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solar water heaters, stainless steel water tank selection
2012-06-03 by seoer2

 Stainless steel water tank data should be of sufficient strength and the use of durable, such as antioxidant in order as well as year-round operation in the warm case, anti-erosion can. In addition, metal materials to have good weldability, make the tank easy to manufacture.
The stainless steel is the modern nations of solar water heater tank throughout the information. Stainless steel with excellent strength, ductility, resistance to erosion and welding of thin stainless steel plate welded into the tank, both light and strong, and throughout adopt integrated pressurized and non pressurized solar powered water heater .
A lot of stainless steel types, selected summary of the stainless steel trademarks thinking strength, ductility, weldability, special economic erosion resistance in the chloride ion in water. Generally used in chemical, food industry, kitchen equipment, 304 stainless steel is austenitic stainless steel, strength, excellent plasticity and good weldability. Most of China's non-pressurized water tank is manufactured with 304 stainless steel.
304 stainless steel corrosion resistance in oxidizing acid medium to strong, but point corrosion and stress corrosion in chloride ion in water easily. Steel containing 12% chromium content, because chromium oxidation vivid agile in the surface of the steel and oxygen constitute a dense solid oxygen-rich passive film (Cr2O3), usefully isolated oxygen from penetrating further into. In the air or oxidizing acid (nitric acid), this class of steel anti-average erosion function, does not rust, so called stainless steel. But in the water, especially with high Cl-concentration in the water, destroyed the effect of Cl-ions in some part of the site from the passive film of Cr2O3 incurred by the attack part of the erosion. Be compared with the average erosion (chemical erosion), part of the erosion (electrochemical erosion) speed much faster than risk more often lead to go missing effect.
Into the aqueous media containing Cl-, stainless steel, the most vulnerable to attack the thin part of the erosion of the welding zone, a district with a ban on highly heated to high temperatures, the organization and function deterioration, anti-erosion function is also reduced. The primary use of life of the tank depends on the water tank at the thin links (welding zone) whether the onset of grain boundary erosion, stress corrosion and points (cracks) erosion of a part of the erosion. Experimental seminar marked the crack (point), when water containing the higher concentration of Cl-ions, erosion is the most common attack in the tank erosion.
304 stainless steel special halogen element anion is sensitive to Cl-ions, water Cl - concentration the greater the lower the critical potential of pitting, the more easy to attack the point of erosion. The critical crack erosion potential is lower than the pitting, cracks erosion when the slit exist easier to attack, erosion faster. Therefore, the land to avoid the erosion of the point (crack) is the crucial point of the progress the solar tank to the use of life.