To some degree all homes have water pipe corrosion but do you really need a water repipe? Is spot fixing galvanized pipes the right thing to do? Heck, why is this happening in the first place?
Before we can answer that question we think it’s important for the homeowner to understand a bit about why water piping corrodes.
The truth of the matter is most piping both metallic and non metallic corrodes in some way. Yes, even plastics can swell, crack, shrink or stretch but for the sake of this article we’ll stick to metallic pipe corrosion.
Corrosion is deterioration of; in this case metal, as a result of a reaction with its environment. There also happens to be three different kinds of corrosion and they all relate to plumbing pipes.
Chemical – Chemical corrosion occurs when metal reacts with a certain chemical primarily acids such as hydrochloric or sulfuric.
Physical – Physical corrosion can occur because of abrasive action from water simply moving inside of the pipe or it may happen faster if there are suspended solids in the
Physical or Chemical Corrosion. Photo courtesy of Bushman & Associates, Inc., Medina, OH 44256
water. Most physical corrosion occurs in water pipes because of too much velocity in the water piping system. The most common reason for high velocity in a water piping system is undersized pipes.
Electromechanical – This is extremely common in galvanized pipes and is defined as a chemical reaction that involves oxidation and transfer of electrons. Electromechanical corrosion is the most common form of corrosion in galvanized and copper piping for that matter. So let’s take a deeper look. Quite often electrometrical corrosion happens when dissolved oxygen is present in your water and this along with an electrical current leads directly to what causes the rusting of galvanized pipes. As the metal continues to oxidize more and more material flakes off on the inside of the pipe clogging plumbing fixtures and appliances or the inside walls will swell gradually closing off all flow.
The next cause of corrosion on both copper and galvanized piping is electromechanical in nature and it is called corrosion by galvanic action. Simply put, it’s corrosion through electric current conducted by dissimilar metals with some water thrown in the mix. In this case galvanized pipes connected to copper pipes, which leads to…..you guessed it? Water pipe corrosion! The long explanation involves cathodes and anodes and the arrangement of metals in a galvanic series so we aren’t going to make your head explode for giving you the details.
The question remains, if any of these types of corrosions are present do you need a copper repipe? The answer is a resounding YES! Well, “why can’t I just replace the part
Water Pipe Corrosion from Galvanic Action
of the piping or fittings that are bad?”, you ask. That’s a great question and here is part of the answer, in the case of physical corrosion, if the velocity of the water is too high in the water piping system and has lead to pin hole leaks in a spot or two how can a plumbing professional tell you, your water delivery piping is fixed? An Expert Plumber would and could not make that claim. Chances are that if the water piping has corroded enough for a leak in one spot it’s only a matter of time until another breaks loose and hopefully it’s not during the holidays. Upsizing the water piping is also a must.
It is no different in the case of galvanic action. Once present, because of dissimilar metals being used in a series it is always present until you remove all of the galvanized or all of the copper piping. Replacing a section of galvanized with copper and installing a dielectric union to place a barrier between dissimilar metals will not reverse the corrosion that is already present in either the galvanized or copper side. The only benefit to copper is that once the galvanized pipe is removed the erosion process stops with the copper, once the galvanized pipe begins to erode it will continue until replaced.
We hope this article did a little to shed light on water pipe corrosion and the subsequent need for copper repiping. We at Expert Plumbing Service, Inc. are true experts in pipe repair and whole house repiping. We go the extra mile to minimize disruption in your home. We make sure the process is streamlined and efficient from start to finish.
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