904L UNS N08904 tube

Applied fieldAlloy 904L is a multi-purpose material can be applied in many industrial :
1. Petroleum, petrochemical equipment, such as the reactor in petrochemical equipment.
2. Sulfuric acid storage and transportation equipment, such as heat exchanger.
3. Power plant flue gas desulphurization equipment, the main parts: the absorption tower, flue , stopping plate, internal part, spray system.
4. The scrubber and the fans in the organic acid treatment system.

Corrosion resistance
In general welding and heat treatment, there will not be carbide precipitation because of the carbon content is very low (0.020% maximum). This eliminates the intergranular corrosion after the welding and heat treatment. Due to high nickel chromium molybdenum content, and copper element, so even if the 904L in reducing environments, such as in sulfuric acid and formic acid can be deactivationcan be deactivation. High nickel content also has a lower corrosion rate in the activity state. In the range of 0 ~ 98% concentration  pure sulfuric acid , 904L of the use of temperature can be as high as 40. In the range of 0 ~ 85% concentration  pure sulfuric acid, its corrosion resistance is very good. In the industrial phosphoric acid production of Wet method,the impurities are strongly influence of corrosion.904L corrosion resistance is better than ordinary stainless steel in all kinds of phosphoric acid.In strong oxidation of nitric acid, 904L lower corrosion resistance compared to non-molybdenum high alloy steel; In the hydrochloric acid, 904L limited to the use of lower concentrations of 1-2%. In this concentration range. 904L corrosion resistance better than generic stainless steel. 904L with a high resistance to pitting, its crevice corrosion resistance are also very good Chloride solution. 904L high nickel content, reducing the corrosion rate in gap and insurface blemish. Ordinary austenitic stainless steel in the temperature higher than 60 , maybe sensitive of the stress corrosion resistance in a rich chloride environment, by increasing the nickel content in stainless steel, can reduce this sensitivity. Due to the high content of nickel, 904L with high stress corrosion cracking capacity in chloride solution, the concentration hydroxid solution and rich sulfureted hydrogen environment.

Metallurgical structure
904L is a fully austenitic organizations, 904L of ferrite and the precipitation of

904L is a very low carbon containing high alloy austenitic stainless steel. The steel designed for the harsh corrosion condition