09CrCuSb Tube

09CrCuSb (ND steel) steel is a kind of sulfuric acid corrosion-resistant steel that has been tested for a long time and has obtained good results after practical use in many industries. Its good corrosion resistance, various physical and chemical performance indicators, and processing performance can fully meet the Design, manufacture, and use requirements. ND steel, namely 09CrCuSb steel, is the most ideal steel for “sulfuric acid low-temperature dew point corrosion resistance” at home and abroad. At the same time, it belongs to low alloy structural steel.

Chemical Composition (%) of 09CrCuSb Tube

Mechanical Properties of 09CrCuSb Tube

Corrosion resistance

In the sulfuric acid of medium temperature and concentration, the ND steel is passivated due to dissolution, and a passivation layer rich in alloying elements such as Cu, Cr, and Sb is formed on the surface of the steel, which has high sulfuric acid corrosion resistance.

- Comparison of corrosion rate between ND steel and other steel grades (70°C-50%H2SO4 solution)

Outside Diameter & Tolerance

Wall Thickness & Tolerance

Specification:

- Outside Diameter: 12mm-177.8mm

- Wall Thickness: 2.2mm-15mm

- Length: 1000-12000mm, such as 3000mm, 4800mm, 12000mm

- Surface Treatment: Black, painting, transparent oil, etc.

- Heat Treatment: Annealed & Normalized

- Delivery status: The steel pipe is delivered in a normalized heat treatment state

- Keywords: 09CrCuSb, ND Steel, Economizer and air preheater, sulfuric acid resistant low-temperature dew point corrosion steel

Application:

- Economizers, air preheaters, heat exchangers, condensing coolers, and evaporators serving in high-sulfur flue gas; coal-fired boilers, oil-fired boilers; heat exchange, smoke pipes, chimneys of electric furnaces, boilers; acid-resistant and heat-resistant structural parts of baking equipment

- 09CrCuSb steel can also be used with hot-rolled steel plates and steel pipes that are resistant to sulfuric acid dew point corrosion.

Advantages: 

- Excellent resistance to sulfuric acid dew point corrosion

- Resistance to chloride ion corrosion

- Low carbon content in steel, and good use effect

- Very high-cost performance

- ND steel has great economic significance, in line with today's high efficiency, longevity, energy saving, Environmental protection, and other "green" concepts and national development policy orientation.

Although ND steel has high corrosion resistance, the use environment of ND steel is quite harsh. The hot side is acidic gas containing SO2 and SO3, and the cold side is low-temperature air or water. Since the rate of steel in different temperatures and concentrations of H2SO4 varies greatly, the corrosion rate is slower at high concentrations, and the corrosion rate increases with the increase in temperature. Especially in the sulfuric acid medium with high temperature and low concentration, its corrosiveness is the largest, so it is required to appropriately increase the medium temperature of the cooling surface as much as possible in the operation of the working conditions. Therefore, the occasions where ND steel is currently used are relatively concentrated (economizers, air pre-heaters, heat exchangers with chloride ions or sulfuric acid media), etc. In addition to acid dew point resistance, ND steel has higher corrosion resistance than 20g in media containing SO42- and Cr.

ND steel needs to be welded with welding wire and ND steel electrode of the same composition. Since the heating furnace, air preheater, and economizer are all manufactured according to the pressure vessel specification, the ND steel electrode used is a low-hydrogen alkaline electrode. At the same time, the surface of the weldment should be cleaned before welding, and the welding wire or electrode should be preheated (150-350°C/h), with a small current and slow cooling. ND steel is welded with electrodes with a diameter of 2.5mm and a diameter of 3mm. The results show that the welding process is simple, the welding surface is smooth, and the slag is easy to remove. 100% X-ray inspection of the butt welded joints is all qualified. The welds welded by the electrode have good resistance to sulfuric acid dew point corrosion.

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