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Help CenterGB/T 8162 Seamless Steel Tubes For Structural Purposes – Mechanical and General Engineering Structures
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GB/T 8162 Seamless Steel Tubes
For Structural Purposes – Mechanical and General Engineering Structures
Grades 10, 20, 35, 45, Q345, Q420, 40Cr, 15CrMo – Current Standard: GB/T 8162-2018
Product Overview
GB/T 8162 is the Chinese national standard for seamless steel tubes used for structural purposes – mechanical structures, general engineering structures, building frameworks, machinery components, bridge structures, and vehicle parts. These tubes are designed for applications where strength, toughness, and dimensional accuracy are required, without the pressure or fluid containment requirements of other specifications.
Standard Status:
Current standard: GB/T 8162-2018 (effective 2019-02-01)
Previous standard: GB/T 8162-2008 (effective 2009-04-01)
First issued: 1987
International reference: NEQ with EN 10297-1:2003
Key Applications:
Building and structural frameworks
Machinery components and mechanical parts
Bridge trusses and supports
Shipbuilding structures
Vehicle chassis and frames
Scaffolding and construction supports
Transmission towers
Agricultural machinery
✅ GB/T 8162-2018 compliant – Current standard
✅ Seamless construction – Hot rolled or cold drawn
✅ Wide grade selection – Carbon steel, HSLA steel, and alloy steel
✅ Excellent machinability – Suitable for cutting, drilling, welding
✅ Good strength-to-weight ratio – Economical structural material
✅ EN 10204 Type 3.1 MTC provided with full traceability
✅ Factory direct | Stock available | Fast delivery
Key Specifications
| Parameter | Details |
|---|---|
| Standard | GB/T 8162-2018 (current – supersedes GB/T 8162-2008) |
| Product Type | Seamless Steel Tube for Structural Purposes |
| Material Types | Carbon steel, Low alloy high strength steel (HSLA), Alloy steel |
| Steel Grades (Carbon) | 10, 20, 35, 45, Q235, Q275, Q295 |
| Steel Grades (HSLA) | Q345, Q390, Q420, Q460 |
| Steel Grades (Alloy) | 40Cr, 45Cr, 35CrMo, 42CrMo, 15CrMo, 12Cr1MoV |
| OD Range (Hot rolled) | 22mm – 610mm |
| OD Range (Cold drawn) | 6mm – 220mm |
| Wall Thickness (Hot rolled) | 2.0mm – 40mm |
| Wall Thickness (Cold drawn) | 0.5mm – 30mm |
| Length (Hot rolled) | 3m – 12m |
| Length (Cold drawn) | 2m – 10.5m |
| Delivery Condition | As-rolled, normalized, cold drawn, or heat treated |
| Surface Finish | Black / Bare / Oiled / Phosphated |
| End Finish | Plain / Beveled |
Steel Grade Overview – Carbon Steels
| Grade | Type | Tensile (MPa) | Yield (MPa) | Elongation (%) | Typical Application |
|---|---|---|---|---|---|
| 10 | Low carbon | 335-475 | ≥205 | ≥24 | Low stress structural parts |
| 20 | Low carbon | 410-550 | ≥245 | ≥20 | General structural – most popular |
| 35 | Medium carbon | 530-680 | ≥315 | ≥18 | Machinery parts, shafts |
| 45 | Medium carbon | ≥600 | ≥355 | ≥14 | High strength parts, gears |
💡 Grade 20 is the most popular carbon steel grade for general structural applications – offering excellent weldability and machinability at an economical price point.
Steel Grade Overview – HSLA Steels
| Grade | Type | Tensile (MPa) | Yield (MPa) | Elongation (%) | Low Temp Impact | Application |
|---|---|---|---|---|---|---|
| Q345 | HSLA | 470-630 | ≥345 | ≥20 | 27J at 0°C (C grade) | Most popular HSLA – bridges, buildings |
| Q390 | HSLA | 490-650 | ≥390 | ≥19 | 27J at 0°C | High strength structural |
| Q420 | HSLA | 520-680 | ≥420 | ≥18 | 27J at 0°C | High strength, heavy structures |
| Q460 | HSLA | 550-720 | ≥460 | ≥17 | 27J at 0°C | Ultra-high strength structures |
💡 Q345 (formerly 16Mn) is the most widely used HSLA grade – offering excellent strength-to-weight ratio and good low temperature toughness.
