P235GH Carbon Steel Boiler Steel Pipe
P235GH is a non-alloy quality steel grade specifically designed for pressure and elevated temperature applications, most commonly in the manufacture of boilers and pressure vessels. The "P" stands for "Pressure," and "GH" indicates suitability for elevated temperatures (G for gases, H for high temperature).
This material is defined under the European standard EN 10216-2: Seamless steel tubes for pressure purposes - Technical delivery conditions - Part 2: Non-alloy and alloy steel tubes with specified elevated temperature properties.
Key Characteristics:
Application: Primarily used for critical components in steam boilers, superheaters, heat exchangers, and pressure piping systems where high pressure and temperature resistance are required.
Temperature Service: Suitable for long-term service at elevated temperatures, typically up to approximately 450°C - 500°C.
Weldability: Exhibits good weldability using common methods (SMAW, GTAW, SAW, etc.), though preheating and post-weld heat treatment (PWHT) may be required depending on thickness and application codes.
Formability: Good formability and machinability in normalized or similar heat-treated condition.
Corrosion Resistance: Offers standard carbon steel corrosion resistance. For aggressive environments, additional protection (coatings) or material upgrade (alloy steel) is necessary.
Typical Chemical Composition (Weight %)
| Element | Minimum | Maximum |
|---|---|---|
| Carbon (C) | - | 0.16 |
| Silicon (Si) | 0.10 | 0.35 |
| Manganese (Mn) | 0.40 | 1.20 |
| Phosphorus (P) | - | 0.025 |
| Sulfur (S) | - | 0.015 |
| Aluminum (Al) total | 0.020 min | - |
*Note: The composition may vary slightly depending on the product form and specific manufacturer's internal standards, but it always conforms to EN 10216-2.*
Typical Mechanical Properties
Based on normalized condition for seamless tubes.
| Property | Value | Remarks |
|---|---|---|
| Yield Strength (Rp0.2) | ≥ 235 MPa (min) | The "235" in the grade name indicates the min yield strength in MPa. |
| Tensile Strength (Rm) | 360 - 510 MPa | |
| Elongation (A) | ≥ 25% (min, on 5.65√So) | Indicates good ductility. |
| Impact Toughness | Specified at room temperature | Typically tested. Minimum average energy often required (e.g., 27 J at 20°C). |
| Test Temperature | Room Temperature (as delivered) |
Common Specifications and Equivalent Grades
| Standard | Grade | Similar/Equivalent Grades (Approximate) |
|---|---|---|
| EN 10216-2 | P235GH | Primary European standard. |
| ISO 9327-2 | P235GH | International equivalent. |
| DIN 17175 | 17Mn4 | Older German standard, very close. |
| ASTM/AISI | - | No direct equivalent. Similar to some ASTM A-516 Gr. 60/65 or A-106 B/C in some applications, but not identical due to temperature-specific properties. |
| GB (China) | 20G | Chinese boiler steel, often considered a general counterpart. |
Typical Delivery Conditions & Manufacturing
Process: Primarily manufactured as seamless pipes/tubes through hot extrusion or piercing processes.
Heat Treatment: Usually supplied in the normalized (+N) condition to achieve the specified microstructure and mechanical properties.
Testing: Subject to rigorous non-destructive testing (NDT) such as ultrasonic testing, hydrostatic testing, and eddy current testing as per order requirements and standard.
Summary Table: P235GH Boiler Steel Pipe at a Glance
| Feature | Description |
|---|---|
| Standard | EN 10216-2 |
| Primary Use | Boiler tubes, pressure vessels, superheater coils, high-temperature/pressure piping. |
| Key Strength | Minimum Yield Strength of 235 MPa with guaranteed properties at elevated temperatures. |
| Main Advantage | Reliable and cost-effective material for medium-temperature pressure applications with good weldability. |
| Limitation | Not suitable for very high temperatures (>500°C) or highly corrosive environments without protection. |
Disclaimer: The information provided is for general reference. For critical applications, always consult the official material standard (EN 10216-2), the material certificate from the supplier, and the relevant design codes (e.g., ASME, PED).
