GB 3087——Seamless steel tube for low and medium pressure boilers
GB 3087 standard is applicable to the manufacture of high-quality carbon structural steel hot-rolled (extruded, expanded) and cold drawn (rolled) seamless steel tubes for various structural low-pressure and medium-pressure boilers and locomotive boilers.
WORKING CONDITION
GB 3087 grade 10 seamless steel pipe is mainly used for manufacturing heating surface of industrial boiler, with working pressure ≤ 5.9mpa
When GB 3087 grade 10 is used as heating surface pipe, the maximum wall temperature ≤ 480 ℃, and when GB 3087 grade 10 is used as header and steam pipe, the maximum wall temperature ≤ 430 ℃.
GB3087 STEEL PIPE MECHANICAL PERFORMANCE
| Standard | Grade | Chemical Composition(%) |
| C | Si | Mn | P | S | Cr | Cu | Ni |
| GB3087 | 10 | 0.07～0.13 | 0.17～0.37 | 0.38～0.65 | ≤0.030 | ≤0.030 | 0.3～0.65 | ≤0.25 | ≤0.30 |
mechanical properties:
| Standard | Steel pipe | Wall thickness(mm) | Tensile strength(MPa) | Yield Strength(MPa) | Elongation |
| GB3087 | 10 | / | 335～475 | ≥195 | ≥24 |
ALLOWABLE DEVIATION OF OUTER DIAMETER AND WALL THICKNESS
| Type of steel pipe | Outer diameter(mm) | Tolerance |
| ordinary | advanced |
| Hot rolled tube | OD | ≤159 | ±10%(min±0.50mm) | ±0.75%(min±0.40mm) |
| ＞159 | ±1.0% | ±0.90% |
| WT | ≤20 | ＋15.0%(min＋0.45mm) | ±10%(min±0.30mm) |
| －12.5% －0.35mm) |
| ＞20 | ±12.5% | ±10% |
| OD≥351 | ±15% |
| Cold drawn tube | OD | 10～30 | ±0.40mm | ±0.20mm |
| ＞30～50 | ±0.45mm | ±0.25mm |
| ＞50 | ±1.0% | ±0.75% |
| WT | 1.5～3.0 | 15% | ±10% |
| -10% |
| ＞3.0 | 12.50% | ±10% |
| -10% |
PROCESS PERFORMANCE
(1) Forging and rolling
GB 3087 grade 10 steel has good pressure processability. The initial rolling temperature is 1200-1280 ℃, and the final rolling temperature is 800-850 ℃, which can be cooled by air after rolling (forging).
(2) Cold working
GB 3087 grade 10 steel has excellent plasticity, which can be pulled down, punched, locally upset and expanded in cold state.
(3) Heat treatment
GB 3087 grade 10 seamless steel pipe is generally used in hot rolling state, and cold drawn (rolled) steel pipe is used in heat treatment state. Normalizing heat treatment is often used, and the normalizing temperature is 900-940 ℃.
(4) Welding
The weldability of GB 3087 grade 10 steel is good, and it generally has no hardening tendency. When it is suitable for welding and manufacturing boiler heating surface parts by various welding methods, it usually adopts manual welding or gas shielded welding and other welding methods. E4303 (J422) and e4315 are often used for manual welding. No preheating before welding and no heat treatment after welding.
Test:
- Chemical composition verification test
- hydrostatictest
- Tensile test
- Notched impact test
- Yield strength test
- Ring test
- Nondestructive testing
