Page 8 - Corrosion & Harsh Environment Protection

8 Corrosion & Harsh Environment Protection
Stainless Steel
Stainless steel is the household name for metal alloys containing at least 10.5% chromium
and more than 50% iron. It provides one of the most hygienic surfaces, because it is very easy
to clean and its surface has no pores or cracks to harbor bacteria and other impurities.
It resists corrosion, withstands high temperatures and is easily maintained.
Type 304 stainless steel contains primarily iron, chromium and nickel. Sometimes referred to
as marine-grade, Type 316 stainless steel is similar in formula to Type 304, but molybdenum
is added to strengthen the stainless steel against surface pitting and other deterioration.
For electrical conduit systems, stainless steel offers performance that’s hard to match, combining high corrosion and
chemical resistance with strength, durability, ease of installation and low maintenance. Generally speaking, when compared
to using standard galvanized steel conduit in corrosive environments, stainless steel offers three to five times the lifespan
for Type 304 and four to eight times the lifespan for Type 316.
Corrosion-Resistant Materials
PVC-Coated Metals
One method to improve the corrosion resistance of standard galvanized
steel or iron, as well as aluminum, is to coat the metal in PVC (polyvinyl
chloride). Numerous industry standards, including UL6, ANSI C80.1
and NEMA RN-1, cover the manufacture and testing of PVC-coated conduit
systems. Compliance with these standards, combined with installation
by a contractor experienced with the special requirements of working with
PVC-coated conduit, helps to ensure a quality system that will withstand
corrosive environments. In general, PVC-coated metal provides strong
resistance to most chemicals and will typically last nearly twice as long
as standard galvanized steel conduit in corrosive environments.
Non-Metallic Materials
One way to avoid corrosion is to eliminate the use of metal. While complete elimination
of metal is usually not practical in real-world applications, there are plenty of alternative
materials for electrical raceway system components and accessories. These include PVC,
polycarbonate, nylon, fiberglass and others. PVC conduit and fittings provide excellent
protection when wiring systems need to be embedded in concrete, for example.
Because different non-metallic material properties and characteristics vary so widely, you
should always check the specifications of any material you’re considering for compatibility
with the environment in which you’re planning to use it. In addition, most non-metallic
materials have limitations for maximum operating temperature that must be taken into
consideration to avoid softening or melting of components in high heat areas.