ASTM A335 Grade P22 (UNS K21590) seamless ferritic alloy steel tubes are engineered for high-temperature and high-pressure service environments. Formulated with nominal 2.25% Chromium and 1% Molybdenum (2-1/4Cr-1Mo), P22 provides high elevated-temperature tensile strength, superior creep-rupture resistance, and scaling resistance at metal temperatures up to 600°C (1112°F).
Supplied in normalized and tempered condition, these tubes serve as critical pressure components in power generation boilers, supercritical steam transport lines, petroleum refinery cracking furnaces, and petrochemical transfer piping.
Technical Specifications
|
Parameter |
Specification Details |
|
Material Standard & Grade |
ASTM A335 / ASME SA335 Grade P22 |
|
Manufacturing Process |
Seamless (Hot Rolled, Pierced, or Cold Drawn) |
|
Size Range (NPS) |
1/2" to 28" (21.3 mm to 711 mm OD) |
|
Wall Thickness (Schedule) |
Sch 40, Sch 80, XS, XXS, Sch 160, heavy-wall up to 100 mm |
|
Standard Lengths |
SRL (5 - 7m), DRL (10 - 12m), or Precision Cut-to-Length |
|
End Preparation |
Plain ends or Beveled ends in accordance with ASME B16.25 |
|
Heat Treatment Condition |
Normalized and Tempered (min. 650°C tempering temperature) |
Chemical Composition (%)
|
Carbon (C) |
0.05 - 0.15 |
|
Manganese (Mn) |
0.30 - 0.60 |
|
Phosphorus (P), max |
0.025 |
|
Sulfur (S), max |
0.025 |
|
Silicon (Si) |
0.50 max |
|
Chromium (Cr) |
1.90 - 2.60 |
|
Molybdenum (Mo) |
0.87 - 1.13 |
Mechanical Properties
• Tensile Strength, min: 415 MPa (60,000 psi)
• Yield Strength, min: 205 MPa (30,000 psi)
• Elongation in 2 in. (50 mm), min: 30% (longitudinal) / 20% (transverse)
• Hardness, max (Brinell): 220 HBW
Manufacturing & Mill Capabilities
Solid round billets are heated in automated rotary hearth furnaces and pierced on mandrel mills, maintaining uniform wall thickness and concentricity even under heavy-wall schedules.
Continuous roller-hearth heat treatment lines with multi-zone computerized pyrometric control guarantee complete microstructural transformation, relieving internal residual stresses and stabilizing grain size.
Multi-roll hydraulic straighteners control camber and ovality within tight ASME tolerances prior to non-destructive testing.
Quality Inspection & Traceability
Compliance with ASTM/ASME standards is verified through rigorous, mandatory testing protocols prior to dispatch:
Non-Destructive Examination (NDE): 100% Ultrasonic Testing (UT) performed per ASTM E213; hydrostatic pressure testing executed at calculated mill test pressures.
Destructive Testing: Tension testing, flattening/bend tests, and Brinell hardness testing conducted at a frequency of one test per heat/lot.
Surface & Dimensional Check: Laser-guided outer diameter, wall thickness, and length verification. Ends are checked for squareness and bevel angle.
Traceability & Certification: Each tube is low-stress stamped and paint-stenciled with heat number, specification, size, and grade. Mill Test Certificates conforming to EN 10204 3.1 are provided standard. Third-Party Inspection (TPI) by agencies such as SGS, TÜV, or Lloyd's Register can be integrated into the inspection hold-points.
Typical Applications
Power Generation: Main steam lines, hot reheat piping, boiler feed pump lines, and superheater headers in fossil-fueled power stations.
Petrochemical & Refining: Hydroprocessing units, catalytic reforming furnaces, high-temperature reactors, and sour-gas transfer piping.
Industrial Processing: High-pressure steam distribution headers operating above 400°C.
Supply Chain & Packaging
Surface Protection:
Coated with clear, weld-compatible anti-rust varnish on exterior surfaces; internal bores kept clean and dry.
End Protection:
Heavy-duty plastic bevel protectors fitted to both ends to prevent transit damage.
Export Bundling:
Bundled securely with high-tensile steel banding, supported by wooden dunnage, or packed in export-grade timber crates upon request.
Lead Times:
Standard sizes maintained for immediate project mobilization; custom rolling schedules managed with typical delivery cycles of 4 - 6 weeks.
Frequently Asked Questions
Q: What is the maximum continuous service temperature for P22 alloy steel?
A: P22 tubes are generally utilized up to 600°C (1112°F). Above this range, creep strength and oxidation resistance degrade rapidly, necessitating higher-alloy grades like P91 (9Cr-1Mo).
Q: Is preheating and post-weld heat treatment (PWHT) required for P22?
A: Yes. Due to the 2.25% chromium content and air-hardening characteristics, preheating (typically 150 - 200°C) during welding and subsequent PWHT are mandatory code requirements to prevent delayed hydrogen cracking.
Q: How does ASTM A335 P22 differ from ASTM A106 Grade B?
A: ASTM A106 Grade B is a carbon steel pipe limited to moderate temperatures (< 400°C). ASTM A335 P22 is a chromium-molybdenum alloy steel engineered specifically to retain mechanical integrity and resist graphitization and creep at elevated temperatures (> 400°C).
Q: Are Mill Test Certificates supplied with the shipment?
A: Yes. Complete physical and chemical MTRs per EN 10204 3.1 accompany every delivery, detailing exact heat analysis, tensile results, hardness values, and NDT verification logs.
Q: Can you supply pre-cut lengths to minimize site fabrication waste?
A: Yes. We offer precision cut-to-length services according to your piping isometric drawings, saving site cutting and beveling time.
Q: What packaging standards are used for ocean freight?
A: Tubes are bundled with heavy-duty steel strapping, fitted with plastic end caps, and wrapped or crated to prevent saltwater corrosion and mechanical impact during international container or break-bulk shipping.
Request a Quote
To facilitate an immediate technical review and commercial proposal, please provide your specific requirements:
Dimensions: Nominal Pipe Size (NPS) and Schedule / Wall Thickness.
Quantity: Total tonnage, linear footage, or piece count.
Delivery Terms: Destination seaport / project location (Incoterms 2020: FOB, CFR, CIF, DDP).
Compliance & Inspection: Standard MTR (3.1) or specific Third-Party Inspection (TPI) requirements.
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