THE NEED FOR A CABLE TRAY SYSTEM:
As technology advances, so too does the need for effective support systems. Today, plants and buildings are moving more and more towards automation. Requiring complex system of wiring and cable laying. Old methods of cable management become obsolete under these demanding conditions. 1. Regular inspections must be carried out, & faults located 2. Many entry/exit points are required
3. New cables may need to be installed, and old ones removed 4. Ventilation, essential to power and similar cables, must be provided Today cable trays have become a necessary part of industrial and commercial construction by offering quick, economical and flexible solutions to these problems. Cable trays are capable of supporting all types of wiring: 1. High Voltage Power Lines
2. Power Distribution Cables
3. Sensitive Control Wiring
4. Telecommunication Wiring
5. Optical Cables
Cable Tray Materials:
Most cable tray systems are fabricated from a corrosion-resistant metal (low-carbon steel, stainless steel or an aluminum alloy) or from a metal with a corrosion-resistant finish (zinc or epoxy). • The choice of material for any particular installation depends on the installation environment (corrosion and electrical considerations) and cost.
• Cable trays fabricated of extruded aluminum are often used for their high strength-to-weight ratio, superior resistance to certain corrosive environments, and ease of installation. They also offer the advantages of being light weight (approximately 50% that of a steel tray) and maintenance free, and since aluminum cable trays are non-magnetic, electrical losses are reduced to a minimum.
• Cable tray products are formed from the 6063 series alloys which by design are copper free alloys for marine applications. These alloys contain silicon and magnesium in appropriate proportions to form magnesium silicate, allowing them to be heat treated. These magnesium silicon alloys possess good formability and structural properties, as well as excellent corrosion resistance. • The unusual resistance to corrosion, including weathering, exhibited by aluminum is due to the self-healing aluminum oxide film that protects the surface. Aluminum’s resistance to chemicals in the application environment should be tested before installation.
• Steel cable trays are fabricated from structural quality steels using a continuous roll-formed process. Forming and extrusions increase the mechanical strength.
• The main benefits of steel cable tray are its high strength and low cost. Disadvantages include high weight, low electrical conductivity and relatively poor corrosion resistance. • The rate of corrosion will vary depending on many factors such as the environment, coating or protection applied and the composition of the steel. T&B offers finishes and coatings to improve the corrosion resistance of steel.
These include pre-galvanized, hot dip galvanized (after fabrication), epoxy and special paints. Stainless Steel
• Stainless steel offers high yield strength and high creep strength, at high ambient temperatures. • Stainless steel cable tray is roll-formed from AISI Type 316 stainless steel. • Stainless Steel is resistant to dyestuffs, organic chemicals, and inorganic chemicals at elevated temperatures. Higher levels of chromium and nickel and a reduced level of carbon serve to increase corrosion resistance and facilitate welding. Type 316 includes molybdenum to increase high temperature strength and improve corrosion resistance, especially to chloride and sulfuric acid. Carbon content is reduced to facilitate welding. Finishing of Cable Tray
The most widely used coating for cable tray is galvanizing. It is cost-effective, protects against a wide variety of environ mental chemicals, and is self-healing if an area becomes unprotected through cuts or scratches.