Due to the age of the homes north of Chicago, galvanized 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 1960. 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 1960s 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.
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) 999-4595 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 1880 and 1960 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 1986, 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.
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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.
If you want to replace your galvanized pipes, lead service line, or find out more about your options, we would be happy to help. Call American Vintage Home at (847) 999-4595 or contact us online today to schedule an appointment.
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SCHEDULE NOWAnother aspect of hot-dip galvanizing is proven durability. Hot-dip galvanized steel has been specified extensively in petro-chemical, industrial, power/utility, and bridge/highway projects because of its unmatched durability in these harsh environments. Hot-dip galvanizing remains durable thanks to its abrasion resistance, uniform protection, and complete coverage.
A unique characteristic of the hot-dip galvanized coating is the development of metallurgically bonded (~3,600 psi), abrasion resistant intermetallic layers. The photomicrograph (below) is a cross-section of a galvanized steel coating showing the three intermetallic layers (Gamma, Delta, and Zeta) and top layer of pure zinc (Eta). During the galvanizing process, these layers develop naturally during a metallurgical reaction between the iron in the steel and zinc in the kettle. As the photomicrograph also shows the hardness of each of the layers as a Diamond Pyramid Number (DPN), you can see the three intermetallic layers are harder than the base steel, while the eta layer has ductility which makes damaging the HDG coating very difficult.
Hot-dip galvanizing’s abrasion resistance provides unmatched protection against damage caused by rough handling during transport and erection, as well as in service. Other coatings with lower bond strengths (300-600 psi) can be easily damaged during shipment and construction, weakening their effectiveness, as barrier protection is dependent upon the integrity of the coating.
Same thickness at edge/corner coating grows perpendicular to the surfaceDuring the metallurgical diffusion reaction in the galvanizing kettle, the galvanized coating grows perpendicular to all surfaces. Therefore, the coating is naturally as thick on corners and edges as flat surfaces. Since coating damage commonly occurs at edges, added protection at these junctures is important. Brush- or spray-applied coatings have a natural tendency to thin at corners and edges leaving the part prone to attack. The uniform protection of hot-dip galvanized steel leaves no weak points for accelerated corrosion.
Furthermore, hot-dip galvanizing is a total immersion process, meaning the steel is fully submerged into cleaning solutions and the molten zinc, coating all interior and exterior surfaces. This complete coverage ensures even the insides of hollow and tubular structures and the threads of fasteners are coated. As corrosion tends to occur at an increased rate on the inside of hollow structures where humidity and condensation occur, interior coverage is very beneficial. Hollow structures that are painted have no corrosion protection on the inside. Fully coating fasteners is equally important as they are utilized at connection points which are critical to structural integrity.
Hot-dip galvanized steel is often utilized in some of the harshest environments imaginable, yet it provides maintenance-free longevity for decades. The corrosion resistance of hot-dip galvanizing varies according to its surrounding environments, but generally corrodes at a rate of 1/30 of bare steel in the same environment. Measurements of the actual consumption rate of the coating during the first few years of service provide good data for projecting a conservative estimate for the remaining life to first maintenance, because as zinc corrosion products build on the surface, which in most environments are adherent and fairly insoluble, the corrosion rate often slows as time progresses.
Whether exposed in the atmosphere, subjected to blazing UV rays, snow, and/or other elements, submerged in water, or embedded in soil or concrete, hot-dip galvanized steel can withstand the different corrosive elements and fulfill the intended design life. More information about hot-dip galvanized steel’s longevity can be found in the AGA’s publication Performance of Hot-Dip Galvanized Steel Products.
The most common exposure environment for hot-dip galvanized steel is atmospheric. As hot-dip galvanized steel is exposed to the atmosphere, the zinc interacts with free flowing air and moisture to develop the zinc patina. The zinc patina is critical to the longevity of galvanized steel in the atmosphere; and thus, accelerated, salt-spray tests that do not mimic real world exposure conditions are not an accurate predictor of HDG’s longevity.
The performance of atmospherically exposed hot-dip galvanized steel depends on five main factors: temperature, humidity, rainfall, sulfur dioxide (pollution) concentration in the air, and air salinity. None of these factors can be singled out as the main contributor to zinc corrosion, but they all play a role in determining the corrosion protection hot-dip galvanized (zinc) coatings can provide in certain atmospheric conditions.
For nearly a century, independent and industry testing of samples in five environments (industrial, rural, suburban, tropical marine, and temperate marine) have yielded real-world performance data for hot-dip galvanized steel. Using this real-world corrosion data, statistical methods, and neural network technology, Dr. Gregory Zhang of Teck Metals Ltd. Developed the Zinc Coating Life Predictor (ZCLP) to estimate the life of hot-dip galvanized coatings in atmospheric conditions. Using the ZCLP, you can input specific parameters for any environment and get an estimated time to first maintenance (TFM) for the galvanized coating
Time to first maintenance is defined as 5% rusting of the base steel surface, which means 95% of the zinc coating is still intact, and an initial maintenance is recommended to extend the life of the structure. According to ASTM A123, the governing specification for hot-dip galvanizing, steel ¼-inch thick or greater must have at least 3.9 mils of zinc on the surface, but more often than not, there will be greater than the minimum requirement. Therefore, using the TFM chart, hot-dip galvanized structural steel (>1/4-inch thick) provides 72-73 years of life to first maintenance even in the most corrosive atmosphere, industrial.
The Bridges of Stark County Ohio are galvanized bridges and have been for 40 years. In the early 1970s, Rich Larocco was a young bridge engineer for Stark County, just out of college. At that time, 110 of Stark Countys bridges were deficient and 50% of the bridge budget was used to repaint bridges. Rich worked with the former owner of the galvanizing facility to change those numbers. Rich decided rather than continue to repaint bridges over and over, he would dismantle the bridge. He had the decks and beams removed. The beams were sandblasted and galvanized. Then the entire recycled bridge was reinstalled. After that they never repainted an old bridge or painted a new bridge even if the long beams or large trusses had to be progressively dipped in the galvanizing plant. There are 442 Bridges in Stark County, 335 of which are maintained by the county. Many are short span low clearance steel bridges over creeks and streams in rural areas, making an ideal environment for hot-dip galvanized bridges.
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