What is the yellow color on the surface of stainless steel heat exchange tubes? This yellow stain is usually caused by high-temperature oxidation, impurity deposition, or material issues.
High temperature oxidation refers to the thickening of the surface oxide film on stainless steel heat exchange tubes caused by long-term high-temperature operation, forming a yellow or brown oxide layer (commonly seen when 316L material deteriorates or alloy elements are insufficient); Oil stains, scale, or chemical residues react with the surface of stainless steel heat exchange tubes, especially in open flame or oil fume environments where they are more prone to deposition; In addition, water quality is also affected. Calcium and magnesium ions in hard water are prone to form scale when heated, and yellow patches may appear when mixed with impurities.
If the dirt is minor, it can be removed by acid washing. Severe dirt requires the use of specialized cleaning agents or electrolytic polishing.