ASTM A335 P91 Seamless Steel Pipe
Dimensional Specifications
|
Parameter |
Details |
|
Size Range |
1/2" NB to 24" NB (DN15 to DN600) |
|
Wall Thickness |
SCH 40 to SCH 160 / XXS |
|
Outside Diameter |
Up to 509mm |
|
Wall Thickness |
2.1mm - 20mm (customizable) |
|
Length |
Single Random, Double Random, or Custom Cut |
|
Ends |
Plain End (PE), Beveled End (BE), Threaded |
|
Surface Treatment |
Polished, Varnished, 3LPE, FBE |
Standard:ASTM A335 / ASME SA335
Grade:P91 (UNS K91560)
Type:Seamless - Hot Finished or Cold Drawn
Equivalent Standards:EN 10216-2, ASTM A213, ASME SA213, GOST 550-75
Equivalent Material:T91, X10CrMoVNb9-1, 1.4903
Suitable:Bending, flanging, and fusion welding
Heat Treatment:Supplied in normalized + tempered condition
Technical Parameters
ASTM A335 P91 (also designated ASME SA335 P91, UNS K91560) is a seamless ferritic alloy steel pipe specifically engineered for high-temperature and high-pressure service.
The P91 grade is a 9% chromium - 1% molybdenum alloy with vanadium and niobium micro-additions, providing excellent mechanical properties at elevated temperatures up to 650°C for long-term service. It is the material of choice for ultra-supercritical boilers, high-temperature steam lines, and other critical high-pressure systems where long-term reliability is paramount.
|
Element |
Content Range |
Element |
Content Range |
|---|---|---|---|
|
C |
0.08 - 0.12 |
Cr |
8.00 - 9.50 |
|
Mo |
0.85 - 1.05 |
V |
0.18 - 0.25 |
|
Nb |
0.06 - 0.10 |
N |
0.03 - 0.07 |
|
Si |
0.20 - 0.50 |
Mn |
0.30 - 0.60 |
|
P |
≤ 0.020 |
S |
≤ 0.010 |
|
Performance Index |
Standard Value |
|---|---|
|
Tensile Strength |
≥585 MPa |
|
Yield Strength |
≥415 MPa |
|
Elongation after Fracture |
≥ 20% |
|
Charpy V-notch Impact Energy (-29°C) |
≥18 J (average value) |
Key production processes for smelting and forming:
Electric arc furnace/converter smelting is used, followed by LF refining, VD vacuum degassing, and casting of round billets. In the hot rolling process, the 1200 ℃ steel billet is perforated into capillary tubes, and then formed by continuous rolling. The rolling compression ratio needs to be controlled between 3.5-5.0 to ensure the compactness of the structure.
Heat treatment process:The core process is normalizing+tempering, with a normalizing temperature of 1040±15 ℃ (insulation for 30 minutes/25mm thickness) and a tempering temperature of 770±15 ℃. The cooling rate needs to be precisely controlled to avoid the precipitation of δ ferrite and ensure that the microstructure is tempered martensite with a grain size of ≥ 5.
Welding technical requirements: Preheat to 200-250 ℃ before welding, interlayer temperature ≤ 300 ℃, and local heat treatment at 760±15 ℃ must be carried out after welding. When using ER90S-B9 welding wire, the joint strength coefficient can reach 0.9 or above.
FAQ
Q1: What is the difference between P91 and ordinary carbon steel pipes?
A1: P91 is a high-end heat-resistant alloy steel pipe with special micro-alloying components. It can withstand long-term service at 650°C high temperature and high pressure, with far better creep resistance, oxidation resistance and structural stability than carbon steel pipes. Carbon steel pipes are only suitable for low-temperature and low-pressure conventional fluid transmission, and cannot adapt to extreme thermal industrial environments.
Q2: What is the difference between P91 and P22 alloy pipes?
A2: P91 has higher chromium and molybdenum content and adds vanadium, niobium and nitrogen elements. Its allowable stress at 550°C-600°C is more than 3 times that of P22. P91 is suitable for ultra-supercritical high parameter working conditions, while P22 is only applicable for medium and high temperature conventional thermal systems.
Q3: Can you provide customized size and processing services?
A3: Yes. We support customized outer diameter, wall thickness, fixed-length cutting, surface polishing, anti-rust treatment and pipe end grooving. All customized products strictly comply with ASTM standard tolerance requirements and provide complete inspection reports.
Q4: What quality certificates can you provide?
A4: We can provide factory test certificate (MTC), chemical & mechanical property test report, ultrasonic testing report, hydraulic test report, ASTM/ASME standard certification, and third-party inspection certificates (SGS, BV, TUV) as required by customers.
Q5: What is your production and delivery cycle?
A5: Conventional size products are in stock with 3-7 days fast delivery. Custom non-standard sizes take 15-25 production days. We support bulk order production and provide flexible delivery solutions for global customers.
Q6: What is the service life of P91 seamless pipe?
A6: Under standard installation and normal working conditions (temperature ≤600°C, rated pressure), the service life can reach more than 15-20 years, far longer than ordinary alloy steel pipes, effectively reducing project operation and maintenance costs.
