welded to columns, stiffeners welded to webs, and brackets welded to frames are all tee joints.
When to Use a Tee Joint
Use a tee joint any time you have a vertical member meeting a horizontal member in a T shape. Structural frames, trusses, and support structures rely heavily on tee joints. They are also used in fabrication shops to build T-shaped assemblies from flat stock, to add stiffeners or gussets to plates, and to attach brackets to structural members.
Tee joints are efficient for T-shaped and structural assemblies because they allow the stem to transfer load into the flange. When welded on both sides, the joint is strong in both directions and handles balanced loading well.
Pros and Cons
Tee joints are structurally efficient, especially in frames and trusses. When welded on both sides, the joint is balanced and strong in both directions. Simple fillet welds are sufficient for most applications, keeping costs and preparation time low.
The main challenges are access and distortion. Welding both sides of a tee joint means the stem must be accessible from both sides, which can be tight in some assemblies. The stem heats faster than the flange because it has less mass to absorb the heat, which can pull the stem out of perpendicular. The root of the fillet weld in the corner is difficult to inspect for fusion, and lack of fusion at the root is a common defect.
Process Fit and Preparation
SMAW (stick), GMAW (MIG), and FCAW (flux-cored) are common for tee joints in structural and general fabrication. SAW (submerged arc) is used for large structural sections. GTAW (TIG) is appropriate for thin or precision work where heat input needs careful control.
The most common configuration is a square edge tee joint with a fillet weld in the corner. No edge preparation is needed on either member. If a full-penetration groove weld is required, the edge of the stem must be beveled (single-bevel or double-bevel groove).
Clean both members in the weld zone and remove mill scale from the flange surface where the weld will be placed. For full-strength applications, weld both sides of the stem.
Common Beginner Mistakes
Welding only one side. The joint is unbalanced, and the single weld can pull the stem out of perpendicular. Weld both sides when access and design allow.
Undersized fillet weld. The fillet weld leg size is too small for the thickness of the members. The weld must be large enough to carry the load. Follow the design requirements or WPS for fillet weld size.
Slag inclusion at the root. In stick welding, slag can get trapped in the corner of the tee if the arc is not directed properly into the root. Maintain a tight arc and use a slight weave or manipulation to keep the slag floating out behind the puddle.
Lack of fusion at the root. The weld does not fuse into the corner of the tee. Use a technique that directs the arc into the root of the joint, not just onto the surface of the flange or stem.
Distortion from one-sided welding. The single weld pulls the stem out of perpendicular. Use a sequenced welding pattern to balance the heat, or tack the stem slightly past perpendicular to allow for pull.
Corner Joint
Geometry and Definition
Per AWS A3.0, a corner joint is “a joint between two members approximately perpendicular to each other in the form of an L.” A tee joint has the stem meeting the face of the flange. A corner joint has the two members meeting at their edges, forming an L shape or a box corner.
Corner joints can be welded from the inside (the fillet or groove is accessible inside the corner), from the outside (fillet on the corner edge), or both. The choice depends on access, appearance requirements, and the loads the joint must carry.
When to Use a Corner Joint
Corner joints are the standard for box sections, enclosures, electrical panels, and cabinets. Any time you are building a box, a tank corner, a gate frame, or a structural L-shape, you are using a corner joint. They give a clean exterior appearance, especially when the outside weld is ground flush.
Corner joints are also common in light framing for gates, doors, and equipment stands where the joint does not carry heavy structural loads.
Pros and Cons
A well-made corner joint looks clean and professional, especially when the outside weld is ground flush. Inside corner welds are strong because they have good root access and can be made large enough to develop full strength.
The downsides relate to access. The inside of a corner joint may be impossible to reach once the assembly is closed. If you weld only from the outside, the unwelded crevice inside can trap moisture and cause corrosion. Outside corner welds are difficult to inspect for root fusion because the weld is on the outside of the corner. Distortion can pull the corner closed – the weld shrinks and the 90-degree angle becomes less than 90 degrees.
