09crcusb (Nd) -Ideal Sulfuric Acid Resistant Low Temperature Dew Point Corrosion Steel

1. ND steel selected for boiler air preheater, gas saving, heat exchanger, condenser cooler, and evaporator

09CrCuSB (enterprise code ND steel) is a steel used for sulfuric acid low-temperature dew point corrosion resistance (ND steel plate, ND steel pipe, 09CrCuSB steel plate, 09CrCuSb steel pipe, etc.)

1995 National Excellent New Product, awarded the Second Prize in Science and Technology by Sinopec and the Ministry of Machinery; Received the Gold Award at the World Expo organized by the National Science and Technology Commission, and was included in the GB150-1998 standard in 1997. In August 1999, it was awarded a technical evaluation certificate by the National Pressure Vessel Committee and the National Technical Supervision Bureau. It has been included in national and industry authoritative standards such as SH/T3096-2001, People's Republic of China/Steel Pressure Vessels GB150-1998, Industrial Internal Standards Q/TDGG0039-2004, etc., which are the main equipment design and material selection guidelines for processing high sulfur crude oil. Widely used in high sulfur flue gas, coal-fired boilers, fuel boilers, economizers, air preheaters, heat exchangers, evaporators and other equipment, as well as various products with certain resistance to sulfuric acid dew point corrosion.

ND steel is currently the most ideal steel for "sulfuric acid low temperature dew point corrosion resistance" both domestically and internationally. The main assessment index for 09CrCuSb (ND steel) seamless steel pipes/plates (soaking in 7050% H2SO4 solution for 24 hours) is that the corrosion rate is not more than 14mg/cm. h. Compared with carbon steel, similar steel imported from Japan, and stainless steel, its corrosion resistance is 1.84 times that of Japanese CR1R steel, 2.97 times that of 1Cr18Ni9 steel, 8.63 times that of Corten steel, and 14.11 times that of Q235 steel.

09CrCuSb (ND steel) steel is used for coal-fired boilers and oil fired boilers; Hot rolled steel plates and pipes with excellent resistance to sulfuric acid dew point corrosion, developed for the purpose of heat exchange, smoke pipes, chimneys, boiler air preheaters, gas saving, heat exchangers, condenser coolers, evaporators, and other purposes of electric furnaces. Its superior resistance to sulfuric acid dew point corrosion and extremely high cost-effectiveness are the best materials that can completely replace stainless steel and surpass stainless steel (in terms of resistance to sulfuric acid dew point corrosion). ND steel has significant economic significance and conforms to today's "green" concepts such as efficiency, longevity, energy conservation, and environmental protection, as well as national development policy guidance.

2. Applications of ND Steel in other areas

Mainly used for: economizers, air preheaters, heat exchangers and evaporators in high sulfur flue gas, chimney steel sleeves to resist condensation corrosion of sulfur flue gas. Has excellent resistance to sulfur ions, hydrochloric acid and other acidic corrosion. Acid resistant steel is currently the most ideal steel for "sulfuric acid low temperature dew point corrosion resistance" both domestically and internationally.

In industries such as power, metallurgy, and petrochemicals, flue gas treatment systems using coal or heavy oil as the main fuel, such as air preheaters, economizers, flues, chimneys, and desulfurization devices in low-temperature areas of boilers, commonly encounter equipment corrosion problems caused by high sulfur content in the fuel, which forms sulfuric acid at dew point temperature. This is called "sulfuric acid dew point corrosion". Boiler flue gas using high sulfur content fuel contains SO2 and SO3, which combine with water vapor in the flue gas to form sulfite and sulfuric acid, and condense on low-temperature components of the boiler, causing sulfuric acid dew point corrosion. Low temperature components of boilers made of ordinary carbon steel have poor resistance to sulfuric acid dew point corrosion, resulting in severe corrosion. The service life is very short. If acid resistant stainless steel is used to make low-temperature components for boilers, the material price is several times that of ordinary carbon steel, The cost of engineering construction will significantly increase. Therefore, the research, development, and use of low alloy sulfuric acid dew point corrosion resistant steel are of great significance in improving the service life of steel sleeve chimneys, low-temperature components of boilers, and reducing material costs. 