Steel Grade Overview – Alloy Steels
| Grade | Type | Tensile (MPa) | Yield (MPa) | Hardness (HB) | Application |
|---|---|---|---|---|---|
| 40Cr | Cr alloy | ≥810 | ≥590 | ~217 | Shafts, gears, high strength parts |
| 35CrMo | Cr-Mo alloy | ≥980 | ≥735 | ~229 | High strength, heavy duty |
| 42CrMo | Cr-Mo alloy | ≥1080 | ≥930 | ~241 | Very high strength components |
| 15CrMo | Cr-Mo alloy | 440-640 | ≥235 | ~179 | High temperature parts |
GB/T 8162 vs Other Chinese Standards – Comparison
| Feature | GB/T 8162 | GB/T 8163 | GB 3087 | GB 5310 |
|---|---|---|---|---|
| Primary Use | Structural applications | Fluid transport | Low-medium pressure boiler | High pressure boiler |
| Pressure containment | No requirement | Yes (fluid transport) | Yes (boiler) | Yes (high pressure) |
| Hydrostatic test | Not required | Required | Required | Required |
| Impact test | Not standard (by agreement) | No | Yes (alloy grades) | Yes (alloy grades) |
| Typical Applications | Building frames, machinery, bridges | Water/oil/gas pipelines | Industrial boilers | Power plants |
| Cost | $ | $$ | $$ | $$$ |
💡 For structural/mechanical applications, GB/T 8162 is the correct standard – it specifies mechanical properties suitable for load-bearing structures without pressure containment requirements .
Chemical Composition – Common Grades
| Grade | C (%) | Si (%) | Mn (%) | P max (%) | S max (%) | Cr (%) | Mo (%) |
|---|---|---|---|---|---|---|---|
| 20 | 0.17-0.24 | 0.17-0.37 | 0.35-0.65 | 0.030 | 0.030 | ≤0.25 | — |
| 45 | 0.42-0.50 | 0.17-0.37 | 0.50-0.80 | 0.030 | 0.030 | ≤0.25 | — |
| Q345 | ≤0.20 | ≤0.55 | 1.00-1.60 | 0.030 | 0.030 | ≤0.30 | — |
| Q420 | ≤0.20 | ≤0.55 | 1.00-1.70 | 0.030 | 0.030 | ≤0.30 | — |
| 40Cr | 0.37-0.44 | 0.17-0.37 | 0.50-0.80 | 0.030 | 0.030 | 0.80-1.10 | — |
| 35CrMo | 0.32-0.40 | 0.17-0.37 | 0.40-0.70 | 0.030 | 0.030 | 0.80-1.10 | 0.15-0.25 |
| 42CrMo | 0.38-0.45 | 0.17-0.37 | 0.50-0.80 | 0.030 | 0.030 | 0.90-1.20 | 0.15-0.25 |
📌 Low phosphorus and sulfur (≤0.030%) ensures good toughness and weldability for structural applications .
Applications – GB/T 8162 Structural Tubes
| Industry | Application | Recommended Grade | Typical Components |
|---|---|---|---|
| Building Construction | Building frames, columns, beams | 20, Q345 | Structural supports |
| Machinery | Mechanical parts, shafts, rollers | 20, 45, 40Cr | Machine components |
| Bridges | Bridge trusses, structural supports | Q345, Q420 | Load-bearing members |
| Shipbuilding | Hull structures, frames | Q345 | Structural integrity |
| Vehicle Manufacturing | Chassis, frames, axles | 20, Q345, 40Cr | Automotive parts |
| Agricultural Machinery | Equipment frames, supports | 20 | Durability |
| Scaffolding | Construction supports, formwork | 20 | Light structural |
| Power Transmission | Tower structures | Q345 | High strength |
| General Engineering | Frames, brackets, tooling | 20, 45 | Versatile applications |
Available Sizes – GB/T 8162 Structural Tubes
Hot Rolled Tubes (Most Common for Structural Applications):
| OD (mm) | WT Range (mm) | Typical Grade | Application |
|---|---|---|---|
| 22 – 60 | 2.0 – 8.0 | 20, Q345 | Small structural |
| 60 – 114 | 3.0 – 12.0 | 20, Q345 | General frames |
| 114 – 219 | 4.0 – 20.0 | 20, Q345 | Main structural members – most common |
| 219 – 273 | 5.0 – 25.0 | Q345, Q420 | Heavy columns |
| 273 – 426 | 6.0 – 30.0 | Q345, 40Cr | Large diameter structures |
| 426 – 610 | 8.0 – 40.0 | Q420 | Special heavy structures |
Cold Drawn Tubes (Precision for Mechanical Components):
| OD (mm) | WT Range (mm) | Typical Grade | Application |
|---|---|---|---|
| 6 – 25 | 0.5 – 4.0 | 20, 45, 40Cr | Precision shafts |
| 25 – 50 | 1.0 – 6.0 | 45, 40Cr | Mechanical parts |
| 50 – 76 | 2.0 – 10.0 | 45, 35CrMo | Gears, bearings |
| 76 – 108 | 2.5 – 12.0 | 40Cr, 42CrMo | High strength components |
💡 Most popular sizes for structural applications: 48.3mm, 60.3mm, 76mm, 89mm, 114mm, 168mm OD – Grade 20 or Q345 .
