Legrand^®/Cablofil, a pioneer in the development of cable trays, first made a complete study of the metals available in order to create those systems that would be unmatched in economy and strength. Inherent are the problems connected with the environment and its effect on the life of metals, including weathering and corrosion by electro-chemical and chemical attack.

Steel – Hot Dip Galvanized After All Fabrication and Welding
Commercial quality steel is used for this type of coating, which is described below. This steel is either hot rolled, pickled and oiled, or cold rolled, mild carbon steel.

Steel – Mill Galvanized (Pre-Galvanized)
Where heavy zinc coating is not necessary, steel with a continuous hot rolled zinc coating conforming to ASTM specification A653 designation G90 is used. Products made with mill galvanized steel are generally lower in cost than the same products that are hot dip galvanized after fabrication. However, see the limitations under "Finishes" below.

Stainless Steel
18-8 stainless steel type 304 and marine-grade type 316 is available for most Legrand^®/Cablofil products. Certain products such as raceway push clips, Stack-A-Tube yoke clamps, and some hardware items are made only from 18-8 stainless steel. Stainless steel components are compatible for use with hot dip galvanized, mill galvanized, and aluminum products. Complete cable tray systems can be furnished in stainless steel.

Aluminum Alloys
The principal aluminum used for tray side rails, rungs, and channels is extruded, copper-free alloy 6063-T6. This alloy is used for structural members where extreme stiffness and high tensile strength are mechanically required to resist high unit stresses. This is called a "magnesium alloy".

Alloy 5052-H32 is used for components fabricated from sheet (except covers) such as connectors, blind ends, dropouts, etc. This is a "magnesium alloy", copper free, and very compatible with alloy 6063-T6. This alloy possesses excellent characteristics for stamped and formed components.

Alloys 3003 and 3105 are used for aluminum covers. These alloys are very compatible with alloys 6063-T6 and 5052-H32.

Steel – Hot Dip Galvanized After All Fabrication and Welding:
This high-quality coating is created in a multi-step process and applied to the completed product after all fabrication and welding. First the steel is cleaned by immersing it in a caustic dip tank, then pickled, and finally washed. The article is then dipped into a molten zinc bath. All surfaces are thoroughly coated. Hot dip galvanizing after all fabrication and welding is done on Legrand^®/Cablofil products in accordance with ASTM Specification A123. This coating, applied to steel trays, provides greatest protection at lower cost.

Due to the high temperatures associated with the hot dip process, some warping of the metal is common. This occurs most frequently with products having large, flat surfaces such as covers. To minimize warping, Legrand^®/Cablofil uses thicker sheet metal for covers. This does reduce warping, but does not eliminate it.

Mill Galvanized (Pre Galvanized)
This coating is applied onto steel sheets at the mill in accordance with ASTM Specification A653 and results in a coating thickness of 0.90 ounces per square foot total for both sides. This coating adheres tightly to the base metal at bends and compound curves. Being a hot dip coating prior to tray fabrication, and of a controlled thickness about one-third that of hot dip galvanized after fabrication, it is not generally used outdoors. It is not recommended for areas where there is a concentration of moisture and/or chemical deposits. This material gives excellent service in dry, normal, or controlled atmospheres.

Some Helpful Hints On Which Zinc Coating To Select
1. Protection of the base metal is directly proportional to the zinc coating thickness. Hence, thicker coating means longer life. At sheared or punched locations, zinc on mill galvanized steel is wiped down over approximately 1/3 of the metal thickness giving some sacrificial protection in the presence of an electrolyte. On hot dip galvanized after fabrication, all edges are coated but the original cost is higher.
2. The edges of holes in mill galvanized steel will have no coating; however, a small sacrificial protection is afforded by the top and bottom surfaces of the sheet. The hot dip galvanized comment above applies here.
3. If moisture and drippings accumulate, consider hot dip galvanized after fabrication to avoid premature deterioration at those locations.
4. Covers are typically made from mill galvanized steel in order to avoid the poor appearance caused by severe warping of such large flat surfaces when hot dip galvanized after fabrication.

Other Coatings
Occasionally, other highly special coatings are required such as powder coating, epoxy painting, standard painting, primer paint, and others. Legrand^®/Cablofil engineers are available for consultation on these coatings and their application to Legrand^®/Cablofil trays.