Galvanized Sheet Metal Fabrication in Melbourne
Galvanized sheet metal is a steel or iron product that has a protective zinc coating to prevent rusting. According to the GalvanizeIt! Online Seminar from the American Galvanizers Association, this method provides corrosion protection, durability under harsh conditions, a long lifespan, versatility, availability, and sustainability.
See how sheet metal fabrication shops, achieve galvanized sheet metal for everyday projects, from construction and transportation to agriculture and recreation:
Electrogalvanizing. This process is when a layer of zinc is bonded to stainless steel using electroplating, which is when a fabricator runs a current of electricity through a saline-and-zinc solution with a zinc anode (an electrode through which conventional current flows into a polarized electrical device).
In electrogalvanizing, the polarized electrical device is a steel conductor.
Compared to hot-dip galvanizing, this sheet metal technique offers lower thickness deposits for comparable to increased performance, a broader conversion coating availability for color options, and brighter deposits.
Galvanization (or galvanizing as it is most commonly called in that industry) is the process of applying a protective zinc coating to steel or iron, to prevent rusting. The most common method is hot-dip galvanizing, in which parts are submerged in a bath of molten zinc.
Hot-dip galvanizing. This is the most popular sheet metal technique for galvanization. The process submerges metal parts in a bath of molten zinc to protect the metal and occurs in three different ways:
- The zinc coating, when intact, prevents corrosive substances from reaching the underlying steel or iron.
- It acts as a sacrificial anode, which is the main component of a galvanic cathodic protection (CP) system used to protect buried or submerged metal from corrosion. This means that if the coating is scratched, the exposed steel or iron will be protected by the remaining zinc.
- The zinc protects its base metal by corroding before iron.
Hot-dip galvanizing limits a steel or iron product’s exposure to the natural elements, protecting it from corrosion and oxidation. This sheet metal technique is also economical, can be performed within minutes, and covers hard-to-reach areas of complex product shapes.
Metallic/thermal spraying. Metallic spraying is the process of covering a sheet metal product with a metallic coating using a spray of molten particles.
According to Corrosionpedia, “a convergence of business leadership, modern digital technology and industry publication experience”, fabricators first subject the iron or steel “to a high degree of heat to achieve a molten state. The molten metal is then atomized into small particles and sprayed outward onto a surface.
The molten particles [don’t] heat the surface because the heat of a particle is proportional to its size. On contact, the particle flattens out and adheres to the surface as it hardens.”
Flame and arc spraying are sub-methods of this technique, adding anti-corrosion layers and thermal barriers. Other benefits of metallic/thermal spraying include increased durability, wear resistance, modified electrical properties, and additional protection to damaged materials.
Sherardizing. Also known as vapor or dry galvanization, sherardizing is named after British metallurgist Sherard Osborn Cowper-Coles.
It involves heating steel products up to 932 degrees Fahrenheit in a closed rotating drum that contains metallic zinc dust and potentially an inert filler, such as sand.
At temperatures above 572 degrees Fahrenheit, the zinc dust evaporates and diffuses into the steel substrate forming a diffusion bond.
This method is ideal for small sheet metal parts and parts that require coating of inner surfaces, as the product must be smaller than the rotating drum.
A huge benefit to this sheet metal technique is that no hydrogen is involved. Therefore, hydrogen embrittlement (when steel becomes brittle due to the introduction and subsequent diffusion of hydrogen into the metal) is excluded.
Did you know that galvanization is the process of applying a protective zinc coating to steel or iron to prevent rusting? The most common method in sheet metal fabrication shops is hot-dip galvanizing. This is the process of submerging metal parts in a bath of molten zinc to protect the metal.
This protection occurs in three different ways:
- The zinc coating, when intact, prevents corrosive substances from reaching the underlying steel or iron.
- It acts as a sacrificial anode, which is the main component of a galvanic cathodic protection (CP) system used to protect buried or submerged metal from corrosion. This means that if the coating is scratched, the exposed steel or iron will be protected by the remaining zinc.
- The zinc protects its base metal by corroding before iron.
So, which sheet metal projects require this kind of complex protection process?
Construction projects: Generally, the most common use for sheet metal is for commercial construction projects. However, galvanized sheet metal-specific uses include:
- Awnings
- Balconies
- Building frames
- Canopies
- Ductwork
- Handrails
- Fences
- Industrial walkways
- Ladders
- Staircases
- Street Furniture
- Support Beams
- Verandas
Electronics: Computer casings and precision instruments are made with zinc coating because it’s moisture- and rust-resistant.
Nails, nuts, and bolts: Unfortunately, the hot-dip coating process provides too much fill in the threads of nuts and bolts that are ⅜-inches or smaller, which can reduce the strength.
Instead, electro-galvanizing (which involves electroplating, a process where a current of electricity is run through a saline/zinc solution with a zinc anode and steel conductor) and stainless steel are used. These electro-galvanized nuts and bolts go into light mechanical products, like cars and bicycles.
