USA Piping Solution is amongst the best sellers of ASTM A691 9Cr-1Mo-V (Grade 91) EFW Pipe, offering top-notch alloy steel pipes for different industry requirements. ASTM A691 Grade 91 EFW Pipe is an alloy steel pipe that can withstand high temperatures and high pressures. This pipe is produced through the Electric Fusion Welding Process, whereby pressure vessel quality alloy steel plates are welded with filler metal addition. The production process of this pipe involves heat treatment, radiography, and pressure tests for obtaining mechanical properties and longevity. Due to its alloying elements of chromium, molybdenum, and vanadium, Grade 91 has excellent creep properties and oxidation resistance along with stability in temperature. This steel pipe is extensively used in power generation plants, supercritical boilers, petrochemical industries, and refineries.
ASTM A691 9Cr-1Mo-V (Grade 91) EFW Pipe Specifications Table
| Feature | Details |
|---|---|
| Product Type | LSAW / SAW / EFW (Electric-Fusion-Welded) Pipe |
| Material Grades | 1-1/4CR, 2-1/4CR, 5CR, 9CR, 9, P5, P9, P11, P12, P22, P91 |
| Standard | ASTM A691: Carbon and Alloy Steel Pipe for High-Pressure Service at High Temperatures |
| Class Designation | Class 10, 11, 12, 13, 20, 21, 22, 23, 30, 31, 32, 33, 34, 40, 41, 42, 43, 50, 51, 52, 53, 60, 61, 62, 63, 70, 71, 72, 73... |
| Size (Seamless) | Outer Diameter: 17–914mm (3/8" – 36") |
| Size (LSAW) | Outer Diameter: 457–1422mm (18" – 56") |
| Wall Thickness | 2–60mm (SCH 10, 20, 30, STD, 40, 60, XS, 80, 100, 120, 140, 160, XXS) |
| Technical Methods | Hot-rolled, Cold-drawn, Hot-expanded |
| Surface Treatment | Bare, Black Painting, Varnished, Galvanized, Anti-corrosion (PE, PP, EP, FBE coating) |
| End Finish | Plain end, Beveled (with plastic caps), Square cut, Grooved, Threaded and Coupling |
Chemical Composition of ASTM A691 9Cr-1Mo-V (Grade 91) EFW Pipe
| Element | 1 CR | 1-1/4 CR | 2-1/4 CR | 5 CR | 9 CR | 91 |
|---|---|---|---|---|---|---|
| Carbon (C) | 0.05–0.17 | 0.05–0.17 | 0.05–0.15 | 0.15 max | 0.15 max | 0.08–0.12 |
| Manganese (Mn) | 0.40–0.65 | 0.40–0.65 | 0.30–0.60 | 0.30–0.60 | 0.30–0.60 | 0.30–0.60 |
| Phosphorus (P) | 0.025 max | 0.025 max | 0.025 max | 0.025 max | 0.025 max | 0.020 max |
| Sulfur (S) | 0.025 max | 0.025 max | 0.025 max | 0.025 max | 0.025 max | 0.010 max |
| Silicon (Si) | 0.15–0.40 | 0.50–0.80 | 0.50 max | 0.50 max | 1.00 max | 0.20–0.50 |
| Chromium (Cr) | 0.80–1.15 | 1.00–1.50 | 2.00–2.50 | 4.00–6.00 | 8.00–10.0 | 8.00–9.50 |
| Molybdenum (Mo) | 0.45–0.60 | 0.45–0.65 | 0.90–1.10 | 0.45–0.65 | 0.90–1.10 | 0.85–1.05 |
| Vanadium (V) | — | — | — | — | 0.04 max | 0.18–0.25 |
ASTM A691 9Cr-1Mo-V (Grade 91) EFW Pipe Mechanical Properties
| Property | Metric Value | Imperial Value |
|---|---|---|
| Yield Strength | ≥ 415MPa | ≥ 60ksi |
| Ultimate Tensile Strength (UTS) | ≥ 585MPa | ≥ 85ksi |
| Elongation | ≥ 20 | — |
| Hardness | ≤ 248HB | — |
Comparison Table of Grade vs Grade 9 (9Cr-1Mo, no V)
| Property | This Grade | Grade 9 (9Cr-1Mo, no V) | Key Difference |
|---|---|---|---|
| Vanadium content | 0.18–0.25 | None | V is the key differentiator |
| Creep rupture strength | Higher (+30 vs Gr9) | Lower | Gr91 preferred above 550°C |
| Max service temp | ~625°C | ~600°C | 25°C advantage — significant in power gen |
| PWHT requirement | Mandatory — 760°C min | Mandatory — 730°C | Both require PWHT — Grade 91 stricter |
| Industry status | Industry standard for ultra-high temp | Legacy grade, being replaced | Grade 91 is the current spec of choice |
| Weld complexity | High — V makes HAZ harder | Moderate | Grade 91 needs more qualified welders |
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Heat Treatment Chart of ASTM A691 9Cr-1Mo-V (Grade 91) EFW Pipe
| Pipe Grade | ASTM Spec | PWHT (Stress Relieving) Range °F (°C) | Normalizing Temp. Max °F (°C) | Quenching Temp. Max °F (°C) | Tempering Temp. Min °F (°C) |
|---|---|---|---|---|---|
| CM-65 | A 204 | 1100–1200 (590–650) | 1700 (925) | — | — |
| CM-70 | A 204 | 1100–1200 (590–650) | 1700 (925) | — | — |
| CM-75 | A 204 | 1100–1200 (590–650) | 1700 (925) | — | — |
| CMSH-70 | A 537 | 1100–1200 (590–650) | 1700 (925) | — | — |