Process Fit and Preparation
Inside corner welds are accessible with most processes. GMAW (MIG) and GTAW (TIG) work well for thin materials. SMAW (stick) and FCAW (flux-cored) are suitable for thicker sections.
Outside corner welds are typically done with GMAW or GTAW for thin materials and SMAW or FCAW for thicker materials. Square edge corner joints work for light gauge (up to about 1/8 inch or 3 mm). For thicker material requiring full penetration, bevel the inside edge of one or both members.
Clean both members and remove mill scale from the weld zone. If welding from the inside, make sure your torch or electrode holder can reach the joint before you close the assembly.
Common Beginner Mistakes
Welding only the outside when inside access is available. The inside weld is generally stronger because it has better root access and can be made larger. Weld the inside when you can reach it.
Incomplete penetration on outside corner weld. The weld runs on the surface of the corner without fusing into the root. This creates a weak joint that can fail at the corner. Use enough heat and proper technique to ensure the weld reaches the root.
Distortion pulling the corner closed. The weld shrinks and pulls the 90-degree corner to less than 90 degrees. Tack the joint slightly open (a degree or two past 90) to compensate. Use clamping and a balanced welding sequence.
Not considering access during design. You design a corner joint and then realize you cannot reach the weld location with your torch or electrode. Plan the welding sequence and access before you tack the assembly together.
Grinding the outside weld flush reduces strength. If you grind the reinforcement off an outside corner weld, you reduce the throat thickness and the joint may be weaker than designed. If appearance matters, plan for a larger weld that can be safely ground flush.
Edge Joint
Geometry and Definition
Per AWS A3.0, an edge joint is “a joint between the edges of two or more parallel members.” The members are aligned with their edges together, and the weld is deposited along the aligned edges, fusing them. This is the simplest joint configuration – the parts sit side by side, and the weld runs along the seam.
Edge joints are most common in sheet metal, light enclosures, and ductwork. They are used where the joint does not carry significant load and where a simple, quick weld is needed.
When to Use an Edge Joint
Use an edge joint when you need to join the edges of thin panels – automotive body panels, light-gauge assemblies, sheet metal enclosures, and duct sections. Edge joints are also used for sealing the edges of two parallel plates and for edge flanging (where one or both edges are flanged and then welded).
Edge joints are the right choice when the joint is not carrying significant structural load. They are the fastest joint to prepare and weld, making them ideal for production work and automated processes like seam welding and resistance spot welding.
Pros and Cons
The simplicity is the biggest advantage. No beveling, no gap control issues, no complex fit-up. Just clean edges, clamp them together, and weld. Edge joints are quick to weld and work well with automated and high-speed processes.
The main limitation is load capacity. Edge joints have the lowest load-carrying capacity of the five basic joint types. The weld cross-section is limited by the thickness of the members, so the joint cannot carry heavy loads. Edge joints are not suitable for structural applications or any joint where significant stress is expected. They are also difficult to inspect – there is limited access to evaluate the fusion at the root of the joint.
Process Fit and Preparation
GMAW (MIG) is the most common process for edge joints in thin gauge. GTAW (TIG) is used for thinner or precision work, especially on stainless steel or aluminum. Resistance spot welding and seam welding are common in production environments for edge joints in sheet metal.
No edge preparation is needed. Just square, clean edges. Grind or cut the edges clean, remove burrs, and clean both edges and the surrounding area. Good clamping is essential – the edges must stay aligned and flush during welding.
Common Beginner Mistakes
Using an edge joint where a lap or butt joint is needed. This is the most critical mistake. Edge joints are not designed for load-bearing applications. If the joint will carry any significant stress, choose a different joint type.
Too much heat (blow-through). The thin edges melt away quickly. Use lower amperage or voltage settings and maintain a steady travel speed.
