Cablofil Catalog - 2024/2025 - B.7

PW LADDER TRAY
METALS
PW from Legrand, 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.
G
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.
M
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 " later on
this page.
L
T
Stainless Steel
18-8 stainless steel type 304 and marine-grade type 316 is available for
most PW products. Certain 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.
A
Aluminum Alloys
The principal aluminum used for tray side rails, rungs, and channels
is extruded, copper-free alloy 6063-T6. The term " copper free "
references the fact that copper is not used as an alloying element which
dramatically improves the corrosion resistance of aluminum. 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 based alloy " .
Alloy 5052-H32 is used for components fabricated from sheet
(except covers) such as connectors, blind ends, dropouts, etc. This
is a magnesium based alloy, often referenced as 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
similar in corrosion resistance to alloys 6063-T6 and 5052-H32.
GE
Geomet
As a part of a sustainability initiative, Legrand has been replacing all
cadmium-coated parts in its PW product line with Geomet coatings.
It is a higher quality alternative to cadmium-coated parts exhibiting
equal corrosion-resistant characteristics and mechanical benefits in
outdoor installations. Geomet is a thin coating best suited for fasteners
and threaded parts requiring high corrosion resistance and conforms
to ASTM F1136. It's resistant to mechanical damage, performs at
temperatures up to 300°C and features a silver metallic finish.
Geomet is a cost-effective alternative to stainless steel hardware
and is recognized by industry experts as a premium alternative to HotDipped
Galvanized or other ZN-AL coatings. Geomet is chromium-free,
contains no toxic metals and has been approved by the EPA, OSHA and
is RoHS compliant. It is a water-based coating that improves worker
safety and contains no harmful VOCs.
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Other Coatings
Occasionally, other highly special coatings are required such as powder
coating, epoxy painting, standard painting, primer paint, and others.
Legrand engineers are available for consultation on these coatings and
their application to PW trays.
FINISHES
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 PW 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, PW 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.
B.7
INTRODUCTION
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Cablofil Catalog - 2024/2025

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