3. The properties of ND steel

National Standard of the People's Republic of China for Steel Pressure Vessels GB150-1998

The technical requirements and usage regulations for H409CrCuSb (ND steel) seamless steel pipes resistant to sulfuric acid dew point corrosion are as follows:

a) The chemical composition (melting analysis) of steel is regulated by H4.

b) The mechanical properties of steel pipes shall be in accordance with the provisions of Table H5.

c) Steel pipes should undergo acid corrosion resistance tests, with one sample taken from each batch of three steel pipes, each of which is a 10mm long steel pipe.

Soak the sample in a 50% H2SO4 solution at a constant temperature of 70 +2C for 24 hours. The average corrosion rate of each sample shall not exceed 8.14 or 14mg/cm-h. The specific indicators shall be specified in the purchase contract.

The conventional mechanical properties of 09CrCuSb (ND steel) steel with good sulfuric acid corrosion resistance are similar to those of 20-GB3087. Comparison of mechanical properties between 09CrCuSb steel and 20 steel. In order to improve their sulfuric acid corrosion resistance, Cr (0.70% -1.10%) added also improves the steel's performance at higher temperatures. GB150-1998 specifies that the service temperature of 09CrCuSb (ND steel) steel can reach 400 , and the good elongation ensures that the steel pipe has good plasticity during bending processing. At the same time, 09CrCuSb (ND steel) steel also guarantees various process properties when supplied, including conducting a water pressure test of 20MPa one by one (20-GB3087 is 10MPa) and eddy current or ultrasonic testing (20-GB3087 is generally eddy current testing), with an outer diameter of 22-400mm. Perform flattening tests on steel pipes (identical to the requirements of 20-GB3087), etc.

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d) Other technical requirements for steel pipes shall comply with the provisions of GB9948.

e) The design pressure of steel pipes for pressure components is p ≤ 6.4Mpa.

f) The operating temperature of steel pipes is 0-400 .

g) The allowable stress of steel pipes shall be in accordance with the provisions of Table H6.

4. Comparison with other grade

09CrCuSb (ND steel) is currently the most ideal steel for "sulfuric acid low temperature dew point corrosion resistance" both domestically and internationally. 09CrCuSB (ND steel) seamless steel pipes are widely used in the manufacturing of coal-fired boilers and fuel boilers that serve in high sulfur flue gas; The heat exchange, smoke pipes, chimneys, boiler air preheaters, economizers, heat exchangers, condenser coolers, evaporators and other equipment of electric furnaces are used to resist the corrosion of sulfur-containing smoke dew points. ND steel also has strong corrosion resistance to nitrogen ions, including hydrochloric acid (HC), hydrofluoric acid (IF), caustic soda (NaOFHD, NaCl), and others. The main reference index of 09CrCuSb (ND steel) steel pipe (soaked in a 50% H2SO4 solution at 70 degrees Celsius for 24 hours) is that the corrosion rate is not more than 14mg/cm-h. Compared with carbon steel, similar steel imported from Japan, and stainless steel, the corrosion resistance of these steel grades is higher. The product has been widely praised and achieved good results after being used in major refineries, power plants, and manufacturing units both domestically and internationally. The specific data is shown in the table below:

5. Results after practical application

After using ND steel, Jinan Refinery saves 3.15 million yuan in annual expenses, while Jinzhou Petrochemical Company saves 1.35 million yuan annually. The use of ND steel not only saves expenses, but also ensures the safe operation of equipment and reduces environmental pollution. Its social benefits are enormous.

6. Conclusion

09CrCuSb (ND steel) is a sulfuric acid corrosion resistant steel that has undergone long-term testing and has achieved good results in practical use in many industries. Its excellent corrosion resistance, various physical and chemical performance indicators, and processing performance can fully meet the requirements of design, manufacturing, and use.

At the same time, 09crcusb (ND steel) has strong corrosion resistance to hydrochloric acid (HCl), hydrofluoric acid (HIF), caustic soda (NaOFH), and sodium chloride (NaCl).