Piping: Galvanized piping replaced cast iron and lead in cold-water plumbing in the early 20th century. The life expectancy of galvanized plumbing is about 70 years, depending on the region’s impurities in the water supply, proximity to electrical grids, thickness of zinc, and whether the piping was coated on the inside and outside.
To increase the longevity, some galvanized piping were lined with epoxy resin, which is a petroleum-derived material known for its excellent adhesion, chemical and heat resistance, and insulation properties.
After World War II, galvanized pipes were replaced by copper and plastic piping for interior water drinking service in homes, schools, and similar locations. However, galvanized steel pipes are still used for outdoor applications that require the metal’s superior mechanical strength, especially in poor weather.
Playground equipment: Childrens’ play equipment like bicycle racks, jungle gyms, and swingsets are made with galvanized steel because it’s rust-resistant.
Transportation: Cars and aircrafts are large consumers of galvanized steel, as the industries use it for:
- Hoods
- Fenders
- Oil pans
- Parking brakes
- Roofing
- Seating
- Spring housing
Wire rope: Because wire rope is a highly stressed product, the hot-dip coating process can reduce the strength of the steel on a measurable scale due to hydrogen embrittlement. This is when the steel becomes brittle due to the introduction and subsequent diffusion of hydrogen into the metal.
To solve this problem, stainless steel is used for products, such as electric cables, construction binding materials, window locks, and more.
In short, zinc is resistant to corrosion, moisture, rust, and scratches. It protects the metals during transportation, installation, and service (which isn’t required often due to the self-healing abilities of galvanization). From playgrounds and laptops to car and airplanes, these projects would be nothing without hot-dip galvanizing.
Galvanized sheet metal is one of the most requested products from fabrication shops around the world. In fact, according to the American Galvanizers Association, the world produced more than 3.4 million tons of galvanized steel in 2012.
The most common industries are utility, agriculture, construction, bridge and highway, and recreation. These industries require a variety of sheet metal products, including “structurals, fasteners, tubing, pipe, wire, nails, reinforcing steel, weldments, complex fabrications, guardrail, and posts.”
If so many companies want galvanized sheet metal, what’s the big deal? Here are the benefits of this sheet metal product, as explained by the Galvanizers Association of Australia (GAA):
- Galvanization costs less. When it comes to protective coatings for stainless steel, galvanization is one of the least expensive options because it’s not as labor-intensive for a sheet metal fabrication shop.Even if the initial cost of galvanizing is quoted as more expensive than other protective coatings, this sheet metal technique is the best option for most contractor budgets because of its long-term investment.
Unlike other options, galvanized sheet metal in structural members lasts about 50 years in rural environments and 20 to 25 years in severe urban and coastal exposure. Even with a long life expectancy, it requires little to no maintenance, repairs, and/or replacements.
- No time is lost. Part of being a contractor is ensuring that a project remains on schedule and within budget. Galvanized steel allows you to do just that, because galvanized coatings are easily examined by eye, and non-destructive thickness testing methods are used. No time is lost in excessive testing.After examination, skip surface preparation, painting, or further inspection because galvanized structures are ready to go after direct assembly.
Even after the product is assembled, contractors clean the structure only once annually with alkaline water and a soft cloth.
- It’s the toughest protective coating offered. Hot-dip galvanizing, the most popular form of galvanization, is the process of submerging metal parts in a bath of molten zinc to protect the metal. This protection occurs as the intact zinc coating prevents corrosive substances from reaching the underlying steel or iron.The zinc also acts as a sacrificial anode, which is the main component of a galvanic cathodic protection system used to protect buried or submerged metal from corrosion. This means that if the coating is scratched, the exposed steel or iron is protected by the remaining zinc.
Lastly, the zinc protects its base metal by corroding before iron.
This “unique metallurgical structure…gives outstanding resistance to mechanical damage in transport, erection, and service,” according to the GAA. Through every stage, every inch of the sheet metal product is protected, including recesses, sharp corners, and inaccessible areas.
A bonus to buying galvanized steel sheets? A full protective coating is applied within minutes and is independent of weather conditions unlike other coatings.
- Galvanization is sustainable. If you’re a contractor who’s invested in eco-friendly construction practices, this sheet metal technique is what you’re looking for.According to Whirlwind Steel Buildings & Components, a national manufacturer of pre-engineered metal buildings and metal building components in various markets, “The galvanization process uses a molten zinc bath in which the zinc can be used over and over again…with a very minimal amount of waste.
The durability and longevity of…steel building components means less resources will be used to repair and/or replace parts down the road.”
The post Galvanized Sheet Metal Fabrication in Melbourne appeared first on Australian General Engineering.
from Australian General Engineering http://www.austgen.com.au/galvanized-sheet-metal/
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