At some point in time, every material starts to wear and tear. That is also true for pipes. The laws of thermodynamics state that once work is put into making a pipe, its highly organized structure will only start to deteriorate. There are many forms of deterioration when it comes to pipes. For instance, the structure of pipes can be weakened by corrosion, fatigue, or even thermal stress.
Regardless of what is causing the wear and tear, the pipe structure will eventually fail. Let’s look at some of the factors that influence external pipe corrosion. External pipe erosion happens when the material that creates pipe walls thins out and weakens over a period of time. Here are some factors that influence external pipe corrosion:
Most materials expand and contract when they are heated and cooled simultaneously. Sometimes this stress might not be enough to destroy the structural integrity of a pipe, but when these forces are combined with others, they can have a significant impact on the structure of the pipe. This causes what we know as creep. Creep causes cracks which can then lead to corrosion of the exterior of the pipe. It is important to understand this concept in order to prevent pipe corrosion.
Contact with Other Materials
Another common cause of erosion in pipes is contact with different materials. For instance, a pipe can be placed on top of saddles that are designed to support its weight. While this is useful for support, constant contact with the saddles can result in wear and abrasion, which eventually leads to corrosion. The material on the outside of the pipe starts to get removed, which creates good enough conditions for rust to occur. This is probably the most common cause of exterior corrosion in pipes. To prevent pipe corrosion, you have to minimize metal to metal contact by using proper pipe saddles.
Galvanic corrosion happens when a cathode and an anode are spaced out by an electrolyte. This happens when a pipe and its saddle are separated by drops of water. This is the corrosion that everyone else knows and is familiar with. If, however, pipes are padded and the saddles are designed properly and insulated, moisture will not get into the space between the pipe and the saddle, which will prevent galvanic erosion. Properly designed saddles and pipe wear pads will also prevent metal-to-metal contact. This is all achieved without chemicals, hot work, or straps.
There are several factors that can lead to external pipe corrosion. It’s important to ensure that pipes fitted with wear pads are properly saddled and insulated to prevent exterior pipe corrosion. It is also important to note that you can significantly prevent pipe corrosion with pipe pads.