Specifications
A low-alloy ND steel 09CrCuSb resistant to the dew-point corrosion of sulfuric acid for seamless steel pipe, plate, forged part and special welding material is prepared through smelting in ultra high-power electric furnace, refining outside the furnace, vacuum degassing, conticasting and tandem rolling. It features that during the corrosion, a compact passivated film rich in Cr, Cu, Sb and Ti is generated on its surface, so having very high anticorrosion power.
ND steel is a low-alloy structural steel. Compared with other steel types such as low-carbon steel, Corten, CR1A, etc., ND steel has excellent corrosion resistance and mechanical properties.
Pipe Standard: GB 3087, GB 5310
O.D: 12.7mm - 127mm
W.T: 0.9 - 12.7mm
Grade: 09CrCuSb
Process: Hot Finished or Cold Finished
Heat Treatment: Normalized or as per request
Tests: Tension, flattening, flaring, flange, hardness, reverse flattening, and hydrostatic tests
Application: Pressure containing parts, Economizer, APH (Air Preheater) and other corrosion-resistant applications.
Material standards
①GB 150.2-2011 "Pressure Vessel Part 2: Materials"
②NB/T 47019-2011 "Technical conditions for ordering boiler and heat exchanger tubes"
③SH/T 3096-2012 "Principle of Material Selection for High Sulfur Crude Oil Processing Equipment and Pipeline Design"
Composition specification (GB 150.2-2011)
| C | ≤0.12 | Cr | 0.70~1.10 |
| Si | 0.20~0.40 | Cu | 0.25~0.45 |
| Mn | 0.35~0.65 | Sb | 0.04~0.10 |
| P | ≤0.030 | S | ≤0.020 |
Mechanical Property
| Nominal Thickness (mm) | Tensile Strength Rm(MPa) | Yield Strength ReL(MPa) | Elongation A(%) |
| ≤8 | 390~550 | ≥245 | ≥25 |
Corrosion resistance
In sulfuric acid of medium-temperature and medium concentration, ND steel is passivated due to dissolution, and a passivation layer rich in alloy elements such as Cu, Cr, Sb (antimony, sound: tī) is formed on the surface of the steel and has a high Sulfuric acid corrosion resistance.
Corrosion rate comparison between ND steel and other steels (70℃-50% H2SO4 solution)
| Type of Steel | Corrosion Rate mg/(cm2h) | Times |
| ND (09CrCuSb) | 7.3 | 1 |
| A3 (Q235B) | 103.5 | 14.18 |
| CORTEN-A | 63 | 8.63 |
| CR1A | 13.4 | 1.84 |
| 321 | 21.7 | 2.97 |
| S-TEN 1 & 2 | 27.4 | 3.75 |
For the corrosion resistance, GB 150.2-2011 stipulates: The steel pipe shall be tested for corrosion resistance, and one sample shall be taken from each of the two steel pipes in each batch, and each sample shall be a pipe length of 10 mm. Soak in a H2SO4 solution with a mass fraction of 50% at a constant temperature of 70°C (±2°C) for 24 hours. The average value of the corrosion rate of the two samples is not greater than 80g/m2×h or 140g/m2×h, the specific indicators are indicated in the order contract.
Application
ND steel is currently the most ideal steel for "sulfuric acid low-temperature dew point corrosion resistance" at home and abroad, and its seamless steel tubes are widely used in the manufacture of economizers, air preheaters, heat exchangers and evaporations that are used in high sulfur flue gas The device and other equipment are used to resist the dew point corrosion of sulfur-containing flue gas.
