Fabrication of various bends in fiberglass cable trays

Fiberglass (FRP/GRP) cable tray bends are fabricated using precise cutting, pultrusion profiles, and specialized fittings to achieve horizontal, vertical, and angled changes while maintaining structural integrity and chemical resistance.

Materials and Properties

Fiberglass cable trays are made from glass fiber-reinforced plastic (FRP/GRP), typically using unsaturated polyester, vinylester, or epoxy resins combined with continuous glass fibers. These materials provide high mechanical strength, chemical resistance, and electrical insulation, making them suitable for industrial and corrosive environments. Pultrusion is the primary manufacturing method, where fibers are pulled through a resin bath and heated die to form consistent profiles that can be cut and bent as needed.

Types of Bends

Horizontal Bends

Used to change the routing direction along the same plane. Common angles include 45° and 90°. Fabrication involves cutting the tray at precise angles and using pre-fabricated horizontal bend fittings to maintain load capacity and alignment.

Vertical Bends

Used to change elevation or route over obstacles. Can be upward or downward. Vertical bends require careful alignment and support spacing to prevent sagging or stress on the fiberglass tray.

Offset Bends

Used to bypass obstructions while maintaining the same horizontal or vertical plane. Fabrication may involve two angled bends connected by a straight section, calculated using standard offset formulas.

Fabrication Techniques

Cutting and Trimming: FRP trays are cut using diamond-tipped saws or abrasive tools to prevent fiber fraying. Fitting Installation: Pre-molded bend fittings, T-pieces, and crossovers are attached using mechanical fasteners or adhesive bonding compatible with the resin type. Support and Spacing: Proper support brackets and hangers are installed at recommended intervals to maintain structural integrity and prevent deflection.

Surface Treatment: Edges may be smoothed or coated to prevent damage to cables and reduce stress concentrations.

Design Considerations

Load Capacity: Ensure bends do not reduce the tray's ability to support cable weight; a minimum safety factor of 1. 5 is recommended. Chemical and Thermal Resistance: Select resin type based on ambient temperature and chemical exposure.

Polyester resins are suitable for weak acids and alkalis, while vinylester resins offer higher chemical and thermal resistance. Compliance: Follow standards such as DIN EN 61537 for cable support systems, ensuring proper spacing, fastening, and environmental protection.

Summary

Fabricating bends in fiberglass cable trays involves selecting the appropriate resin and fiber combination, cutting and shaping the tray, using pre-fabricated fittings, and ensuring proper support. Horizontal, vertical, and offset bends can be achieved while maintaining mechanical strength and chemical resistance, making FRP cable trays ideal for industrial and corrosive environments. Proper planning, calculation, and installation ensure safe and durable cable routing.