ASTM A335 has a grade P23 Pipes, also called UNS K40712, are a highly advanced type of chrome-moly alloy steel pipe designed to perform reliably in a high-temperature environment. The grade is made using modified 2.25 percent chromium steel and is enriched with other elements such as tungsten, molybdenum, vanadium, niobium and small quantities of boron. These additions together with controlled heat treatment assist in the creation of a refined microstructure which can provide enhanced creep strength and enable the pipe to operate at higher operating temperatures than traditional pipes. The seamless design provides high structural integrity which makes such pipes suitable in boilers, pressure system and supercritical applications. At USA Piping Solution, we also supply a wide range of related grades of alloy steel Pipes to various high pressure and temperature applications.
Specifications ASTM A335 P23 Alloy Steel Seamless Pipe
| Feature | Specification Details |
|---|---|
| Trade Names | Chrome Moly P23, 2.25Cr-1.6W-V-Nb Pipe, Ferritic Alloy Steel |
| UNS Designation | K40712 |
| Standards | ASTM A335, ASME SA335 |
| Type | Seamless (Standard & Large Diameter) |
| Nominal Size (NB) | 1/8" NB to 24" NB |
| Outer Dimensions | 19.05 mm - 114.3 mm |
| Wall Thickness (WT) | 2.0 mm - 14 mm |
| Schedule Range | SCH 20 to SCH XXS (Up to 250 mm thickness on request) |
| Length | Max 16,000 mm (Single/Double Random & Cut Length) |
| Forms Available | Round, Square, Rectangular, Hydraulic, etc. |
| End Connections | Plain End, Beveled End, Threaded |
Chemical Composition of ASTM A335 P23 Alloy Steel Seamless Pipes
| Element | C | Mn | P | S | Si | Cr | Mo |
|---|---|---|---|---|---|---|---|
| Content | 0.04-0.10 | 0.10-0.60 | 0.03 max | 0.01 max | 0.50 max | 1.90-2.60 | 0.05-0.30 |
ASTM A335 P23 Pipe Mechanical Properties
| Property | Tensile Strength | Yield Strength | Elongation |
|---|---|---|---|
| Value | 510 MPa min | 400 MPa min | 20% min |
Equivalent Grade of ASTM A335 P23 Pipe
| DIN | EN | BS | SNF | ASTM | ASME |
|---|---|---|---|---|---|
| - | EN 7CrWMoNb9-6 | - | - | ASTM A335 Grade P23 | ASME SA 335 Grade P23 |
ASTM A213 Alloy Steel P23 Tubes Outside Diameter & Tolerances
| Manufacturing Process | Outside Diameter (mm) | Tolerance (mm) |
|---|---|---|
| Hot Rolled | OD <= 101.6 | +0.4 / -0.8 |
| Hot Rolled | 101.6 < OD <= 190.5 | +0.4 / -1.2 |
| Hot Rolled | 190.5 < OD <= 228.6 | +0.4 / -1.6 |
| Cold Drawn | OD < 25.4 | +/-0.10 |
| Cold Drawn | 25.4 <= OD <= 38.1 | +/-0.15 |
| Cold Drawn | 38.1 < OD < 50.8 | +/-0.20 |
| Cold Drawn | 50.8 <= OD < 63.5 | +/-0.25 |
| Cold Drawn | 63.5 <= OD < 76.2 | +/-0.30 |
| Cold Drawn | 76.2 <= OD <= 101.6 | +/-0.38 |
| Cold Drawn | 101.6 < OD <= 190.5 | +0.38 / -0.64 |
| Cold Drawn | 190.5 < OD <= 228.6 | +0.38 / -1.14 |
Wall Thickness and Tolerance Chart of ASTM A213 P23 Tubes
| Manufacturing Process | Condition (OD & WT) | Tolerance (%) |
|---|---|---|
| Hot Rolled | OD <= 101.6, WT <= 2.4 | +40 / -0 |
| Hot Rolled | OD <= 101.6, 2.4 < WT <= 3.8 | +35 / -0 |
| Hot Rolled | OD <= 101.6, 3.8 < WT <= 4.6 | +33 / -0 |
| Hot Rolled | OD <= 101.6, WT > 4.6 | +28 / -0 |
| Hot Rolled | OD > 101.6, 2.4 < WT <= 3.8 | +35 / -0 |
| Hot Rolled | OD > 101.6, 3.8 < WT <= 4.6 | +33 / -0 |
| Hot Rolled | OD > 101.6, WT > 4.6 | +28 / -0 |
| Cold Drawn | OD <= 38.1 | +20 / -0 |
