What Is a Gusset Plate?
A gusset plate is a flat piece of metal used to connect structural members at a joint — where beams meet columns, braces meet chords, or diagonal members intersect within a truss. The plate transfers load between the connected members, keeping the joint stable under both static and dynamic forces.
In construction and mechanical engineering, gusset plates appear in virtually every steel structure: factory buildings, pre-engineered metal buildings, mezzanine floors, equipment frames, pipe racks, solar panel mounting systems, and scaffolding. Despite being a seemingly simple component, the gusset plate is critical to the load-carrying capacity of the entire joint. A bolt hole misaligned by just 1-2mm can cause stress concentration, leading to fatigue cracking over time.
This is precisely why modern gusset plates are fabricated using CNC laser cutting instead of traditional plasma cutting or manual drilling. This guide covers gusset plate types, materials, bolt hole standards, surface treatment, and how we produce them at Laser Tuan Thinh in Binh Duong, Vietnam.
Types of Gusset Plates
Flat Gusset Plate
The simplest form — a flat plate with bolt holes, fastened by bolts to two or more structural members at a joint. Flat gusset plates are typically triangular, rectangular, or custom-shaped depending on the angle between connected members.
Applications: Truss nodes, beam-to-column connections, diagonal brace connections.
Bent Gusset (L-Shape)
A gusset plate bent 90 degrees on a CNC press brake, forming an L-shape. One flange bolts to a horizontal beam, the other to a vertical column — ideal for perpendicular connections.
Applications: Beam-to-column right-angle joints, mezzanine corner brackets, cantilever supports.
Triangular Gusset
Right-triangle or isosceles-triangle shapes used specifically at truss nodes. The hypotenuse is often curved or chamfered to reduce stress concentration at sharp corners.
Applications: Roof truss nodes, bridge trusses, crane truss joints.
Custom-Shape Gusset
When members intersect at non-standard angles, the gusset plate requires a unique shape — trapezoidal, fan-shaped, or freeform. Laser cutting handles any shape from the same CNC program without tooling costs.
Single-Sided vs Double-Sided
- Single-sided: One plate on one side of the joint. Simpler, lower cost, suitable for light to medium loads.
- Double-sided: Two symmetric plates clamping both sides of the joint. Higher load capacity, resists twisting, used for heavy structural connections.
Materials for Gusset Plates
Mild Steel SS400
SS400 (equivalent to Q235, ASTM A36) is the most common material for structural gusset plates worldwide. Low cost, excellent machinability, and easy weldability make it the default choice. After fabrication, SS400 requires surface treatment — either hot-dip galvanizing or primer coating — to protect against corrosion.
Common thicknesses: 6mm, 8mm, 10mm, 12mm, 16mm, 20mm.
| Property | Value |
|---|---|
| Yield strength | ≥ 245 MPa |
| Tensile strength | 400-510 MPa |
| Weldability | Excellent (no preheat needed) |
| Cost | Lowest of all structural metals |
| Corrosion resistance | None without coating |
Stainless Steel SUS304
SUS304 gusset plates are used in environments requiring corrosion resistance — food processing plants, pharmaceutical facilities, outdoor architectural structures, or anywhere aesthetics matter. No painting required; the chromium oxide layer provides self-healing corrosion protection.
Common thicknesses: 3mm, 4mm, 5mm, 6mm, 8mm, 10mm.
| Property | Value |
|---|---|
| Yield strength | ≥ 205 MPa |
| Tensile strength | ≥ 520 MPa |
| Corrosion resistance | Excellent |
| Cost vs SS400 | 3-4x higher |
| Weldability | Good (TIG welding recommended) |
Stainless Steel SUS316
SUS316 contains added molybdenum for superior resistance to saltwater, chloride, and acidic environments. Used for gusset plates in chemical plants, marine structures, and wastewater treatment facilities.
Common thicknesses: 4mm, 6mm, 8mm, 10mm.
Galvanized Steel (SGCC)
Pre-galvanized sheet is used for thinner gusset plates (under 3mm), primarily in racking systems, lightweight frames, and small pipe supports. The factory-applied zinc coating provides built-in corrosion protection for indoor use without additional finishing.
Common thicknesses: 1.5mm, 2.0mm, 2.5mm, 3.0mm.
Material Comparison
| Criteria | SS400 (Mild Steel) | SUS304 | SUS316 | SGCC (Galvanized) |
|---|---|---|---|---|
| Cost | Lowest | High (3-4x) | Very high (5-6x) | Low |
| Corrosion resistance | None (needs coating) | Excellent | Superior | Moderate |
| Typical thickness | 6-20mm | 3-10mm | 4-10mm | 1.5-3mm |
| Welding | Easy (MIG/MAG) | TIG recommended | TIG recommended | Easy |
| Primary use | Structural steel buildings | Food, pharma, architecture | Chemical, marine | Racking, light frames |
Recommendation: For about 80% of structural steel applications, SS400 with hot-dip galvanizing offers the best cost-to-performance ratio. Choose stainless steel only when the environment is corrosive or hygiene standards apply.
