ASTM A691 1-1/4Cr-1/2Mo (Grade 11) EFW Pipe represents an alloy steel pipe designed specifically for use at high temperatures and pressures. With the Electric Fusion Welding (EFW) process, such pipes guarantee a perfect uniformity in welding, mechanical strength, and longevity of the product under tough conditions. In addition, ASTM A691 Grade 11 pipe is mainly made of Chromium, Molybdenum, Carbon, and Manganese to increase resistance to oxidation and creep, and also to provide thermal stability. The tensile strength may be as high as 415 – 585 MPa, and the yield strength is 205 to 415 MPa. This pipe is highly resistant to demanding conditions and finds application in various equipment such as boilers, heat exchangers, refineries, petrochemical facilities, and power generation. USA Piping Solution delivers high-quality ASTM A691 Grade 11 EFW pipes in different sizes and specifications.
Specifications of ASTM A691 1-1/4Cr-1/2Mo (Grade 11) EFW Pipe
| Feature | Technical Details |
|---|---|
| Product Type | LSAW, SAW, and EFW (Electric Fusion Welded) Pipe |
| Material Grades | 1-1/4CR, 2-1/4CR, 5CR, 9CR, 91 (Equivalent to P5, P9, P11, P12, P22, P91) |
| Standard Spec | ASTM A691: Carbon and Alloy Steel Pipe for High-Pressure Service |
| Class Designations | Classes 10 through 73 (covers heat treatment and radiography levels) |
| Size Range (OD) | Seamless: 3/8" – 36" (17–914mm) LSAW: 18" – 56" (457–1422mm) |
| Wall Thickness | 2mm – 60mm (All Schedules: SCH 10 to XXS) |
| Length | Single/Double Random; 5m–14m (standard 6m and 12m options) |
| End Finishes | Plain, Beveled, Grooved, Threaded & Coupled |
| Surface Finish | Bare, Black Paint, Galvanized, Anti-corrosion (PE, PP, FBE coating) |
| Technical Methods | Hot-rolled, Cold-drawn, Hot-expanded |
| Inspection & Testing | Eddy Current, Hydrostatic, Ultrasonic (UT), NDT, Chemical/Physical analysis |
Chemical Composition of ASTM A691 1-1/4Cr-1/2Mo (Grade 11) EFW Pipe
| Element | Composition (%) |
|---|---|
| Carbon (C) | 0.05 - 0.15 |
| Manganese (Mn) | 0.30 - 0.60 |
| Phosphorus (P) | ≤ 0.025 |
| Sulfur (S) | ≤ 0.025 |
| Silicon (Si) | 0.50 - 1.00 |
| Chromium (Cr) | 1.00 - 1.50 |
| Molybdenum (Mo) | 0.44 - 0.65 |
Mechanical Properties of ASTM A691 1-1/4Cr-1/2Mo (Grade 11) EFW Pipe
| Property | Value |
|---|---|
| Tensile Strength | 415 MPa (Min) |
| Yield Strength | 205 MPa (Min) |
| Elongation | 20 (Min) |
| Hardness | As per ASTM Standard |
Comparison Table Between Grade vs Grade 22 (2¼Cr-1Mo)
| Property | This Grade | Grade 22 (2¼Cr-1Mo) | Key Difference |
|---|---|---|---|
| Cr content | 1.00–1.50 | 2.00–2.50 | Grade 22 more Cr = better high-temp oxidation resistance |
| Mo content | 0.44–0.65 | 0.87–1.13 | Grade 22 more Mo = better creep resistance |
| Max service temp | ~510°C | ~550°C | Grade 22 for higher temp service |
| Cost | Lower | Higher | Grade 11 cost advantage for lower-temp service |
| PWHT temp | 675–760°C | 675–760°C | Same range |
| Typical use | LP/IP steam lines, lower-temp process | HP steam, high-temp process | Different service windows — not interchangeable |
Tensile Strength of ASTM A691: Standard vs. Class 2 Plates
| Grade | Plate Class | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (50mm) | Reduction of Area* |
|---|---|---|---|---|---|
| 1CR | Standard | 380 - 550 | 230 min | 22 min | — |
| 1CR | Class 2 | 450 - 585 | 275 min | 22 min | — |
| 1-1/4CR | Standard | 415 - 585 | 240 min | 22 min | — |
| 1-1/4CR | Class 2 | 515 - 690 | 310 min | 22 min | — |
| 2-1/4CR, 5CR, 9CR | Standard | 415 - 585 | 205 min | 18 min | 40 min |
| 2-1/4CR, 5CR, 9CR | Class 2 | 515 - 690 | 310 min | 18 min | 40 min |
| 91 | Standard | 415 - 585 | 205 min | 18 min | 40 min |
| 91 | Class 2 | 585 - 760 | 415 min | 18 min | — |
