Alkaline & Acid Corrosion Resistance Of 2205 Stainless Steel Pipe

In order to illustrate the Acid corrosion resistance of 2205 stainless steel in strong acid solutions, Figure 1 shows the corrosion data of sulfuric acid solution.

Figure 1

The medium conditions range from a weakly reducing environment with low acid concentration to a high-concentration oxidizing environment and a medium-concentration strong reducing hot solution.

2205 and 2507 duplex stainless steels are superior to many high-nickel austenitic stainless steels in solutions with an acid concentration of up to about 15%. Duplex steels are superior to 316 or 317 stainless steels in the range of at least 40% acid concentration.

Duplex stainless steel tubes are also useful in this oxidizing acid containing chlorides. The nickel content of the duplex stainless steel pipe is not enough to withstand the strong reducing corrosion of medium-concentration sulfuric acid solution or hydrochloric acid. At the wet/dry interface in an acid-concentrated reducing environment, corrosion, especially ferrite corrosion, starts and progresses rapidly. The oxidation corrosion resistance of duplex stainless steel makes them an excellent candidate material for nitric acid or strong organic acid devices.

Figure 2 shows the corrosion of duplex stainless steel pipes and austenitic stainless steel pipes in a mixture of 50% acetic acid and different contents of formic acid at boiling temperature. Although 304 and 316 stainless steel pipes can be used for strong organic acid media at room temperature and medium temperature, 2205 and other duplex stainless steels are dominant in many processes involving high temperature organic acid media, and because of their resistance to pitting and stress corrosion, It can also be used in halogenated hydrocarbon process media.

Figure 2, Corrosion of duplex stainless steel and austenitic stainless steel in a boiling mixed solution of 50% acetic acid and different types of formic acid (source, Sandvik)

Posted by stainless steel pipe and fittings supplier, KAYSUNS.

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