| CMS-75 | A 299 | 1100–1200 (590–650) | 1700 (925) | — | — |
| CMSH-80 | A 537 | 1100–1200 (590–650) | Note A | 1700 (925) | 1100–1250 (590–675) |
| 1/2 CR | A 387 | 1100–1300 (590–705) | 1850 (1010) | 1700 (925) | 1150–1375 (620–745) |
| 1 CR | A 387 | 1100–1350 (590–730) | 1850 (1010) | 1700 (925) | 1150–1375 (620–745) |
| 1 1/4 CR | A 387 | 1100–1375 (590–745) | 1850 (1010) | 1700 (925) | 1150–1375 (620–745) |
| 2 1/4 CR | A 387 | 1200–1400 (650–760) | 1850 (1010) | 1700 (925) | 1250–1400 (675–760) |
| 3 CR | A 387 | 1200–1400 (650–760) | 1850 (1010) | 1700 (925) | 1250–1400 (675–760) |
| 5 CR | A 387 | 1200–1400 (650–760) | 1850 (1010) | 1650 (900) | 1300–1400 (705–760) |
| 9 CR | A 387 | 1325–1375 (715–745) | Note B | — | 1325–1375 (715–745) |
| 91 | A 387 | 1350–1420 (730–770) | 1900–2000 (1040–1095) | 1900 min (1040 min) | 1350–1440 (730–780) |
Different Classes Range of ASTM A691 9Cr-1Mo-V (Grade 91) EFW Pipe
| Class | Heat Treatment on Pipe | Radiography (RT) | Pressure Test |
|---|---|---|---|
| Class 10 | None | None | None |
| Class 11 | None | Section 9 | None |
| Class 12 | None | Section 9 | Section 8.3 |
| Class 13 | None | None | Section 8.3 |
| Class 20 | Stress Relieved | None | None |
| Class 21 | Stress Relieved | Section 9 | None |
| Class 22 | Stress Relieved | Section 9 | Section 8.3 |
| Class 23 | Stress Relieved | None | Section 8.3 |
| Class 30 | Normalized | None | None |
| Class 31 | Normalized | Section 9 | None |
| Class 32 | Normalized | Section 9 | Section 8.3 |
| Class 33 | Normalized | None | Section 8.3 |
| Class 40 | Normalized and Tempered | None | None |
| Class 41 | Normalized and Tempered | Section 9 | None |
| Class 42 | Normalized and Tempered | Section 9 | Section 8.3 |
| Class 43 | Normalized and Tempered | None | Section 8.3 |
Application Uses of ASTM A691 9Cr-1Mo-V (Grade 91) EFW Pipe
Our Alloy Steel A691 9 Cr Welded Pipes are used in a wide range of applications and various industries. Below are a few of them:
- Petrochemical Industry
- Oil and Gas Industry
- Chemical Industry
- Power Plant Industry
- Energy Industry
- Pharmaceuticals Industry
- Pulp & Paper Indusry
- Food Processing Industry
- Aerospace Industry
- Refining Industry
Other Standars of ASTM A691
| Tier | Anchor Text (Linked) | Usage / Application Area |
|---|---|---|
| TIER 1 | ASTM A691 EFW Alloy Steel Pipe | Used as a parent standard in high-pressure piping systems for power plants, refineries, petrochemical units, and boiler applications. |
| TIER 1 | Chrome Moly Pipes & Tubes | Used in high-temperature and high-pressure industrial environments such as oil & gas processing, thermal power plants, and refinery operations. |
| TIER 2 | ASTM A691 Grade 9 (9Cr-1Mo) EFW Pipe | Used in superheater tubes, boilers, and high-temperature steam lines in power generation and refinery industries. |
| TIER 2 | ASTM A691 Grade 22 (2¼Cr-1Mo) EFW Pipe | Used in high-pressure boiler systems, petrochemical plants, and refinery equipment requiring superior creep resistance. |
| TIER 2 | Alloy Steel Welded Pipes & Tubes | Used in structural fabrication, industrial piping systems, and moderate-pressure fluid transport applications. |
| TIER 2 | ASTM A335 P91 Alloy Steel Pipe | Used in ultra-supercritical boilers, power generation plants, and high-temperature steam piping systems. |
Frequently Asked Questions
What is ASTM A691 Grade 91 pipe?
It is a high-strength chromium-molybdenum-vanadium alloy steel pipe made by the EFW process for high-temperature and high-pressure service.
What is 9Cr-1Mo-V material?
It is an alloy steel containing about 9 chromium, 1 molybdenum, and vanadium, known for excellent creep strength and heat resistance.
What is ASTM A691 used for?
It is used in power plants, boilers, refineries, and petrochemical industries for high-pressure and high-temperature piping systems.
Is ASTM A691 Grade 91 suitable for high temperature applications?
Yes, it is designed for long-term service in very high-temperature environments.
Is ASTM A691 Grade 91 better than Grade 11 or Grade 22?
Yes, Grade 91 offers higher strength and better creep resistance, making it suitable for more severe operating conditions.
