In the temporary fence industry, galvanized steel is one of the most commonly used materials. You’ve probably seen silver-coloured galvanized fencing around your city, and if you’re in the construction business, chances are you’ve used it on a project. But did you know that there are different kinds of galvanized steel, and how it is finished can affect the durability of your fence panel? Read on to learn the difference between pre-galvanized and hot-dip galvanized steel, and why one is better for temporary fencing.
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Before we get to the difference between pre-galvanizing and hot dip galvanizing, we need to understand what it means to galvanize metal. Galvanization is a process that involves applying a protective coating of zinc to metals like steel or iron. The zinc coating offers protection against rust and corrosion, effectively increasing the durability or longevity of the metal.
Although galvanization won’t prevent corrosion indefinitely, galvanized steel will last much longer than unprotected steel when exposed to the same conditions.
The difference between pre-galvanizing (or “pre-gal”) and hot-dip galvanizing lies in the process. Let’s break the two down.
When steel components are used in the fabrication of a more complex finished product, they may be galvanized before the final product is assembled. This is what is known as pre-galvanization, or “pre-gal”. It may also be called “in-line”, “continuous”, or “mill” galvanizing. Essentially, the steel components – such as sheets or wire – are galvanized using an automated process before they are cut to size.
This automated process will differ depending on the type of component being galvanized. Generally speaking, the steel components are immersed in a “galvanizing bath” of molten zinc for a short period of time. Once the steel is removed from the bath, excess zinc is removed using a mechanical wiper, air knife, or steam. This leaves a relatively thin galvanized coating of zinc.
The batch hot-dip galvanization process involves immersing the entire finished steel product, or “steelwork”, in a bath of pure liquid zinc. This ensures complete coverage of the product, including the inside surfaces of any hollow areas (such as the inside of a tube). Hot dip galvanization also typically results in a thicker zinc coating than pre-galvanization. A metallurgical bond forms between the steel product and the zinc layer, providing protection against corrosion.
If you search for images of hot dipped galvanized steel, you’ll likely find photos of steel products with a unique surface pattern known as spangle. Spangling can develop when the molten zinc, once adhered to the steel, cools below its melting point. Once it reaches this temperature, the randomly arranged atoms of the liquid zinc begin to arrange themselves into an orderly, crystalline pattern.
Spangle can also be caused by trace metals either deliberately added to the liquid zinc, or unintentionally introduced to the galvanizing bath through the process of hot dipping. The idea that spangling is caused by a tainted or “dirty” galvanizing bath has led to the perception that galvanized metals with spangle are inferior than those without. However, spangle is not a reliable indication of the integrity of most galvanized steel products.
The winner in the pre-galvanized vs. hot-dip galvanized debate really depends on your unique requirements and the intended use of the steel. At Modu-Loc, we offer galvanized temporary fence panels for a variety of applications, including construction, special events, outdoor retail and storage spaces, and more.
When it comes to temporary fencing, which is fabricated from several different steel components and is expected to hold up to inclement weather, hot-dip galvanized steel is preferred. Hot-dip galvanized steel is best for temporary fence panels for a couple of reasons.
Dipping the entire steel fence panel in a hot zinc bath ensures that every nook and cranny is coated – including the areas most vulnerable to corrosion. For instance, molten zinc enters the steel tubes which form the frame of the fence, coating them inside and out. This is key as the square tubes experience a lot of wear and tear from the constant insertion and removal of fence bases. Hot dipping the finished fence panel also ensures all of the welds are coated, offering additional protection.
Compare this to the use of pre-galvanized components in a temporary fence structure. If pre-galvanized steel tubes are cut to length during fabrication of the fence panel, this results in an uncoated surface at the cut end which would be prone to corrosion. Similarly, the welds that hold any pre-galvanized wire mesh the fence frame would be unprotected.
As mentioned, pre-galvanized components are usually only immersed in the galvanizing bath for a very short time, resulting in a relatively thin coating. The thicker zinc coating produced by hot dip galvanization offers improved rust and corrosion protection versus pre-galvanization. This is an important quality in a temporary fence panel, as it is most often used outdoors and exposed to snow, ice, rain, and salt.
When steel is hot dip galvanized, the resulting zinc coating is actually comprised of four layers. The topmost layer is the pure zinc coating. The remaining three layers are alloys of zinc and iron, which are harder than the base steel and form a metallurgical bond between the steel and the zinc. This means they become an integral part of the steel instead of just a coating.
This metallurgical bond created by the process of hot dip galvanization holds up better to abrasion than the thin coating created by pre-galvanization. This is crucial given how much abuse and wear and tear a fence panel endures throughout its lifecycle as a rental item. A temporary fence panel is subjected to a significant amount of abrasion through transport, installation, and removal.
This improved durability and longevity is why Modu-Loc chooses to offer hot-dip galvanized steel fence over other kinds of galvanized fence. While we continue to offer our standard steel temporary fence with green powder coating, we have added hot-dip galvanized fence to our inventory for its improved corrosion resistance, especially for those markets that experience severe winter weather.
