Galvanized Vs. Wrapped Pipe & Corrosion

Galvanized Pipes

• Galvanized iron and steel pipes are used for water lines and plumbing in homes and businesses. The pipes are galvanized by dipping the pipes in a solution that coats the interior and exterior surfaces to help prevent corrosion. The pipes are often buried under the soil, underneath a concrete slab foundation or hidden in wall cavities. In most cases, corrosion begins inside of the pipe, which makes it difficult to detect and correct. The pipes also may develop a pinhole leak on the surface that is too small to see until the pipe springs a leak.

Corrosion and Galvanized Pipes

• Corrosion takes longer to build with galvanized steel pipes than with iron pipes because iron breaks down over time when it is exposed to water and air. The iron will rust, and the rust will invade the water supply to your home, turning the water you use for drinking and bathing brown. Brown water rings and stains on walls and ceilings are often a homeowner’s first alert that galvanized iron pipes have corroded. This is why many people prefer to use galvanized steel pipes for home water systems and plumbing.

Wrapped Pipes

• Pipe manufacturers use wrapping as one method to protect pipes from external corrosion. Wrapping involves encasing the pipe with a plastic material and is most often used when pipes are buried under soil. The plastic wrapping sets up a barrier to prevent moisture from making contact with the exterior of the pipe, thereby slowing and retarding the growth of rust and corrosion. Interior pipes can be wrapped with plastic, cork sheets, foam tubes, foil and insulation materials such as fiberglass. Cork, foam, foil and fiberglass set up a blockade against moisture and insulate the pipes to reduce heat loss during cold weather.

Wrapped Pipes and Corrosion

• When wrapping is effective, it helps prevent corrosion and extend the lifespan of pipes. The key is to inspect the pipes periodically and check the surface areas that are covered by the wrapping. For example, at the first sign of a water spot in a bathroom, the pipes that supply water to the bathroom should be checked for corrosion and leaks. However, if wrapped pipes are underground, inspections are difficult, if not impossible, to perform. A leak is unfortunately the only way you will know when the wrapping has failed and corrosion has advanced to the point where the pipes and the wrapping need to be replaced.

Comparison

• Unwrapped galvanized pipes are likely to corrode faster than wrapped pipes, because unwrapped pipes do not have a barrier to prevent moisture from building up and turning into rust and corrosion. The only advantage to unwrapped pipes is that you can see early warning signs, such as small streams of water on the pipes, because you get a clear view of the entire pipe. Early signs can be hidden from view with wrapped pipes, making it necessary to look under the wrapping from time to time to check wrapped pipes for corrosion.