Why Laser Cut Gusset Plates?
1. Bolt Hole Accuracy of ±0.1mm
Structural gusset plates demand exact bolt hole positioning. If holes are off by 1-2mm on the job site, installers must ream or enlarge holes — reducing the connection’s shear capacity and delaying construction.
CNC laser cutting positions every hole to ±0.1mm, ensuring bolts slide in cleanly without field modification.
2. Clean Edges With No Burr
Plasma cutting leaves behind burr (sharp ridges) that require manual grinding — time-consuming and inconsistent. Laser cutting produces clean, smooth edges with virtually no secondary finishing. This is especially important for gusset plates destined for hot-dip galvanizing, where burr causes uneven zinc adhesion.
3. Perfect Consistency Across Thousands of Pieces
When a project calls for 500 or 1,000 identical gusset plates, laser cutting guarantees that every single piece is dimensionally identical — same hole positions, same outer dimensions, same tolerances. No cumulative error like manual drilling.
4. Complex Shapes at No Extra Cost
Triangular gussets with chamfered corners, slotted holes, curved edges, or asymmetric layouts — laser cutting handles all of these from one CNC program. No custom jigs, no drill templates, no punching dies.
5. Faster Than Drilling
A gusset plate with 8 bolt holes: manual layout, center-punching, drilling, and reaming takes 15-20 minutes. Laser cutting completes the same plate — full outer profile plus all holes — in under one minute.
Bolt Hole Standards for Gusset Plates
Bolt holes in gusset plates must be larger than the bolt diameter to allow assembly tolerance. Per TCVN 5575:2012 (Vietnamese steel structure design code) and AISC 360 (American standard):
| Bolt Diameter | Standard Hole Diameter | Oversized Hole Diameter |
|---|---|---|
| M8 (8mm) | 9mm | 10mm |
| M10 (10mm) | 11mm | 12mm |
| M12 (12mm) | 14mm | 15mm |
| M16 (16mm) | 18mm | 20mm |
| M20 (20mm) | 22mm | 24mm |
| M22 (22mm) | 24mm | 26mm |
| M24 (24mm) | 26mm | 28mm |
| M27 (27mm) | 30mm | 32mm |
Edge Distance and Hole Spacing
Steel structure codes specify minimum distances to prevent tear-out and ensure load transfer:
- Minimum center-to-center spacing: 2.5 times the hole diameter (e.g., M16 with 18mm hole requires minimum 45mm spacing)
- Minimum edge distance: 1.5 times the hole diameter (e.g., M16 with 18mm hole requires minimum 27mm from hole center to plate edge)
- Maximum center-to-center spacing: 12 times the thickness of the thinnest connected plate, or 200mm — whichever is smaller
Important note for designers: Always dimension actual hole size on your drawings, not the bolt diameter. Send DXF/DWG files with holes drawn at the correct finished size and we will cut to your drawing exactly.
Surface Treatment for Gusset Plates
The right surface treatment depends on operating environment and base material.
Hot-Dip Galvanizing
The most common protection for SS400 gusset plates used outdoors. Plates are immersed in molten zinc at 450 degrees Celsius, depositing a 50-100 micron zinc layer that metallurgically bonds to the steel surface.
Advantages: Complete coverage including inside bolt holes, 15-25 year outdoor lifespan, zero maintenance required.
Fabrication requirements: Edges must be burr-free, vent holes needed on enclosed shapes, surfaces must be clean of oil and mill scale.
Primer and Topcoat Painting
An economical option for mild steel gusset plates used indoors or in dry environments. Process: sandblast or shot-blast surface preparation, epoxy primer, polyurethane or alkyd topcoat.
Advantages: Lower cost than galvanizing, flexible color options.
Limitations: Shorter lifespan (5-10 years), periodic maintenance required, difficult to fully coat inside bolt holes.
Powder Coating
Suitable for thinner gusset plates (under 6mm) used indoors. Process: degrease, phosphate wash, electrostatic powder application, cure at 180-200 degrees Celsius. Produces a durable, uniform, scratch-resistant finish.
Passivation for Stainless Steel
After fabrication, stainless steel gusset plates should be immersed in nitric acid or citric acid solution to restore the protective chromium oxide layer, particularly in heat-affected zones around welds.
Surface Treatment Selection Guide
| Environment | Recommended Material | Surface Treatment |
|---|---|---|
| Indoor, dry | SS400 | Primer + topcoat or powder coat |
| Outdoor, rain/sun | SS400 | Hot-dip galvanizing |
| Humid, salt spray | SUS304 | Passivation |
| Chemical, acidic | SUS316 | Passivation |
| Food, pharmaceutical | SUS304 | Polish + passivation |
Applications
Factory Buildings and Warehouses
Gusset plates are indispensable at every structural joint in steel-framed buildings: column base connections, ridge joints, truss panel points, and purlin clips. A typical 1,000 square meter factory building may require 200 to 500 gusset plates of various sizes.