If you’re someone who rents temporary fencing for short periods of time, the long-term durability of the fence may be of no consequence to you. However, if you need the fence for a particularly long project, you’ll want to consider the galvanization process used on the fence. And if you are planning to buy temporary fencing, you should look for fence that is hot-dip galvanized to ensure optimum durability and longevity.
Due to the age of the homes north of Chicago, galvanized pipes—and other metal pipes—are a common problem. Below is our list of the most frequently asked questions we have received about galvanized pipes.
Galvanized pipes are steel pipes that have been dipped in a protective zinc coating to prevent corrosion and rust. Galvanized piping was commonly installed in homes built before . When it was invented, galvanized pipe was an alternative to lead pipe for water supply lines. Today, however, we have learned that decades of exposure to water will cause galvanized pipes to corrode and rust on the inside.
No piping system lasts forever, but galvanized pipes have a life span of between 40 to 100 years. If your home’s pipes are from the s or earlier, they are likely nearing the end of their functional life span. However, there’s a reason galvanized pipes are no longer used in modern construction: the risk they pose to a home’s water supply and people’s health.
For more hot dip galvanized pipe fittinginformation, please contact us. We will provide professional answers.
By far, the most significant problem related to galvanized pipes is the mineral deposits that accumulate within the piping. Over time, it causes a reduction in water pressure and pollutes your home’s water. And as rust and corrosion deepen, they compromise the piping system’s stability and cause leaks.
As old and corroded galvanized pipes age, they can release accumulated lead into your tap water. That lead can pose significant health concerns, as ingesting too much can result in lead poisoning, and its symptoms include fatigue, headaches, insomnia, nausea, constipation, abdominal pain, and reduced cognitive abilities. High doses of lead are of particular concern with children, as it can hinder their brain development and lead to lifelong health issues.
When first installed, galvanized pipes look like nickel in color. But as they age, galvanized pipes may appear much duller, lighter, or darker, depending on their environment. We’ve also seen homes where the water pipes have been painted, so it can be difficult to tell at first glance.
Do you know that you have galvanized pipes and need them replaced? Call the experts at American Vintage Home at (847) 999- for pipe replacement today!
If you can’t tell by looking at your pipes, there is a quick test to tell if they are galvanized. Simply grab a flathead screwdriver and a strong magnet. Start by finding your water line and scratch the outside of the pipe with the screwdriver.
The scratched area will look like a copper penny. A magnet will NOT stick to it.
The scratched area will appear ivory or white in color. A magnet will NOT stick to it.
The scratched area will have a silver-gray color. A strong magnet will stick to it.
The scratched area will have a dull silver-gray color, and the metal will usually be soft and easy to scratch. A magnet will NOT stick to it. Lead pipes are easy to bend and may be misshapen. If you have lead pipes, we recommend replacement if possible.
Be sure to scratch-test your pipes in multiple areas. It’s not uncommon to have more than one type of piping on your water line.
The galvanized pipes installed on water lines between and were dipped in molten, naturally occurring zinc. Naturally occurring zinc is impure, so these pipes were bathed in zinc that also contained lead and other impurities. The zinc coating elongated the life of the steel pipes but added small amounts of lead and other substances that could harm inhabitants.
Additionally, if your galvanized pipes were ever connected to lead plumbing (including service lines) there is more cause for concern. The corrosion inside galvanized steel pipes could have trapped small pieces of lead. Even if the lead piping was removed years ago, the galvanized steel pipes could still periodically release the trapped lead into the water flow. Chicago didn’t stop using lead pipes for service lines until , and an estimated 400,000 lead service lines are still in use in Chicago alone.
The only way to ensure that lead is not mobilized from plumbing to tap in a given home is to fully replace the galvanized plumbing and any lead service lines.
Due to the restriction of the line, corrosion in galvanized pipes can cause lower water pressure throughout your home.
If some of your taps have low water pressure but others don’t, this could be a symptom of galvanized pipes. Corrosion can build up unevenly. Also, part of the galvanized pipeline could have been replaced in your home but not everywhere.
Galvanized pipes can release iron and cause discoloration. A clear indicator of this is a brown stain on a porcelain sink.
Given enough time, galvanized pipes will rust through and cause more damage to your home.
For a permanent fix, replacing all galvanized pipes is the best option, as it ensures all the rust and lead in the piping system is completely removed. While repiping an entire house is a big project, the payoffs are well worth the investment. The repiping process begins with an inspection to identify any unique problems that should be addressed. A replacement piping material is then selected, typically copper, PVC, or PEX for freshwater lines and ABS or PVC for waste and drain pipes.
After protecting your home from possible damage, qualified plumbers use specialized tools to locate existing pipes, remove them, and replace them with new ones.
Depending on your home’s size, a repiping project can take up to a week to complete. As pertaining to cost, the pipe material you choose and how much piping you need determines the final price. Older and vintage homes often have special considerations, such as plaster walls, that can result in the job taking longer and costing more.
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