Why do steel pool walls rust?
Rust and Corrosion on Stainless Steel Pool Equipment
Stainless steel "stains less", but it is not stain proof. Indoor pool equipment is very often corroded by chloramines and moisture. Let's talk about why.
In this article, we are specifically talking about indoor swimming pool environments and why they destroy metals. And not just in the natatorium itself; we are also talking about rampant corrosion in the pump room and chemical storage rooms. The answer boils down to two factors that accelerate corrosion, even on supposedly corrosion-resistant stainless steel: low pH, and high chlorine/chloride content in the air.
All about Corrosion, Steel in Swimming Pools
Rust is the natural state of iron (ferrous oxide). Rust will occur when an iron containing metal alloy, such as steel, drops below a pH of 8.2 or 8.3. There are rust inhibitors that can combat the pH drop on the surface, preserving the alloy under the surface.
You can tell when the pool light screw goes missing and someone assumes any screw can be put in it’s place. The result is a rusted “regular” screw within hours or days. Iron left exposed to air will corrode and form a flaky orange-red outer layer.
Pool Wall Rust
Vinyl liner swimming pools most commonly are built using galvanized steel wall panels. While some pool kits use a polymer plastic wall kit, the vast majority installed currently in North America use the steel wall design. For the most part the steel walls of your pool will last forever. In over 25 years of building and renovating vinyl liner pools, I have only encountered wall panels so rusted that they needed to be replaced perhaps once or twice...very uncommon.
While the walls in a vinyl liner pool may rust, in almost all cases this level of rust is not enough to structurally compromise the wall itself. The main concern is that the corrosion developing on the wall can be sharp and can be a hazard for your liner.
The Pool Wall Debate – Steel or Polymer
Advantages of Polymer and Steel Walls steel-wall-panel
Steel Wall Pool Advantages – The first advantage is that steel wall pools are typically less expensive than polymer walls. Secondly is that you can backfill after installing the liner with steel walls, but with polymer the backfill should be done before the pool is filled.
Another advantage of the steel wall pools are that they are much stronger than the polymer pools. This is one reason that when a bridge or building is being built they use steel for the structural construction of the project...
A Closer Look at Corrosion in Swimming Pools & Spas
Corrosion is a serious and expensive problem not only for the pool industry but for mankind as a whole. Per the National Association of Corrosion Engineers, the estimated total cost for corrosion damage in the USA for 2016 was 1.1 trillion dollars.
In the pool industry, corrosion destroys heat exchangers, pool lights, niches, ladders and even the rebar that supports the shell. Anyone who has been in the pool industry long enough has seen corrosion damage. The product life of nearly every metal pool component is limited by this problem.
For this reason, I am presenting a three-part series on the subject. The goal is to help the pool professional understand the basics of corrosion from a physics and chemistry point of view so they may limit corrosion for their clients. Part two will cover the different forms of corrosion. The final installment will review corrosion-mitigation techniques.
STEEL vs High-quality polymer
The debate ends when discovering that galvanized walls are temporary construction and will eventually fail due to corrosion and rust.
Q: Why not use the cheaper steel walls?
A: The same reason why most states will not allow galvanized steel to be used in highway culverts, septic systems, and other projects. Soil conditions or having a salt water pool causes the steel to rust and fail.
Q:Steel sounds like it would be strong. Is it?
A: Steel is strong and the name makes us think of I-beams, etc., but pool walls are more accurately called thin sheet metal.