| Ship Duilding Tube | 
| GB/T5312-1999(Hot rolling, extrusion, pipe expansion) | 
| Ship Duilding Tube |  |  |  |  |  |  |  |  |  |  | 
| Size tolerance |  |  |  |  |  |  |  |  |  |  | 
| Outer diameter(D) | ≤159 | >159 |  |  |  |  |  |  |  |  |  |  | 
| Allowable deviation of outer diameter | ±1.0%(Mini±0.5mm) | ±1.25% |  |  |  |  |  |  |  |  |  |  | 
| wt(S) | ≤20 | S>20 | D≥351 |  |  |  |  |  |  |  |  |  |  | 
| Allowable deviation of outer diameter | +15%,-10%(mini+0.45mm,-0.30mm) | ±10% | ±15% |  |  |  |  |  |  |  |  |  |  | 
| Longitudinal mechanical properties of Ship Duilding Tube |  |  |  |  |  |  |  |  |  | 
| Category | Grade | Tensile strength(MPa) | Yield point(MPa)≥ | Elongation(%)≥ |  |  |  |  |  |  |  |  |  | 
| Carbon steel and carbon-manganese steel | 360 | 360-480 | 215 | 24 |  |  |  |  |  |  |  |  |  | 
| 410 | 410-530 | 235 | 22 |  |  |  |  |  |  |  |  |  | 
| 490 | 490-610 | 285 | 21 |  |  |  |  |  |  |  |  |  | 
| 1Cr0.5Mo | 440 | 440-600 | 275 | 22 |  |  |  |  |  |  |  |  |  | 
| 2.25Cr1Mo | 410 | 410-560 | 235 | 20 |  |  |  |  |  |  |  |  |  | 
| 490 | 490-640 | 275 | 16 |  |  |  |  |  |  |  |  |  | 
| Chemical composition of marine pipe | 
| Classification of marine pipes | Grade | C | Si | Mn | P≤ | S≤ | Cr | Mo | Ni | Cu | Sn | W | 总量 | 
| Carbon steel and carbon-manganese steel | 360 | ≤0.17 | ≤0.35 | 0.40-0.80 | 0.04 | 0.04 | ≤0.25 | ≤0.10 | ≤0.30 | ≤0.30 | - | - | ≤0.70 | 
| 410 | ≤0.21 | ≤0.35 | 0.40-1.20 | 0.04 | 0.04 | ≤0.25 | ≤0.10 | ≤0.30 | ≤0.30 | - | - | ≤0.70 | 
| 440 | ≤0.23 | ≤0.35 | 0.80-1.50 | 0.04 | 0.04 | ≤0.25 | ≤0.10 | ≤0.30 | ≤0.30 | - | - | ≤0.70 | 
| 1Cr0.5Mo | 440 | 0.10-0.18 | 0.10-0.35 | 0.40-0.70 | 0.04 | 0.04 | 0.70-1.10 | 0.45-0.65 | ≤0.30 | ≤0.25 | ≤0.03 | ≤0.020 | - | 
| 2.25Cr1Mo | 410 | 0.08-0.15 | 0.10-0.35 | 0.40-0.70 | 0.04 | 0.04 | 2.00-2.50 | 0.90-1.20 | ≤0.30 | ≤0.25 | ≤0.03 | ≤0.020 | - | 
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