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Answering your frequently asked questions


Protecting Your Investment Against Corrosion

Solahart's tank technology has evolved over more than forty years of research and development and a substantial investment in production techniques. Every conceivable material has been tried in the quest for a tank technology that will withstand corrosion. Solahart use a ceramic lined tank for the good reason that it provides the best corrosion protection on the market.

What is corrosion?

Corrosion is a chemical change that occurs on the surface of a metal and rusting is the most common example. Few metals ever escape corrosion in water, no matter what their quality, including "stainless" steel. Gold or platinum do not corrode, but their cost and other physical properties make them unsuitable for water storage heaters.

Corrosion begins its destructive process as a result of small flaws in metal surfaces, at weld points, or from stress. We assume that water is not corrosive. This is not the case, and some water supplies are more corrosive than others. Hot water storage systems are not immune from corrosion and the most effective way of dealing with the problem is to fuse the inside of a strong steel storage tank with a ceramic lining. (see also Fact File 005)

Protecting Against Corrosion

Solahart take corrosion protection further by the installation of a simple replaceable component that takes the brunt of any corrosive potential the water may have. By using a bare metal component (known as an "anode") that is more readily corrodible, it protects both the tank and other components such as the booster.

This approach to corrosion protection is employed all over the world where metal objects are immersed in water. Literally billions of dollars invested in ships and oil rigs world wide, are all protected by replaceable anodes, withstanding the harshest of climates and water conditions.

Over time, the anode dissolves, releasing a completely harmless magnesium salt into the water. The life of the anode varies with the quality of the water - it may be five years before replacement, it may be fifteen. Apart from the anode, bare steel is never exposed to water in the system. With some of Solahart's products the minimum life of the anode will extend to twelve years.

There is another advantage with an anode - it is much cheaper and simpler to replace than a complete tank.

Few metals ever escape corrosion in water, no matter what their quality, including "stainless" steel.


The stages of corrosion

1.Initial Pit forms;

2.Autocatalytic process speeds up as concentrated solution becomes more aggressive;

3.Leak occurs as pit breaks through outer surface.

"Under certain conditions, such as chloride containing mediums and stressed structures, stainless steels are less resistant than ordinary structural steel. Stainless steel alloys are more susceptible to intergranular corrosion, stress corrosion cracking and pitting attack than ordinary structural steels."

Excerpt from: "Corrosion Engineering" by M G Fontana & N D Greene (McGraw Hill) Chapter Six.


Anode attached to gas offshore platform under water pylon.


Marine installations worldwide use anodes to protect billiions of dollars of investment.
(Photos courtesy Woodside Offshore Petroleum Pty Ltd.)


Solahart tank production technology is fully automated, but is further enhanced by using a cermic lining.


Estrada do Algueirão,  31-1º  Dto.
2725 Algueirão - Portugal
Tel. (351)  21  922  9540 - Fax (351)  21  921  0418
Email:  solahart@digal.pt