FRP pultruded profiles are continuous composite shapes (I-beam, angle, tube) with high strength-to-weight and corrosion resistance — the handbook covers design and application.
- Best for: structural design with corrosion-free composites
- Use when: framing, supports and non-conductive structures are needed
- Key spec: ISO 9001, standard shapes + custom pultrusion
1. Material Science Fundamentals
FRP pultruded profiles are composite materials consisting of reinforcing fibers (60-75% by weight) embedded in a thermosetting polymer matrix (25-40%). The reinforcing fibers provide strength and stiffness, while the resin matrix transfers loads, protects fibers, and provides environmental resistance. Key fiber types: E-glass (general purpose, 2400 MPa tensile), S-glass (high strength, 3400 MPa), carbon fiber (high modulus, 4900 MPa), and aramid (impact resistant). Standard industrial profiles primarily use E-glass for cost-performance balance.
2. Fiber Architecture & Laminate Design
Pultruded profiles utilize multiple fiber forms to achieve multidirectional strength: unidirectional rovings (0° direction, primary longitudinal strength), continuous strand mat (random orientation, transverse strength and impact resistance), woven roving (bidirectional ±45° for torsional and shear strength), and surface veil (corrosion barrier, 20-30 g/m²). Typical laminate for structural I-beam: 40% unidirectional rovings, 30% continuous strand mat, 25% woven roving, 5% surface veil. Fiber architecture is engineered based on specific load requirements.
3. Resin Matrix Systems
Unsaturated Polyester (UPR): most common, economical, good mechanical properties, moderate corrosion resistance. Isophthalic Polyester: improved corrosion and UV resistance vs orthophthalic. Vinyl Ester (VE): premium corrosion resistance, excellent mechanical retention in chemical environments, higher cost. Phenolic: fire-retardant, low smoke, high temperature resistance, used in transit and mining. Epoxy: highest mechanical performance, excellent adhesion, used in aerospace and high-performance applications. Resin selection is based on chemical environment, temperature, fire rating, and budget.
4. Structural Design Principles
Design of pultruded profile structures follows EUROCOMP (European design code for composite structures), ASCE (American Society of Civil Engineers), and manufacturer design manuals. Key design considerations: allowable stress design (ASD) with safety factors 2.0-3.0, deflection limits (L/180 for floors, L/240 for roofs), buckling analysis for compression members, connection design (bearing, shear, pull-out), thermal effects (expansion/contraction), and creep analysis for long-term loads. Material properties used in design: longitudinal tensile 300-400 MPa, transverse tensile 50-80 MPa, compressive 200-280 MPa, shear 40-60 MPa, elastic modulus 15-25 GPa (longitudinal).
5. Connection Methods & Best Practices
Mechanical fastening: stainless steel bolts (A4-70 grade), washers required to distribute load, minimum edge distance 2.5×bolt diameter, minimum spacing 4×bolt diameter. Adhesive bonding: epoxy adhesives for high-strength permanent joints, surface preparation required (sandblast + solvent wipe), overlap length minimum 4×profile width. Clip connections: stainless steel or FRP clips for grating and platform assembly, allow for disassembly. Hybrid connections: bolt + adhesive for critical load paths. Best practice: avoid through-bolts in high-tension zones, use stainless steel hardware in corrosive environments, design for thermal movement.
Design Standards & Data Basis
All load, span and capacity values in this article are typical/indicative, derived from laboratory tests per NAAMM MBG-01 (FRP Grating Design Manual) methodology. Molded grating values apply a 5:1 factor of safety on ultimate capacity; pultruded grating values apply a 3:1 factor of safety, both measured at static ambient conditions. Impact loads are limited to 50% of stated values; long-term loads require creep adjustment per ASCE Structural Plastics Design Manual. Certified load tables, stamped engineering calculations and third-party test reports are available on request.
For structural sizing of your specific application, contact our engineering team with your load requirements, span and environmental conditions — we provide free structural calculations within 24 hours. Browse our molded grating and pultruded grating product pages for full specifications and resin options.
Model Naming: Thickness x Mesh Reference
ZEALL molded FRP grating is designated by panel thickness x mesh opening. The standard catalog covers four depths (25 / 30 / 38 / 50 mm) and three mesh sizes (38x38, 19x19, 50x50 mm). A typical designation is "38 mm Molded Grating x 38x38 mm mesh" (model code FG-M3838). Common references:
| Model code | Thickness | Mesh | Duty class | Typical use |
|---|---|---|---|---|
| FG-M2538 | 25 mm | 38x38 mm | Light | Drainage covers, light walkways |
| FG-M3038 | 30 mm | 38x38 mm | Medium | General walkways, ramps |
| FG-M3838 | 38 mm | 38x38 mm | Standard | Industrial platforms, standard service |
| FG-M3819 | 38 mm | 19x19 mm | Standard mini-mesh | Tool handling, heel-safe walkways |
| FG-M5038 | 50 mm | 38x38 mm | Heavy | Forklift areas, long spans |
| FG-P5038 | 50 mm I-bar | 38 mm bar spacing | Heavy pultruded | Heavy-duty platforms, truck traffic |
Typical Structural Parameters (I / S / E)
The table below gives typical flexural stiffness ranges for FRP grating profiles. Values are typical per NAAMM MBG-01 and are not a substitute for a certified mill test report. E depends on resin system (isophthalic polyester approx. 10-12 GPa; vinyl ester approx. 12-15 GPa); I and S scale with bar depth and profile shape.
| Profile | E flexural (GPa) | I (cm⁴ / m width) | S (cm³ / m width) |
|---|---|---|---|
| 25 mm molded grid | 10-12 | 2.5-4.0 | 2.0-3.2 |
| 30 mm molded grid | 10-12 | 4.5-7.0 | 3.2-4.8 |
| 38 mm molded grid | 11-13 | 8-13 | 5.0-7.5 |
| 50 mm molded grid | 11-14 | 16-26 | 8.5-13 |
| 50 mm I-bar pultruded | 12-15 | 55-85 | 22-32 |
Typical values per NAAMM MBG-01; certified values per project-specific mill test report on request.
Browse our product pages for full specifications: pultruded profiles.
Frequently Asked Questions
ZeAllgrate (Nantong ZeAll New Materials Co., Ltd.) is a professional FRP/GRP grating manufacturer with 20+ years experience. ISO9001 certified, exporting to 45+ countries. Email [email protected].