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ASTM A691 1-1/4Cr-1/2Mo (Grade 11) EFW Pipe Heat Treatment Chart
| Pipe Grade | ASTM Specification | Post-Weld Heat-Treat (PWHT) Range °F (°C) | Normalizing Temp. Max °F (°C) | Quenching Temp. Max °F (°C) | Tempering Temp. Min °F (°C) |
|---|---|---|---|---|---|
| CM-65 | A 204/A 204M | 1100 - 1200 (590 - 650) | 1700 (925) | — | — |
| CM-70 | A 204/A 204M | 1100 - 1200 (590 - 650) | 1700 (925) | — | — |
| CM-75 | A 204/A 204M | 1100 - 1200 (590 - 650) | 1700 (925) | — | — |
| CMSH-70 | A 537/A 537M | 1100 - 1200 (590 - 650) | 1700 (925) | — | — |
| CMS-75 | A 299/A 299M | 1100 - 1200 (590 - 650) | 1700 (925) | — | — |
| CMSH-80 | A 537/A 537M | 1100 - 1200 (590 - 650) | A | 1700 (925) | 1100 - 1250 (590 - 675) |
| 1/2CR | A 387/A 387M | 1100 - 1300 (590 - 705) | 1850 (1010) | 1700 (925) | 1150 - 1375 (620 - 745) |
| 1CR | A 387/A 387M | 1100 - 1350 (590 - 730) | 1850 (1010) | 1700 (925) | 1150 - 1375 (620 - 745) |
| 1 1/4CR | A 387/A 387M | 1100 - 1375 (590 - 745) | 1850 (1010) | 1700 (925) | 1150 - 1375 (620 - 745) |
| 2 1/4CR | A 387/A 387M | 1200 - 1400 (650 - 760) | 1850 (1010) | 1700 (925) | 1250 - 1400 (675 - 760) |
| 3CR | A 387/A 387M | 1200 - 1400 (650 - 760) | 1850 (1010) | 1700 (925) | 1250 - 1400 (675 - 760) |
| 5CR | A 387/A 387M | 1200 - 1400 (650 - 760) | 1850 (1010) | 1650 (900) | 1300 - 1400 (705 - 760) |
| 9CR | A 387/A 387M | 1325 - 1375 (715 - 745) | B | — | 1325 - 1375 (715 - 745) |
| 91 | A 387/A 387M | 1350 - 1420 (730 - 770) | 1900 - 2000 (1040 - 1095) | 1900 min (1040 min) | 1350 - 1440 (730 - 780) |
Application Uses of ASTM A691 1-1/4Cr-1/2Mo (Grade 11) EFW Pipe
- Power Generation Industry
- Oil & Gas Industry
- Petrochemical Industry
- Chemical Processing Industry
- Refinery Industry
- Fertilizer Industry
- Heat Exchanger Manufacturing Industry
- Boiler Manufacturing Industry
- Thermal Energy Industry
Other Grades
| Serial No. | Standard Name (Anchor Text + Link) | Application Uses |
|---|---|---|
| 1 | ASTM A691 EFW Alloy Steel Pipe | Used in power plants, boilers, heat exchangers, and petrochemical pressure systems requiring welded high-temperature service. |
| 2 | Chrome Moly Pipes & Tubes | Applied in high-temperature and high-pressure industrial systems such as refineries, oil & gas plants, and thermal power units. |
| 3 | ASTM A691 Grade 22 (2¼Cr-1Mo) EFW Pipe | Used in superheater tubes, boilers, and refinery services requiring excellent creep strength and oxidation resistance. |
| 4 | ASTM A335 P11 Alloy Steel Pipe | Widely used in refineries, petrochemical plants, and high-pressure steam lines in power generation industries. |
| 5 | Alloy Steel Welded Pipes & Tubes | Used in structural applications, fabrication units, and moderate-pressure industrial piping systems. |
| 6 | Alloy Steel Pipes & Tubes | Applied in general engineering, construction, oil & gas, and industrial fluid transportation systems. |
Frequently Asked Questions
What is ASTM A691 Grade 11 pipe?
It is a chromium-molybdenum alloy steel pipe made using the EFW process for high-temperature and high-pressure service.
What is 1-1/4Cr-1/2Mo material?
It is a low-alloy steel containing about 1.25 chromium and 0.5 molybdenum, known for strength and heat resistance.
What is the difference between ASTM A691 Grade 11 and Grade 22?
Grade 22 has higher chromium and molybdenum content, giving it better creep strength and higher temperature resistance than Grade 11.
What is ASTM A691 used for?
It is used in boilers, power plants, refineries, petrochemical plants, and other high-pressure piping systems.
Is ASTM A691 Grade 11 suitable for high temperature applications?
Yes, it is designed for elevated temperature and pressure service with good heat and oxidation resistance.
