After the hydraulic testing of stainless steel storage tanks, the water inside the tanks must be properly removed

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After a stainless steel storage tank undergoes hydrostatic testing, it is essential to remove any water present inside the tank. Example: A new road tanker designed to carry phosphoric acid leaked as soon as it was filled with acid for the first time and taken on the road. Upon inspection, the composition of the acid was normal, the grade of stainless steel used for manufacturing the tank truck was correct, and the design and manufacturing processes were good; however, there were many small corrosion holes at the bottom of the tank. Analysis: Where lies the problem? It turns out that the tank truck was manufactured in spring, and after completion, it was pressure-tested using local tap water containing 90 ppm of chloride ions. The water was not drained after the pressure test. If the tank truck is put into use soon, a mixture of a small amount of water and phosphoric acid will not cause significant corrosion problems. However, this tank truck manufacturer used it at an automobile exhibition and left it exposed to the scorching summer sun for several months, causing the water in the tank to evaporate and concentrate, which led to pitting corrosion.