First, the core characteristics of 09CrCuSb seamless steel pipe:
(1) Resistance to sulfuric acid dew point corrosion
1) Chemical mechanism: By adding alloying elements such as copper (Cu 0.25-0.45%) and antimony (Sb 0.04-0.10%), a dense oxide film is formed on the steel surface, effectively blocking sulfuric acid corrosion.
2) Application scenarios: Suitable for sulfur-containing flue gas environments such as coal-fired boilers, oil-fired boilers, economizers, and air preheaters, resisting dew point corrosion.
(2) Excellent mechanical properties
1) Strength and plasticity: Tensile strength ≥360MPa, yield strength ≥245MPa, elongation ≥25%, meeting the pressure-bearing and deformation-resistant requirements of equipment.
2) Impact toughness: ≥34J at room temperature (adjusted according to process), adaptable to low-temperature environments.
(3) Multi-media corrosion resistance:
Besides sulfuric acid, it also exhibits strong resistance to chloride ions (Cl⁻), hydrochloric acid (HCl), hydrofluoric acid (HF), and caustic soda (NaOH), making it suitable for complex corrosive environments.
(4) Outstanding economic efficiency:
1) Cost advantage: Lower price than stainless steel (such as 316L), with corrosion resistance exceeding that of ordinary carbon steel, resulting in a life-cycle cost reduction of over 50%.
2) Extended lifespan: Equipment lifespan is extended from 2-3 years for ordinary carbon steel to over 8 years, significantly reducing maintenance costs.

Second, Chemical Composition and Standards of 09CrCuSb Seamless Steel Pipe
Elements and Contents: C: ≤0.12, Si: 0.20-0.40, Mn: 0.35-0.65, Cr: 0.70-1.10, Cu: 0.25-0.45, Sb: 0.04-0.10, P: ≤0.030, S (Impurities)
Standards Implemented
1) Domestic: GB/T 150.2-2011
2) International: Materials with similar performance may correspond to sulfuric acid corrosion-resistant steel in JIS G3119, but there is no directly equivalent grade

Third, Production Process and Quality Control of 09CrCuSb Seamless Steel Pipe
(1) Smelting and Continuous Casting
Refining is carried out using an electric arc furnace or AOD furnace, and the sulfur and phosphorus content is strictly controlled (≤0.030%) to avoid intergranular corrosion. Some enterprises use RH vacuum degassing treatment, with hydrogen content ≤1.5ppm, to reduce the risk of hydrogen-induced cracking.
(2) Hot Rolling and Cold Rolling
Hot Rolling: Three-roll continuous rolling process, billet heated to 1200-1250℃, final rolling temperature 880-900℃, ensuring uniform microstructure.
Cold Rolling: Multi-pass cold rolling combined with intermediate annealing (680-720℃) to eliminate work hardening.
Precision Control: Wall thickness tolerance within ±5% (far exceeding the ±10% standard of GB/T17395).
(3) Heat Treatment
Normalizing + Tempering: Normalizing temperature 900±10℃, holding for 30min/25mm; Tempering temperature 630±10℃, holding for 60min/25mm.
Microstructure Optimization: Obtaining a uniform ferrite + pearlite microstructure, hardness 150-180HB, balancing corrosion resistance and machinability.
(4) Surface Treatment
Pickling and Passivation: Using a nitric acid-hydrofluoric acid mixed solution to remove the oxide layer and form a passivation film. High-end products: Electrolytic polishing or PTFE coating to improve corrosion resistance.

Fourth, Application Areas of 09CrCuSb Seamless Steel Pipes
(1) Power Industry
1) Boiler Air Preheater Cold End Heat Exchanger Tubes: After use in a power plant, the equipment’s lifespan was extended from 2-3 years to over 8 years, and annual maintenance costs were reduced by 60%.
2) Economizers and Chimney Linings: Resistant to sulfur-containing flue gas corrosion, reducing downtime for maintenance.
(2) Petrochemical Industry
1) Condenser Tube Bundles in Sulfur Recovery Units (WSA Process): Under harsh conditions of 8% H₂S concentration and 4% SO₂ concentration, no significant thinning was observed after 5 years of continuous operation.
2) Waste Heat Boilers in Catalytic Cracking Units: Resistant to high-temperature corrosion (long-term operating temperature ≤400℃), ensuring long-term stable operation.
(3) Environmental Engineering
1) Desulfurization Tower Spray System and Flue Gas Heat Exchanger (GGH): Gradually replacing duplex stainless steel, reducing costs by over 40%.
2) Seawater cooling system: Resistant to Cl⁻ corrosion (critical concentration up to 50000mg/L).
(4) Emerging fields
Waste incineration power generation, biomass power generation: Resistant to high-temperature flue gas corrosion, adapting to the needs of emerging environmentally friendly energy.

Fifth, Selection and procurement recommendations for 09CrCuSb seamless steel pipes
(1) Key parameter verification
1) Cu/Sb ratio: The optimal value is 3.5-4.0:1. When it is lower than 0.25%, the corrosion resistance decreases by more than 20%.
2) Inclusion rating: Class B inclusions ≤ 1.5 grade, avoiding crack sources.
3) Heat treatment curve: Confirm the normalizing + tempering process parameters to ensure uniform microstructure.
(2) Cost comparison
1) Unit price: The wholesale price of Φ38×4mm specification ND steel pipe is 8500-9500 yuan/ton, which is about 40% cheaper than 304 stainless steel.
2) Life cycle cost: Although the unit price is higher than that of carbon steel, the extended lifespan and reduced maintenance costs make it more cost-effective overall.