Poor edge alignment. The two edges must be flush. A step between the edges creates an uneven weld and a weak point. Clamp the edges securely and check alignment before welding.
Insufficient fusion. Too little heat or too fast travel speed results in the weld sitting on top of the edges without fusing into them. The joint looks welded but fails under light load.
Applying edge joints to thick material. Edge joints on thick plate have limited strength because the weld throat is small compared to the member thickness. Use a different joint type for thick material.
Joint Preparation Basics
Good preparation is the foundation of a good weld. The time you spend cleaning, fitting up, and clamping pays back in fewer defects, less rework, and stronger joints. These practices apply across all five joint types.
Cleaning
Contamination is the number one cause of weld defects. Remove oil, grease, paint, rust, and mill scale from the weld zone before you strike an arc. Clean at least 1 inch on each side of the joint, and more if the material is heavily contaminated.
Use the right tool for the material. Grinding and wire brushing work for carbon steel. Stainless steel requires dedicated stainless steel wire brushes – never use a brush that has been used on carbon steel. Aluminum needs aggressive cleaning to remove the oxide layer, using a stainless steel brush or chemical etching.
Quick Prep Checklist
Clean both members 1+ inch from the weld zone
Check fit-up and gap – adjust if needed
Prepare edges (square, bevel, or groove) as required by material thickness
Clamp securely to hold alignment during welding
Tack at both ends of the joint, then add intermediate tacks
Review your edge prep before welding
Fit-Up and Gap Control
Tight fit-up produces better weld quality. Gaps cause burn-through on thin material, incomplete fusion on thick material, and excessive filler metal consumption.
For butt joints, keep the gap as tight as possible. For thin material, the gap should be less than the material thickness. For lap joints, the overlap gives you natural gap tolerance – the weld sits on top of the top member. For tee and corner joints, tight fit-up at the root reduces the risk of lack of fusion.
Use spaced tack welds to hold alignment. Place tacks every 2 to 6 inches depending on material thickness. Distribute tacks evenly to avoid heat buildup in one spot.
Edge Preparation Options
The edge preparation you need depends on material thickness, joint type, and whether full penetration is required.
Square edge. No bevel. Suitable for thin materials, typically up to about 1/8 inch (3 mm). Used for butt, lap, tee, corner, and edge joints.
V-groove. Single-sided bevel on both members, forming a V when butted together. The most common groove preparation for butt joints on plate from about 1/8 to 1/2 inch (3 to 12 mm).
Bevel groove. One member beveled. Used on tee joints and corner joints when full penetration is required.
Double-V. Both sides beveled. Used on thick plate (over 1/2 inch or 12 mm) to reduce fill volume and balance distortion by welding alternately on both sides.
U-groove and J-groove. Curved groove profiles. Used for thick-wall pipe and heavy plate where a V-groove would require too much fill metal.
Root face. A small flat land at the bottom of the groove. Prevents burn-through at the root by providing a small amount of material that the arc must melt through.
| Material Thickness | Joint Type | Prep Method | Notes |
|---|---|---|---|
| Up to 1/8 in (3 mm) | Butt | Square edge | Minimal gap, good fit-up required |
| 1/8 to 1/2 in (3-12 mm) | Butt | V-groove (60-90 degree included angle) | Root opening 1/16-3/32 in (1.5-2.5 mm) typical; values vary by process and code |
| Over 1/2 in (12 mm) | Butt | V-groove, U-groove, or double-V | Root face, root opening, and bevel angle per WPS or code |
| Any | Lap | Square edge | Clean overlap area; no edge prep typically needed |
| Any | Tee | Square edge or bevel on upright member | Bevel upright member if full penetration required |
| Any | Corner | Square edge or bevel | Bevel inside edge if full penetration required |
| Any | Edge | Square edge | Clean edges, good clamping |
These are general starting points. Actual preparation dimensions vary by process, material thickness, welding position, and code requirements. For code work, follow the Welding Procedure Specification (WPS) or applicable standard.
