GB/T8162 Seamless Carbon Steel Pipe As Seamless Steel Tubes and Seamless Carbon Steel Tube, its main purpose is For Structure Purposes. As Hydraulic Cylinder Steel TubeUnder normal circumstances, its main material is 10# 20# 25# 35# 45# 20Mn 25Mn.1 the hot rolled steel pipe should be delivered in hot rolling or heat treatment state, and require the heat treatment state to be indicated in the contract when the heat treatment state is delivered. 2 the cold drawn steel pipe should be delivered in heat treatment. In accordance with the buyer's request, the two parties shall negotiate and indicate in the contract that they can also be delivered in a cold drawn state.
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Steel Grade/Steel Material:10# 20# 25# 35# 45# 20Mn 25Mn
Steel pipe standard:GB/T8162
Characteristic:
Good concentricity
Good OD and ID tolerance
High Precision
Stable quality
Smooth Roughness
TORICH QUALITY ASSURANCE
Production Processs:
RAW MATERIAL
↓
INCOMING INSPECTION
↓
STORAGE → CUTTING→HAMMERING → PICKING LUBRICATION → CLEANING → PHOSPHORI CLEAN
↓
ENDS CUTTING←STRAIGHTENING←HEAT TREATMENT↔MIDDLLE CHECK↔ COLD DRAWING ← LUBRICATING
↓
FINAL INSPECTION→BUNDING→STORAGE
Heat Treatment: Hot Rolling & Cold Drawn
Tolerance of the OD &WT:
OD Tolerance:
| Production Method | OD Tolerance |
| Hot Rolling(Extrusion) | ±1% or ±0.50mm |
| Cold Drawn(Cold Rolled) | ±1% or ±0.30mm |
Tolerance for wall thickness:
1.Wall thickness tolerance of Hot Rolling steel tube:
| Production Method | OD (DN) | WT/OD | Tolerance |
| Extruded tube | ≤102 | / | ±12.5% or ±0.40mm |
| ＞102 | ≤0.05 | ±15% or ±0.40mm |
| ＞0.05-0.10 | ±12.5% or ±0.40mm |
| ＞0.10 | +12.5% -10% |
| Heat expanding steel tube | / | ±15% |
2.Wall thickness tolerance of Cold Drawn(Cold Rolled) steel tube:
| Production Method | WT | Tolerance |
| Cold Drawn(Cold Rolled) steel tube | ≤3 | +15%/-10% or ±0.40mm |
| ＞3 | +12.5% -10% |
Bending tolerance:
WT≤15mm, Bending≤1.5mm/m
WT＞15mm~30mm, Bending≤2.0mm/m
WT＞30mm/OD≥351mm, Bending≤3.0mm/m
Ovality and Wall unevenness:
The ovality and wall unevenness should be no more than 80% of the OD and wall thickness.(Or according to customer`s request)
mechanical property
| Steel Grade | Tensile strength Rm N/mm2(MPa) | Yield Strength Rp0.2 N/mm2(MPa) | Elongation A % |
| Wall Thickness |
| ≤16mm | ＞16~30mm | ＞30mm |
| 10 | ≥335 | ≥205 | ≥195 | ≥185 | ≥24 |
| 15 | ≥375 | ≥225 | ≥215 | ≥205 | ≥22 |
| 20 | ≥410 | ≥245 | ≥235 | ≥225 | ≥20 |
| 25 | ≥450 | ≥275 | ≥265 | ≥255 | ≥18 |
| 35 | ≥510 | ≥305 | ≥295 | ≥285 | ≥17 |
| 45 | ≥590 | ≥335 | ≥325 | ≥315 | ≥14 |
| 20Mn | ≥450 | ≥275 | ≥265 | ≥255 | ≥20 |
| 25Mn | ≥490 | ≥295 | ≥285 | ≥275 | ≥18 |
| Q235 | A | 375~500 | ≥235 | ≥225 | ≥215 | ≥25 |
| B |
| C |
| D |
| Q275 | A | 415~540 | ≥275 | ≥265 | ≥255 | ≥22 |
| B |
| C |
| D |
| Q295 | A | 390~570 | ≥295 | ≥275 | ≥255 | ≥22 |
| B |
| Q345 | A | 470~630 | ≥345 | ≥325 | ≥295 | ≥20 |
| B |
| C | ≥21 |
| D |
| E |
| Q390 | A | 490~650 | ≥390 | ≥370 | ≥350 | ≥18 |
| B |
| C | ≥19 |
| D |
| E |
| Q420 | A | 520~680 | ≥420 | ≥400 | ≥380 | ≥18 |
| B |
| C | ≥19 |
| D |
| E |
| Q460 | C | 550~720 | ≥460 | ≥440 | ≥420 | ≥17 |
| D |
| E |
Test:
- Bending test
- Hardness test
- Impact test
- Squeezing test
- Non-destructive test
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