First, what are the material properties and chemical composition of SA335P92 steel pipes?
SA335P92 is a high-performance martensitic heat-resistant steel, belonging to the P92 grade in the ASTM A335/A335M standard, mainly used in high-temperature and high-pressure environments.
1) The chemical composition of SA335P92 steel pipes is optimized based on P91, with core improvements including:
Chromium: 8.5-9.5%, forming a dense oxide film and enhancing corrosion resistance.
Tungsten: 1.5-2.0%, significantly improving high-temperature strength above 600℃, with creep strength increased by approximately 30% compared to P91.
Molybdenum: 0.3-0.6%, synergistically enhancing creep resistance with tungsten.
Boron: 0.001-0.006%, microalloying improvement, refining grains, and strengthening grain boundaries.
Other elements: Vanadium and niobium form carbonitrides, nitrogen refines grains, and carbon content is controlled at 0.07-0.13% to balance strength and weldability.
2) Key characteristics of SA335P92 steel pipe:
High-temperature strength: Creep strength at 600℃/100,000 hours ≥100MPa, 20% higher than P91, allowing for a 15-20% reduction in design wall thickness.
Creep resistance: Maintains creep strength above 480MPa at 650℃, meeting the requirements of ultra-supercritical units.
Thermal fatigue resistance: Low coefficient of thermal expansion (13.5×10⁻⁶/℃) and good thermal conductivity (26-29W/(m·K)), adapting to rapid temperature changes.
Corrosion resistance: Oxidation rate below 0.05mm/year in a steam environment at 600℃; hydrogen-induced cracking sensitivity in sulfur-containing environments is only 1/3 that of conventional materials.
Second, what are the production processes and quality control measures for SA335P92 steel pipes?
1) Smelting Process:
A triple process of electric arc furnace + LF refining + VD vacuum degassing is adopted. Sulfur and phosphorus content ≤0.010%, oxygen content ≤20ppm. Some manufacturers use ESR electroslag remelting to further improve purity.
2) Forming Process:
Piercing Rolling: Continuously cast round billets are heated to 1200-1250℃ in a ring furnace and formed using a Mannesmann skew rolling mill. Compression ratio ≥3:1, eccentricity ≤5%.
Hot Extrusion Technology: Extrusion presses of 3500 tons or more form in a single operation within the 900-1100℃ range. Suitable for thick-walled pipe production, with better microstructure uniformity than the piercing process.
3) Heat Treatment:
Normalizing: 1040-1080℃ (30-50℃ for AC3 and above), holding time 30 minutes for a 25mm thickness. Tempering: 760-780℃ (below AC1 point), hold for at least 4 hours to obtain tempered martensite structure, hardness 180-250HB.
4) Testing Standards: Each batch of products must pass chemical composition analysis, mechanical property testing (tensile strength ≥620MPa, yield strength ≥440MPa, elongation ≥20%), non-destructive testing (100% ultrasonic testing, sensitivity Φ1.6mm flat-bottomed hole), and metallographic inspection (grain size 5-8, non-metallic inclusions ≤1.5).
Third, what are the application areas of SA335P92 steel pipe?
1) Power Industry: Ultra-supercritical boilers: main steam pipelines (566-620℃/25-30MPa), reheat hot section pipelines (typical specification Φ508×80mm). Nuclear Power: In the AP1000 unit’s main feedwater pipeline, improved P92 steel is used in the heat transfer tubes of the fourth-generation high-temperature gas-cooled reactor steam generator, exhibiting superior resistance to radiation embrittlement compared to austenitic stainless steel.
Petrochemicals: Hydrogenation reactor pipelines: Under 550℃/15MPa conditions, a P92 pipeline in a refining project operated continuously for 5 years in sulfur-containing media without exhibiting hydrogen embrittlement.
Ethylene cracking unit quench boiler tubes: Resistant to high-temperature, high-pressure steam impact, with a lifespan three times longer than traditional materials.
2) Other fields: Solar thermal power generation:
In molten salt thermal storage systems, P92 is one of the few metallic materials capable of withstanding molten salt corrosion at 565℃; it has been adopted in 12 projects worldwide with capacities exceeding 50MW.
IGCC combined cycle systems: Resistant to syngas corrosion, extending maintenance cycles from 8000 hours to 20000 hours.
Post time: Jan-16-2026