Clamping and Tacking
Use C-clamps, bar clamps, toggle clamps, or welding magnets to hold members in position. The clamp keeps the joint tight and prevents movement during welding.
Tack weld at both ends of the joint first, then add intermediate tacks. On long joints, allow for thermal expansion. Work from the center outward, or use a back-step sequence to manage heat buildup. For thin material, clamps also act as heat sinks, helping to prevent burn-through.
Beginner Mistakes (Cross-Cutting)
Some mistakes show up across all joint types. These are worth calling out separately because they are the most common roadblocks beginners face.
Insufficient cleaning. The number one cause of weld defects. Contaminated joints cause porosity, slag inclusion, and lack of fusion. No matter which joint type you are welding, clean the weld zone thoroughly.
Poor fit-up. Expecting the weld puddle to fill gaps. It does not. The puddle falls through gaps on thin material and fails to bridge them on thick material. Tight fit-up is critical for every joint type.
Wrong joint for the application. Using an edge joint where a butt or lap joint is needed. Each joint type has strengths and appropriate uses. Match the joint to the loading and access requirements.
Confusing joint type with weld type. Thinking a “tee joint” means a “fillet weld.” The joint is how the members are arranged. The weld is how you join them. A tee joint can use a fillet weld or a groove weld depending on the design.
Distortion by Joint Type
Butt joints shorten along the weld line
Lap joints curl at the overlap edge
Tee joints pull the stem out of perpendicular
Corner joints close the angle (less than 90 degrees)
Edge joints have minimal distortion in most applications
Distortion can be managed through clamping, tacking sequence, welding sequence, and heat input control. Do not fight distortion – plan for it.
Not accounting for distortion. All joints distort as the weld cools. The geometry of the joint determines how it distorts. Plan your clamping, tacking, and welding sequence to manage distortion, not just react to it after the weld is done.
Inadequate clamping. The workpiece moves during welding, causing misalignment, gaps, and inconsistent weld quality. Clamp everything before you weld, and check that clamps stay tight as the metal heats and expands.
Safety Notes
Joint preparation creates its own set of hazards. Grinding, cutting, and edge preparation produce sparks, sharp edges, and airborne debris. These safety reminders apply every time you prep a joint.
Wear safety glasses with side shields (ANSI Z87.1) and a face shield when grinding. Grinding sparks and metal chips can cause serious eye injuries. Wear leather gloves and long sleeves – prepared edges are razor sharp, especially beveled or ground edges. Do not run bare hands along prepared edges.
Grinding sparks can travel up to 35 feet. Clear all combustibles from the work area before grinding. Keep a fire extinguisher within reach. Welding spatter and hot slag are also ignition sources. For a full fire safety guide, see our Welding Shop Fire Prevention guide.
When grinding coated materials (painted, galvanized, or plated), the coating releases hazardous dust and fumes. Use local exhaust ventilation or wear appropriate respiratory protection. Never grind coated materials without proper ventilation.
Clamp or secure all workpieces before welding. A workpiece that shifts or falls during welding can cause injury, burns, and poor weld quality. Make sure your setup is stable before you strike an arc.
Safety Reminder: Joint Preparation PPE
Safety glasses with side shields (ANSI Z87.1) and face shield for grinding
Leather gloves and long sleeves for sharp edge protection
Clear combustibles 35 feet from grinding area
Fire extinguisher within reach
Ventilation when grinding coated materials
Secure all workpieces before welding
Which Joint Should I Use?
Need efficient load transfer, a flat surface, and maximum strength? Use a butt joint.
Need forgiving fit-up with no edge prep? Use a lap joint.
Building a T-shaped assembly or structural frame? Use a tee joint.
Making a box, enclosure, or L-shaped frame? Use a corner joint.
Joining thin, non-structural edges quickly? Use an edge joint.
Every project is a combination of these five joint types. Once you know what each one does best, choosing the right joint becomes second nature.