Mezzanine Floors
Industrial mezzanines in factories and warehouses use L-shaped gussets to connect beams to columns, and flat gussets for diagonal bracing. Load requirements of 500-1,000 kg/m2 demand precise bolt holes and correct material thickness.
Solar Panel Mounting Systems
Rooftop solar installations on factory buildings use small gusset plates (SUS304 or galvanized steel) to secure aluminum rails to existing purlins. Large project volumes — often thousands of pieces per installation — require consistent quality across every plate.
Pipe Racks
In chemical, petrochemical, and oil and gas facilities, pipe racks use thick gusset plates (12-20mm) or SUS316 to connect horizontal runners, vertical columns, and diagonal bracing. Harsh environments demand hot-dip galvanizing or stainless steel.
Equipment Frames and Conveyors
Gusset plates connect machine base frames, conveyor structures, and industrial robot mounting frames. Precise bolt holes are essential for accurate equipment alignment.
Scaffolding and Formwork
Gusset plates in reusable scaffolding systems require standardized pin and bolt holes, uniform thickness, and deburred edges to prevent handling injuries.
Pricing Guide
Gusset plate fabrication cost depends on material, thickness, dimensions, number of holes, and surface finish:
| Gusset Type | Material | Thickness | Approx. Price (VND/piece) |
|---|---|---|---|
| Triangular 100x100mm, 3x M12 holes | SS400 | 8mm | 15,000 - 25,000 |
| Rectangular 150x100mm, 4x M16 holes | SS400 | 10mm | 25,000 - 40,000 |
| Rectangular 200x150mm, 6x M16 holes | SS400 | 12mm | 40,000 - 65,000 |
| Large 300x200mm, 8x M20 holes | SS400 | 16mm | 80,000 - 130,000 |
| Triangular 100x100mm, 3x M12 holes | SUS304 | 6mm | 35,000 - 55,000 |
| Rectangular 200x150mm, 6x M16 holes | SUS304 | 8mm | 80,000 - 130,000 |
| L-bent 90 deg, 150x100x100mm | SS400 | 8mm | 35,000 - 55,000 |
Prices include laser cutting and bolt holes. Hot-dip galvanizing, painting, and CNC bending are priced separately. Volume orders of 100 pieces or more receive a 15-30% discount.
Factors affecting price:
- Material: Stainless steel costs 3-4 times more than mild steel
- Thickness: Thicker plates cut slower and consume more assist gas
- Number of holes: Each additional hole adds cutting time — but far less than drilling
- Shape complexity: Complex shapes cost the same as simple ones (a key advantage of laser cutting)
- Surface treatment: Hot-dip galvanizing adds approximately 8,000-15,000 VND/kg
Frequently Asked Questions
What is the minimum order quantity?
There is no minimum order. We produce from 1 piece for prototyping all the way up to thousands of pieces for large structural projects.
What is the lead time?
- Small orders (under 100 pieces): 3-5 working days (laser cutting only)
- Medium orders (100-500 pieces): 5-10 working days
- Large orders or orders including galvanizing: 10-15 working days
Can you cut 20mm thick steel?
Yes. Our fiber laser system cuts mild steel up to 20mm and stainless steel up to 12mm. For steel thicker than 20mm, we combine CNC plasma cutting for the outer profile with laser-cut bolt holes to maintain hole accuracy.
What drawing format do you need?
Send DXF or DWG files with overall dimensions and hole positions/sizes clearly defined. If you do not have a CAD drawing, a hand sketch with dimensions is fine — our engineers will create the production drawing at no charge.
Do you deliver outside Binh Duong?
We deliver throughout southern Vietnam — Binh Duong, Ho Chi Minh City, Dong Nai, Long An, Ba Ria-Vung Tau. Free delivery within Thu Dau Mot city for orders over 2,000,000 VND.
Why Choose Laser Tuan Thinh for Gusset Plates?
- Precision fiber laser cutting — Tolerances of ±0.1mm on bolt holes, clean burr-free edges
- Heavy-duty CNC press brakes — L-shaped and Z-shaped gussets bent to ±0.5 degree accuracy
- Steel up to 20mm thick — Serving heavy structural steel requirements
- Full in-house process — Cut, bend, weld, galvanize, and paint under one roof
- From 1 piece — No minimum order quantity
- Fast delivery — From 3 working days for urgent orders
Get a Quote for Your Gusset Plates
Send your drawings (DXF, DWG, PDF) or describe dimensions, material, and quantity — we will return a detailed quote within 24 hours.
Contact us now or send files via Zalo.
See also: Laser cutting services | CNC bending services | Laser cutting pricing 2026