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    Standard&Tailormade Stainless Steel Solution


    Product Detailed Location:Home>>Products>>Applications&S... > Prodct Detailed

    Chemistry Industry

    Chemical Industry

    1.Application in sulfoacid industry and sulfoacid medium.
    Corrosion of sulfoacid is connected with its concentration. Sulfoacid with low and medium concentration have comparatively low oxidizability, and belong to reducing acid; while the high concentration sulfoacid has strong oxidizability, and belongs to oxidizing acid. According to such characteristic of sulfoacid, different grades of stainless steel should be used in sulfoacid with different concentration and different temperature. 

    In the process of producing high concentration sulfoacid, cast iron and bricks are often chosen, while stainless steel is not often used for lack of corrosion resistance. In recent years, due to strict control to environmental pollution and for the purpose of improving production environment, there is the trend for the cast iron rack pipe to be substituted by the plate type heat exchanger in the sulfoacid production. For high concentration sulfoacid
    93%-98%, high silicon austenite stainless steel containing molybdenum is often chosen, like SS-920. When temperature is above 130, in the 93%-98%H2SO, corrosion of SS-920 is less than 0.1mm/a, but such steel is not resistant to corrosion by low and medium concentration sulfoacid, and special attention should be paid during the operation. For high concentration sulfoacid under the temperature of 80, acid resistant pump is often made of high silicon nickel-base alloy, like IlliumG, when temperature is higher, 1N504 alloy can be used. 80Ni-9.5Si-3Mo-2.5Cu-3Ti.

    In the medium concentration sulfoacid, common stainless steel does not possess satisfying corrosion resistance, under the temperature of 80
    , high quality Austenite stainless steel that contains molybdenum or copper, like 00Cr20Ni29Mo3Cu4Nb and 00Cr20Ni25Mo4.5Cu, etc is often used.

    Application range of stainless steel in sulfoacid

    Steel type

    Range of temperature and concentration

    < 66(Temperature) Concentration range

    93(Temperature) Concentration range

    1Cr17、0Cr18Ni9、0Cr18Ni10Ti、

    < 0.5%

    < 0.1%

    -

    0Cr18Ni11Nb

    > 90%

    > 95%

    -

    0Cr25Ni20(Nb)、2Cr25N

    < 5%

    < 1.0%

    < 0.01%

    > 90%

    > 95%

    0Cr17Ni12Mo2,0Cr19Ni13Mo3

    < 20%

    < 5%

    < 0.5%

    > 90%

    > 95%


    When sulfoacid contains enough oxygen or oxidant, application range of stainless steel can be extended, e.g.: in sulfoacid below the concentration of 65%, the 18-8 type Cr-Ni stainless steel commonly cannot be chosen, but when sulfoacid contains ≥5%HNO3, such steel can be used. In producing ammonium sulfate, crystallizing tank is commonly made of 0Cr17Ni12Mo2, when chromic salts exist, storage tank and pump can also be made of 0Cr18Ni9.

     


    Introduction Details

    2.Nitric Acid Industry.
    Stainless steel has good corrosion resistance in nitric acid, thus it is widely used in manufacturing equipments for producing nitric acid or that will contact with nitric acid.
    In nitric acid producing technique of high pressure process, 00Cr19Ni10, 00Cr18Ni10Ti and 00Cr18Ni11Nb are used widely. Absorbing towers all use 00Cr19Ni10, ammonia-air mixer uses 00Cr19Ni10, waste gas burner uses 00Cr18Ni11Nb
    ,0Cr25Ni20(Nb). High speed moving parts of air compressor can use 1Cr17Ni2 Martensitic stainless steel.

    In nitric acid with an azeotropy concentration above 68.4%, the conventional 18-8 Type Cr-Ni Austenite stainless steel does not have satisfying corrosion resistance. When there is concentration ≤85%, 0Cr25Ni20 stainless steel is used, in the nitric acid above the concentration or that contains Cr+6, then the high silicon austenite stainless steel with different silicon content, like the 1Cr17Ni11Si4AlTi, 00Cr14Ni14Si4(Ti), and Cr-Ni stainless steel with the silicon content of 5%-6% can be used.

    3.Phosphoric Acid.
    The phosphoric acid with dry process does not contain impurity that enhances corrodibility, and can use 18-8 Type Cr-Ni stainless steel or Cr-Ni stainless steel that contains Mo as material, different grades should be chosen according to the requirements of corrosion resistance.

    Phosphoric acid with wet process is basic material for making phosphatic fertilizer, it is a sort of 54% P2O2 phosphoric acid that contains impunities, Cl-, F-, SO4- particles in the medium have increased its corrodibility, the main technique equipments are commonly made of t rubber lining, lining bricks, graphite, etc, but some heat exchangers and pumps use high-Cr-content super austenite stainless steel, like 00Cr27Ni31Mo3Cu to make the evaporator, substituting original heat exchanger made of graphite, and 0Cr20Ni29Mo3CuNb is used to make the pumps. 

    4.Chlorin & Alkali Industry.
    The main representative product of caustic alkali is NaOH, in the technique environment of producing NaOH, producing equipments are mainly made of synthetic resin, carbon steel, cast iron, Ti, Ni, etc, stainless steel with Ni<40% may have caustic stress corrosion breach, and is commonly inapplicable. In producing NaOH with diaphragm process, content of impurities in the alkali is comparatively higher, especially NaClO3, this will cause intensified corrosion to the conventional nickel material, under such condition, the high purity and high chromium ferritic stainless steel
    00Cr26Mo1,00Cr30Mo2has qualities of excellent regular-corrosion resistance and excellent caustic stress corrosion resistance, thus it can substitute nickel in the manufacture of high temperature concentrating technique equipments.

    In the environment of Chlorine and hydrogen chloride above the temperature of 200
    , the stainless steel has good corrosion resistance, and can deal with the “sparkling” phenomenal, in the dry chlorine and hydrogen chloride gas, the temperature limits for the use of stainless steel are as the follows: 

    Operation temperature of stainless steel in dry chlorine and hydrogen chloride gas

    Name of material

    Upper temperature limit for continuous operation, ℃

    Cl2

    HCl

    Carbon steel

    204

    260

    Carbon steel

    177

    204

    0Cr17Ni12Mo2

    316

    427

    0Cr18Ni9

    343

    399


    When carbonizer tower of soda ash (ammonium chloride) is cooled by sea water, 00Cr18Ni18Mo5 is ammonium chloride corrosion resistant and sea water corrosion resistant, thus carbonizer tower made of this steel has a use life of more than 20 years, besides, as the corrosion can be less, and the impurities are reduced, the level of the product is promoted.

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