What Is Pultruded Fiberglass Square Tubing?
Pultruded fiberglass square tubing is a closed-section composite profile produced by pulling continuous glass fibers and mats through a heated die with thermoset resin. The result is a dimensionally accurate, low-deflection, corrosion-resistant FRP square tube designed for structural loads and rigid framing applications.
Unlike round or rectangular FRP tubes, square tubes offer uniform bending strength in both X- and Y-axes, making them suitable for symmetric load paths, bolted connections and modular construction.
Throughout this page, the terms pultruded fiberglass square tubing, pultruded FRP square tubing, and pultruded FRP square tube refer to the same product category.
Key Features & Product Characteristics
Uniform Wall Strength
Each tube features consistent wall thickness to maintain predictable bending, shear and compression properties across the entire profile.
Excellent Corrosion & UV Resistance
Polyester, vinyl ester, or fire-retardant resin options protect the tubing from chemicals, saltwater, industrial fumes and outdoor degradation.
Lightweight With High Strength-to-Weight Ratio
Approximately 30%–40% the weight of steel, reducing handling costs and easing installation.
Precision Straightness & Dimensional Stability
Pultrusion ensures straight, stable, warp-free geometry suitable for long structural spans and system integration.
Easy to Fabricate
Can be cut, drilled, bonded and bolted using standard tools without spark hazards.
Applications of Pultruded Fiberglass Square Tubing
Industrial & Structural Uses
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Machine guard frames and protective enclosures
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Walkways, rail platforms, mezzanines and access structures
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Pump room & chemical plant frameworks
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Lightweight support frames for OEM equipment
Outdoor & Corrosive Environments
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Cooling tower frameworks
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Coastal and marine structural supports
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Outdoor signage frames and utility racks
Electrical & Non-Magnetic Infrastructure
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Non-conductive work platforms
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Cable tray supports
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Electrical maintenance structures
Modular Construction Systems
Pultruded fiberglass square tubing is widely used with FRP connectors, gusset plates, and bolted assembly systems, enabling quick modular design.
Technical Specifications
Material System
| Property | Typical Value | Test Method |
|---|---|---|
| Fiber Type | E-Glass continuous roving + mats | — |
| Resin Type | Polyester / Vinyl Ester / Fire-Retardant | — |
| Glass Content | 55–65% | ASTM D2584 |
| Density | 1.75–1.90 g/cm³ | ASTM D792 |
Mechanical Properties
| Property | Typical Value | Standard |
|---|---|---|
| Tensile Strength | 200–240 MPa | ASTM D638 |
| Tensile Modulus | 17–24 GPa | ASTM D638 |
| Flexural Strength | 200–260 MPa | ASTM D790 |
| Flexural Modulus | 17–26 GPa | ASTM D790 |
| Compressive Strength | 150–200 MPa | ASTM D695 |
| Shear Strength | 25–35 MPa | ASTM D5379 |
| Service Temperature | −40℃ to +120℃ | — |
Product Data & Technical Documents
Download datasheets, chemical resistance charts, test reports and cutting templates.
Common Sizes of Pultruded Fiberglass Square Tubing
(All are real, industry-standard FRP sizes)
| Outer Size (mm) | Wall Thickness (mm) | Common Lengths |
|---|---|---|
| 25 × 25 | 3.2 | 3 m, 6 m |
| 38 × 38 | 4.8 | 3 m, 6 m |
| 50 × 50 | 4.8 / 6.4 | 3 m, 6 m |
| 64 × 64 | 6.4 | 6 m |
| 75 × 75 | 6.4 / 9.5 | 6 m |
| 100 × 100 | 9.5 | 6 m |
| 125 × 125 | 9.5 / 12.7 | 6 m |
Custom lengths up to 12 meters available upon request.
Advantages of Pultruded Fiberglass Square Tubing
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✔ Corrosion-proof in acids, alkalis, saltwater and industrial gases
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✔ Non-conductive and non-magnetic
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✔ Lightweight, reducing shipping and installation cost
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✔ High stiffness with stable geometry
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✔ No rust, no rot, no moisture absorption
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✔ Low maintenance & long service life
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✔ Compatible with modular FRP systems
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✔ Custom colors, resins and fire-retardant formulas available
Comparison: FRP Square Tubing vs. Steel & Aluminum
| Property | FRP Square Tubing | Steel | Aluminum |
|---|---|---|---|
| Weight | ★ Very light | ✖ Heavy | ★ Light |
| Corrosion Resistance | ★ Excellent | ✖ Poor (needs coating) | ◎ Good |
| Electrical Conductivity | Non-conductive | Conductive | Conductive |
| Maintenance | Very low | High (painting, rust removal) | Medium |
| Flexural Modulus | Moderate | Very high | High |
| Installation | Easy (hand tools) | Requires welding | Requires power tools |
| Long-Term Cost | Low | High | Medium |
FAQ: Pultruded Fiberglass Square Tubing
Q1: Can pultruded FRP square tubing replace steel in structural framing?
Yes. For environments with corrosion, electrical isolation or weight restrictions, FRP is often a superior alternative.
Q2: What is the maximum available length?
Standard lengths are 3 m and 6 m; custom lengths up to 12 m can be produced.
Q3: Can I bond FRP square tubes instead of bolting?
Yes. Epoxy or methyl methacrylate (MMA) adhesives provide strong structural bonds.
Q4: Is this product suitable for outdoor, UV-exposed applications?
Yes. UV-resistant surface veils and coatings ensure long-term stability.
Q5: Are fire-retardant versions available?
Yes. Tubing can be produced to ASTM E84 Class 1 or equivalent standards.