| Cold Drawn | OD > 38.1 | +22 / -0 |
P22 vs P23 Pipe Comparison Table
| Parameter | ASTM A335 P22 Pipe | ASTM A335 P23 Pipe |
|---|---|---|
| Nominal Composition | 2.25Cr - 1Mo | 2.25Cr - W, V, Nb, B (Modified) |
| Chromium Content | 2.0 - 2.5% | 1.9 - 2.6% |
| Molybdenum Content | 0.87 - 1.13% | 0.05 - 0.30% |
| Tungsten (W) | Not Present | 1.45 - 1.75% |
| Microalloying Elements | None | V, Nb, B present |
| Creep Strength | Good | Superior (higher long-term strength) |
| Maximum Service Temperature | Up to ~600 deg C | Up to ~620-650 deg C |
| Oxidation Resistance | Good | Improved at elevated temperatures |
| Mechanical Strength | High | Higher (especially at high temp) |
| Heat Treatment | Normalized & Tempered | Precisely Controlled Normalized & Tempered |
| Wall Thickness Requirement | Standard thickness | Allows thinner wall design |
| Weldability | Good | Moderate (requires controlled procedures) |
| Cost Level | Moderate | Higher |
| Typical Applications | Boilers, pressure vessels, steam lines | Supercritical boilers, headers, high-temp piping |
| When to Select | Standard high-temp applications | When higher efficiency, creep resistance & longer life are required |
Applications & Industries of ASTM A335 P23 Pipes
- Power generation plants (thermal & supercritical units)
- Oil & gas refineries
- Petrochemical industries
- Chemical processing plants
- Energy and utility sectors
- EPC (Engineering, Procurement & Construction) projects
- Heavy industrial manufacturing
Heat Treatment of ASTM A335 P23 Pipes
Proper heat treatment is one of the key factors of the successful performance of ASTM A335 P23 pipes. In order to reach the needed strength and durability, material is subjected to controlled thermal processing:
Normalizing (Austenitizing): The pipes are heated evenly to around 1040°C to 1080°C (1900°F to 1975°F). This operation assists in the solution of the carbides and a uniform interior structure is guaranteed. The material is heated and then cooled in air or by some accelerated cooling method such as quenching.
Tempering: Once normalised the pipes are reheated once again to a range of about 730°C to 800°C (1350°F to 1470°F). This is a step to tighten the microstructure into a stable bainitic or martensitic form, which enhances creep strength, toughness, and long-term performance at high temperatures.
Related Alloy Steel Pipe Grades
- ASTM A335 P91 Pipes
- ASTM A335 P9 Pipes
- ASTM A335 P22 Pipes
- ASTM A335 P11 Pipes
- ASTM A335 P5 Pipes
- Boiler Tubes and Pipes
- Alloy Steel Pipes and Tubes
- ASTM A213 T92 Tubes
- ASTM A213 T12 Tubes
Frequently Asked Questions
What is P23 material?
P23 is a low-alloy chromium-molybdenum steel (2.25Cr) enhanced with tungsten, vanadium, niobium, and boron for better strength and high-temperature performance.
What is ASTM A335 material?
ASTM A335 is a standard specification for seamless ferritic alloy steel pipes used in high-temperature and high-pressure applications.
What is the UNS number for ASTM A335 P23?
The UNS number for ASTM A335 P23 is K40712.
What are the mechanical properties of P23 pipe?
P23 pipe has a minimum tensile strength of 510 MPa, yield strength of 400 MPa, and elongation of 20%.
What is the maximum temperature for P23 pipe?
P23 pipe can typically be used at temperatures up to 620-650 deg C, depending on service conditions.