How to Repair Pipe Corrosion

A common question among those building a house or other facility with plumbing is how to repair pipe corrosion, as you want to ensure the longevity of your investment. We will discuss the types of piping and how they prevent certain forms of corrosion. For those who already have piping installed, we will also talk about how to prevent corrosion in items such as copper piping and galvanized zinc piping.

How to Repair Pipe Corrosion

Water Acidity

Abnormal pH scales in your local water that is running through your piping is a common issue that causes corrosion. The pH scales ranges from zero (extremely high acidity) to 14 (extremely high alkalinity); the middle of the scale, 7, is the neutral point.

In copper piping low pH will eat away at your pipes slowly. Whereas, a pH more than 8 forms a thin layer of copper oxide on the walls of the piping. Therefore, this is also a protective barrier for your pipes. Even a single digit change in pH can hold massive changes to your acidity, because a single digit is a tenfold change in acidity. Normal rain has an acidity of 5.6 due to the carbon dioxide picked up in the atmosphere, acid rain has a pH of 3.6.

Oxygenation and Water

Along with pH, there is oxygen levels in the water. Most domestic water systems are in an “open” style, and are always being replenished with fresh oxygenated water. Dissolved air in water consists of abut 30% oxygen and the rest is mostly nitrogen, which isn’t corrosive. Oxygen degrades metals through a chemical process known as oxidation.

This causes metal converting to an oxide that is also known as rust. As the pipe corrodes, the impurities deposit in the water lines, causing encrustation and buildup of minerals. While oxygen content decreases under higher water temperature and higher pressure, it is these higher temperatures and higher pressure conditions that speed up the oxidization process. Corrosion seems to be a lot more noticeable in hot water lines. Water that is moving faster than 4 feet a second tend to cause corrosion, along with abrupt changes in direction of the pipe.

Galvanic Corrosion

When joining metals together that aren’t similar in composition, they start to undergo a galvanic corrosion. While touching, conflicting metals start to give up electrons. Basically, at the point of contact (pipes threaded together) the metal that is giving up electrons will dissolve over time. The most common occurrence of this is when galvanized pipe and copper pipes are connected; copper pipes touch steel studs, or steel pipe hangers.

The effects of galvanic corrosion are limited to the immediate area of contact. The use of dielectric fittings helps stop the problem. However, they don’t repair the resulting thin walled and damaged pipe.

Basic Repair

While your pipes may have already have corrosion, you can still repair them in several ways. You will need to determine the cause of corrosion in your pipes. Items like water chemistry vary from one geographic region or from one water source to the next. The design of piping systems varies from building to building. You will need to determine water velocity, water temperature, and even the metallurgy of the piping. The more traditional methods of how to repair pipe corrosion include the following:

• Chemical flushing of the system
• Spot repairing and replacement
• Redesigning your hot water re-circulation system to keep your water velocity below 4 feet a second for temperatures up to 140 degrees F, if above 140 F flow maximum recommendations are to not go past 3 feet per second
• Remove abrupt changes in piping direction
• De-burr all tube ends before joining
• Ensure all proper soldering joints
• Ensure there are no dissimilar metals or make sure they are isolated
• Spot repair leaks using gear clamps or other temporary devices
• Use a water treatment system to adjust water quality and pH levels
• A drastic measure is to re-pipe the whole building or part that has corrosion

Aluminum and Plastics

We often recommend our aluminum piping. Aluminum piping is an extruded product that is widely common for all types of fabrication, where light weight and corrosion resistance is a priority.

When it comes to water corrosion aluminum piping (like copper) forms an oxide layer immediately. Also, when the layer becomes damaged, it repairs itself almost immediately. Fit to withstand pH levels from 4 to 9, its perfect for house tap water and other water lines.

These are just the basics on how to repair pipe corrosion. We carry all of these products at Bryan Hose, so give us a call and figure out which product is best for you!