1. Basic Features Comparison
| Features | P235GH | P265GH |
|---|---|---|
| Strength level | Yield strength ≥235 MPa | Yield strength ≥265 MPa |
| Material positioning | Non-alloy pressure vessel steel (basic grade) | Low alloy fine grain pressure vessel steel ("G" designation) |
| High temperature performance | Design temperature ≤400℃ | Design temperature ≤540℃ (seamless pipe is more common) |
2. Differences in Chemical Composition
| Element | P235GH | P265GH | Influence |
|---|---|---|---|
| C | ≤0.16% | ≤0.20%45 | P265GH is slightly higher, with improved strength |
| Mn | 0.60–1.20% | 0.80–1.40% | Strengthen core elements and improve resilience |
| P/S | P≤0.025%, S≤0.015% | S≤0.010%(More stringent) | Reduce the risk of high temperature embrittlement |
| Alloying elements | No mandatory addition | Contains trace amounts of Cr/Ni (≤0.30%) | Enhanced heat resistance stability |
3. Process and performance differences
| Items | P235GH | P265GH |
|---|---|---|
| Grain Control | No detailed requirements | Adding Nb/V/Ti to refine grains ("G" characteristics) |
| Impact toughness | -20℃ impact energy ≥27J | -20℃ impact energy ≥27J (same requirements) |
| High temperature endurance strength | Yield strength at 400℃≥150 MPa | >150 MPa at 540℃ |
| Manufacturing process | Submerged arc welding/resistance welding (welded pipe standard) | Welded pipes need to be normalized for weld seams |
4. Application Scenario Selection
| Working conditions | Material | Reason |
|---|---|---|
| Medium and low pressure vessels(≤4MPa) | P235GH | Cost optimization to meet basic pressure |
| High temperature equipment(>350℃) | P265GH | Higher high temperature strength retention rate |
| Corrosive environment | Both require an anti-corrosion layer | -- |
| Nuclear power/high pressure vessels | Preferred P265GH seamless pipe | Welded pipes are limited in form (seamless pipes are more reliable) |
