After pressure testing stainless steel storage tanks, make sure to drain all the water
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A stainless steel tank is used to store phosphoric acid, and it leaks when in use. Upon inspection, the composition of the acid was normal, the stainless steel grade selected for manufacturing the storage tank was appropriate, and the design and manufacturing processes were good; however, there were many small corrosion holes at the bottom of the tank. What is the problem? It turns out that after the storage tank is manufactured, it is pressure-tested using local tap water (which contains chloride ions). The water was not drained after the pressure test. If the storage tank is put into use soon, a mixture of a small amount of water and phosphoric acid will not cause significant corrosion problems. However, after this storage tank was manufactured, it was left for several months, causing the water inside to evaporate and concentrate, which led to pitting corrosion.
It proves the saying: Details determine success or failure!
It’s made of 304 stainless steel, right? If so, it’s not surprising that intergranular corrosion occurs
As the water in the tank evaporates and becomes concentrated, the chloride ion concentration increases, leading to pitting corrosion.
Is the effect of chloride ions in water that significant just from a single instance?
No way, is it that serious? ? ? Water is so powerful, but carbon steel tanks also contain a lot of water; the probability isn’t high