On the resistance of 304 stainless steel pipes to chloride corrosion
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Is there a standard for the resistance of 304 stainless steel pipes to chloride corrosion? In other words, are there specific standards that define the criteria for the resistance of 304 stainless steel to chloride ions, so as to determine whether its corrosion resistance meets the required standards?
Looking at the composition, 304 is not resistant to chloride corrosion; 316L, 2205, etc. should be used instead
Reference can be made to DL_712-2000_Guidelines for Material Selection of Condenser Tubes in Thermal Power Plants; the data provided there is quite comprehensive
At the top of page 338 of GB150, it states that for austenitic stainless steel containers, the chloride content in water should be kept at no more than 25 mg/L. GB/T21433 specifies requirements regarding the corrosion resistance of stainless steel.
Tolerance is also related to environmental temperature; the higher the temperature, the lower the tolerance. For 304 steel, under operating conditions at temperatures up to 60°, the concentration shall not exceed 50 PPM; for austenitic stainless steels, the standard specifies a limit of no more than 25 PPM
Will 304 corrode when boiled in saltwater? How soon does corrosion become noticeable? The chloride concentration in the saltwater should be high enough :)
For pipes made of 304 material, the requirement during hydrostatic testing during equipment manufacturing is that the concentration should not exceed 25 mg/L； However, in applications in industrial units, especially with circulating water at temperatures below 45°C, the required control limit for the concentration of circulating water is no more than 700 mg/L ； In other words, the tolerance of 304 material to chloride ions is related to the operating temperature; many of the heat exchange tubes in heat exchangers are made of 304 material, and keeping the chloride ion content at around 500 allows for stable operation over long periods of time.
The requirements regarding stainless steel’s resistance to chloride ions are specified based on the following four most authoritative standard specifications: GB/T150 \"Pressure Vessels\", page 338; \"Selection and Engineering Application of Pipeline Fittings\", page 108; \"Installation Design Manual for Process Pipelines in Petrochemical Plants: Pipeline Fittings\", page 346; and GB/T21433 \"Testing for Intergranular Corrosion Sensitivity in Stainless Steel Pressure Vessels\". According to domestic standard specifications, the chloride ion content in water used with austenitic stainless steel should be kept at no more than 25 mg/L, while foreign standard specifications require that this level not exceed 50 mg/L