ASTM A213 T91 Alloy Steel Seamless Tube
Nov 05, 2025
The A213 T91 alloy pipe is a seamless steel tube for high-pressure boilers that complies with the ASTM A213/A213M-07a standard. Its chemical composition includes carbon (0.07-0.13%), chromium (8-9.5%), molybdenum (0.85-1.05%), vanadium (0.18-0.25%), niobium (0.06-0.10%), and other elements. After undergoing normalizing and tempering heat treatment, it exhibits excellent high-temperature strength, oxidation resistance, and stable long-term ductility. The material's design stress at 550°C is twice that of conventional T9 steel, and its allowable stress exceeds that of austenitic stainless steel below 620°C. It is suitable for high-temperature superheaters and reheaters in subcritical/supercritical boilers with wall temperatures ≤625°C.
Features:
Oxidation Resistance: Exhibits superior resistance to high-temperature steam corrosion below 620°C compared to austenitic stainless steel, with oxide scale thickness reduced to only 1/3 of T9 steel after long-term service.
Thermal Strength: Delivers a high-temperature specified non-proportional extension strength of 376 MPa at 550°C, with a rupture life exceeding 100,000 hours and tensile strength ≥585 MPa.
Process Stability: Achieved through normalizing and tempering treatment, ensuring consistent tensile strength ≥585 MPa and a high-temperature specified non-proportional extension strength of 376 MPa at 550°C.
Applications:
Power Boilers: Primarily used for main steam pipelines in 600MW+ units, reducing wall thickness by 50% and pipeline system weight by 35% compared to traditional P22 steel, with a 65% reduction in tee usage.
Nuclear Power Equipment: Serves as heat exchanger tubes in the secondary loop of nuclear island systems, withstanding operating conditions of 550°C/20MPa.
Petroleum Cracking Units: Suitable for radiant section furnace tubes in petroleum cracking units, with a service temperature limit of up to 650°C.
Specification
|
Size (Seamless) |
6.35mm o.d to 101.60mm o.d |
|
Standards |
ASTM A213, ASME SA213 |
|
Equivalent Standards |
EN 10216-2, ASTM A213, GOST 550-75, WN 1.4903 |
|
Material |
T91, K91560 |
|
Equivalent Material |
X10CrMoVNb9-1, 1.4903, P91, K91560 |
|
Type |
Seamless |
|
Specialized in |
Large Diameter Size |
|
Wall Thickness |
Schedule 3mm to 15mm. |
|
Length |
max 1~12m |
|
Schedule |
STD, SCH40, SCH80 |
|
Form |
Round, Square, Rectangular, Hydraulic Etc. |
|
Length |
Single Random, Double Random & Cut Length. |
|
Tubing End |
Plain End, Beveled End, Treaded. |
Chemical Compositions of ASTM A213 / ASME SA213 T91 Alloy Steel SMLS Tube:
|
C, % |
Mn, % |
P, % |
S, % |
Si, % |
Cr, % |
Mo, % |
V, % |
N, % |
Ni, % |
Al, % |
Nb, % |
|
0.08-0.12 |
0.3-0.6 |
0.02 max |
0.01 max |
0.2-0.5 |
8.0-9.5 |
0.85-1.05 |
0.18-0.25 |
0.03-0.07 |
0.4 max |
0.04 max |
0.06-0.10 |
Mechanical Properties of ASTM A213 / ASME SA213 T91 Alloy Steel Seamless Tube:
|
Tensile Strength , MPa |
Yield Strength, MPa |
Elongation, % |
Hardness, HB |
|
585 min |
415 min |
20 min |
250 max |
Outside Diameter & Tolerance :
|
Hot rolled |
Outside Diameter, mm |
Tolerance, mm |
|
OD≤101.6 |
+0.4/-0.8 |
|
|
101.6＜OD≤190.5 |
+0.4/-1.2 |
|
|
190.5＜OD≤228.6 |
+0.4/-1.6 |
|
|
Cold Drawn |
Outside Diameter, mm |
Tolerance, mm |
|
OD＜25.4 |
±0.10 |
|
|
25.4≤OD≤38.1 |
±0.15 |
|
|
38.1＜OD＜50.8 |
±0.20 |
|
|
50.8≤OD＜63.5 |
±0.25 |
|
|
63.5≤OD＜76.2 |
±0.30 |
|
|
76.2≤OD≤101.6 |
±0.38 |
|
|
101.6＜OD≤190.5 |
+0.38/-0.64 |
|
|
190.5＜OD≤228.6 |
+0.38/-1.14 |
Wall thickness & Tolerance :
|
Hot rolled |
Outside Diameter, mm |
Tolerance, % |
|
OD≤101.6, WT≤2.4 |
+40/-0 |
|
|
OD≤101.6, 2.4＜WT≤3.8 |
+35/-0 |
|
|
OD≤101.6, 3.8＜WT≤4.6 |
+33/-0 |
|
|
OD≤101.6, WT>4.6 |
+28/-0 |
|
|
OD>101.6, 2.4＜WT≤3.8 |
+35/-0 |
|
|
OD>101.6, 3.8＜WT≤4.6 |
+33/-0 |
|
|
OD>101.6, WT>4.6 |
+28/-0 |
|
|
Cold Drawn |
Outside Diameter, mm |
Tolerance, % |
|
OD≤38.1 |
+20/-0 |
|
|
OD>38.1 |
+22/-0 |
Test and inspection
Packaging and shipping
