Mar. 19, 2025
Fiberglass-reinforced plastic (FRP) grating is a versatile and durable solution for industrial and commercial applications, including flooring systems, walkways, platforms, stairs, ramps, trench covers, and catwalks. Compared to traditional steel grating, FRP grating offers superior corrosion, moisture, and fire resistance, along with excellent thermal insulation and non-conductive properties. Its lightweight nature makes installation and maintenance more efficient, reducing operational costs over time.
Despite their common benefits, there are key differences between molded and pultruded FRP grating. Understanding these distinctions will help in selecting the right type for specific applications.
Molded FRP grating is typically designed with a square mesh pattern, though rectangular configurations are also available. It is manufactured as a single, seamless panel, eliminating mechanical joints between bearing bars. This enhances its bi-directional strength, allowing it to distribute loads efficiently.
For added safety, molded FRP grating is available with different surface options: a concave meniscus surface or a quartz grit slip-resistant surface. Additionally, covered grating options help prevent objects or liquids from falling through, offering enhanced protection in certain environments.
Molded grating is produced by layering liquid resin and continuous fiberglass rovings within a mold until the desired thickness and dimensions are achieved. After the layers are built up, the mold undergoes a curing process, ensuring the grating's strength and durability.
At Shengfei, we adhere to strict quality control measures, ensuring every molded grating panel delivers exceptional performance. With a high resin-to-glass ratio (approximately 65% resin to 35% glass by weight), our molded grating offers extended service life, even in the most challenging environments.
Unlike molded grating, pultruded FRP grating is constructed using parallel bearing bars with either T- or I-shaped profiles, held together by perpendicular cross-rods. The closer the bearing bars are spaced, the stronger the grating becomes.
Pultruded grating is ideal for applications requiring heavier load-bearing capacity and longer spans. Its continuous fiberglass rovings enhance resistance to tension, compression, and bending forces, providing superior longitudinal strength. Additionally, a continuous glass mat further increases transverse strength and impact resistance.
Pultruded FRP grating undergoes several production steps to ensure maximum strength and consistency:
Step 1: Reinforcement
The process begins with fiberglass reinforcement. Fiberglass rovings provide unidirectional strength, while woven fiberglass mats offer multidirectional reinforcement. These materials are shaped into the desired bearing bar profile.
Step 2: Impregnation and Resin Bath
The fiberglass reinforcements are saturated in a thermoset resin bath—typically polyester or vinyl ester resin—combined with pigments, fillers, and additives for enhanced durability and UV resistance.
Step 3: Surface Veil
A lightweight polyester fabric, known as a surface veil, is added just before entering the heated die. This creates a smooth, resin-rich surface that improves chemical and environmental resistance.
Step 4: Curing and Cutting
The impregnated reinforcements pass through a heated pultrusion die, where the resin undergoes a thermosetting process. This forms a rigid T- or I-shaped bearing bar, which is then cut to the required length.
Step 5: Assembly
Holes are drilled along the length of the bearing bars, allowing for the insertion of cross-rods. These rods are secured with epoxy, creating a strong and stable grating panel.
The primary distinction between molded and pultruded FRP grating lies in the manufacturing process. Molded grating is produced as a single, seamless panel, providing exceptional bi-directional strength and flexibility. Pultruded grating, on the other hand, offers superior load-bearing capacity and extended span capabilities due to its structural reinforcement.
While pultruded grating is stronger and stiffer, molded grating provides greater corrosion resistance, impact resistance, and flexibility. The choice between these two types depends on the specific demands of the application.
Comparison Chart: Molded vs. Pultruded FRP Grating
| Feature | Molded FRP Grating | Pultruded FRP Grating |
|---|---|---|
| Manufacturing Process | Layers of liquid resin and continuous fiberglass rovings are molded into a single, seamless panel. | Continuous glass rovings and cross-rods are pultruded into parallel bearing bars which are then assembled. |
| Strength Orientation | Provides bi-directional strength due to its one-piece construction. | Offers unidirectional strength with enhanced load-bearing capacity along the length. |
| Load Capacity & Span | Ideal for applications with moderate load requirements. | Designed to support heavier loads and longer spans, suitable for demanding applications. |
| Surface Options | Available with a meniscus (concave) or quartz grit slip-resistant finish, with an optional covered surface. | Features a resin-rich smooth surface created by a surface veil for added durability. |
| Structural Characteristics | Exhibits high flexibility, corrosion resistance, and impact resistance without mechanical joints. | Offers consistent strength with excellent resistance to tension, compression, and bending. |
| Application Suitability | Best for environments where flexibility, corrosion, and impact resistance are priorities. | Ideal for heavy-duty industrial and commercial applications requiring extended spans and higher loads. |
Both molded and pultruded FRP grating offer significant advantages over traditional steel grating. When selecting between the two, key factors to consider include load requirements, environmental conditions, and span length.
At Shengfei, we specialize in providing high-quality FRP grating solutions tailored to diverse industrial needs. Contact us today to learn more about our molded and pultruded FRP grating products or to discuss your specific project requirements.
