How Can Rusting be Prevented Inside the Tank of a Water Heater?

July 18, 2019

Steel and copper hot water tanks corrode when they’re left unadorned. That’s why special coatings are fused to tank metals. True, there’s anodic protection in there, and that metal rod is designed to sacrifice itself. All the same, alloy water heater tanks should be protected. To furnish this shield, this strong interior barrier, different equipment manufacturers have come up with an interesting range of corrosion armouring options.

Glass-Lined Steel Tanks

Patented linings are fused to metal tanks. On the outside, the metal is treated so that it resists rust. A watery trail or steamy exhaust won’t break through this finish. Inside the tank, which is filled with hot water, things are very different. A rust-resistant alloy just isn’t enough, so the inside surfaces are fully sheathed in glass. A furnace has been used somewhere back at the tank manufacturing factory. With a layer of glass powder applied inside the tank, the chamber slides inside the furnace. By the end of the process, that metal tank has gained a fused glass interior coating.

A Twofold Rust Protection System

Then there’s the anode rod. This corrosion protection device has been studied in some detail already, but let’s add this device to a regular hot water heater. If the glass lining in an appliance has small flaws, rust will find its way into those tiny imperfections. By fitting a second line of defence, this likelihood is averted. The anode breaks down instead, then a maintenance technician comes along and replaces the ailing rod. Better yet, by installing a powered anode, there are no material breakdowns to worry about. Consequently, the glass-lined steel jacket, flaws and all, remains rust-free. Of course, if the lining-fusing process was properly quality-controlled, surface imperfections wouldn’t be a problem

The Search for the Ideal Interior

Glass-lined steel is a premier option, then there are special ceramics and enamels, too. Blue silicon or vitreous enamel coatings, porcelain or polymer-based, there are clearly no limits to the metal fusing materials. Only, that’s not quite true. As well as an imperfection-free surface coating, the selected lining also has to fuse fully to a chosen alloy, whether it’s steel or copper. Moreover, that protective jacket should also provide an insulating feature. Well, it’s already performing as a corrosion shielding material, so a modicum of heat loss armouring isn’t too much to ask for at the same time.

Glass or ceramic linings work well as heat loss insulators. Remember, flasks have been using glass for decades to keep beverages hot. However, this is a relatively fragile and brittle material, which is probably why tailor-designed thermoplastics are making inroads here as next-generation hot water heater interior linings.

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