Key Advantages – GB/T 8162 Structural Tubes
| Feature | Benefit |
|---|---|
| Wide grade selection | Carbon steel, HSLA, alloy steel – one-stop sourcing |
| Seamless construction | No weld seam – consistent mechanical properties |
| Good weldability | Low carbon content (carbon grades) – standard procedures |
| Excellent machinability | Suitable for cutting, drilling, turning, milling |
| Q345 high strength | 345 MPa yield – reduces weight for same load capacity |
| Alloy grades available | 40Cr, 42CrMo for high strength mechanical parts |
| Economical | Lower cost than pressure-specific standards |
| Hot rolled or cold drawn | Choose based on dimensional requirements |
| Full traceability | EN 10204 3.1 MTC with heat number |
| Stock availability | Common grades and sizes ready to ship |
Quality Testing & Inspection – GB/T 8162
| Test | Method | Coverage | Requirement |
|---|---|---|---|
| Tensile Test | EN ISO 6892-1 | Per lot | Required |
| Flattening Test | Ductility | Per lot | Required |
| Chemical Analysis | Spectrometry | Per heat | Required |
| Dimensional Inspection | Micrometer | 100% | Required |
| Visual Examination | Direct | 100% | Required |
| Hydrostatic Test | Water pressure | By agreement | Optional |
| NDT (UT/ET) | Non-destructive | By agreement | Optional |
| Impact Test | Charpy | By agreement | For low temp applications |
| Hardness Test | Brinell/Rockwell | By agreement | For alloy grades |
📌 GB/T 8162 does not require hydrostatic or impact testing by default – these can be specified as supplementary requirements.
Dimensional Tolerances
| Deviation Level | Outer Diameter Tolerance | Application |
|---|---|---|
| D1 | ±1.5%, min ±0.75 mm | Standard tolerance |
| D2 | ±1.0%, min ±0.50 mm | Higher precision |
| D3 | ±0.75%, min ±0.30 mm | Precision applications |
| D4 | ±0.50%, min ±0.10 mm | Ultra-high precision |
Wall Thickness Tolerances:
| Manufacturing Method | Tolerance |
|---|---|
| Hot rolled | ±12.5% |
| Cold drawn | ±10.0% |
Length Tolerances (Fixed Length):
| Length (m) | Tolerance |
|---|---|
| ≤6 | +0.010m / -0 mm |
| >6 | +0.015m / -0 mm |
Mill Test Certificate – GB/T 8162
GB/T 8162 Certificate of Compliance – Standard
EN 10204 Type 3.1 MTC – Provided with heat number
EN 10204 Type 3.2 – Available upon request (third-party: SGS, BV, TUV)
Chemical analysis report – Per heat
Mechanical test reports – Tensile, flattening results
Dimensional inspection report
Traceability: Full traceability from melt to finished tube
Processing Services
| Service | Description | Applicable Grades |
|---|---|---|
| Cutting | Precision cutting to exact length | All grades |
| Beveling | For welding preparation (30°-37.5°) | All grades |
| Threading | NPT, BSP, or custom threads | Carbon grades |
| Bending | Cold or hot bending | 20, Q345 |
| Heat treatment | Normalizing, annealing, quenching, tempering | All grades |
| Surface coating | Oiling, painting, galvanized, phosphated | All grades |
| Machining | Turning, boring, drilling | All grades |
Packaging & Shipping
| Item | Details |
|---|---|
| Packaging | Hexagonal bundles or steel crates |
| Protection | Anti-rust oil + plastic end caps |
| Marking | Stencil/spray with Grade, size, heat number, GB/T 8162 |
| Documentation | MTC + test reports |
| Lead time | 7-15 days (stock: Grade 20, Q345), 20-30 days (custom sizes/grades) |
| Port | Tianjin / Shanghai / Guangzhou |
Why Choose Our GB/T 8162 Structural Tubes?
| Advantage | Description |
|---|---|
| Current standard | GB/T 8162-2018 compliant |
| Full grade range | 10, 20, 35, 45, Q345, Q420, 40Cr, 42CrMo – one-stop sourcing |
| Grade 20 and Q345 in stock | Most popular structural grades – ready to ship |
| Alloy grades available | 40Cr, 35CrMo, 42CrMo for high strength mechanical parts |
| Hot rolled or cold drawn | Both manufacturing methods available |
| Good machinability | Suitable for further processing |
| Full traceability | EN 10204 3.1 MTC with heat number |
| Global export | Shipped to construction and machinery projects worldwide |
Contact for Quote – GB/T 8162 Structural Tubes
Please provide the following details for your structural project:
Grade : 20 / Q345 / 40Cr / 42CrMo / Other _______
OD (mm) : _______
WT (mm) : _______
Length (m) : _______
Quantity : _______ (pieces / meters / tons)
Manufacturing : Hot rolled / Cold drawn
Application : Building / Machinery / Bridge / Vehicle / Other _______
Surface finish : Black / Oiled / Phosphated
Additional processing : Cutting / Bending / Heat treatment / None
Inspection : Standard / Third-party (SGS/BV/TUV)
📧 Email: yjhtrade@gmail.com
📞 WhatsApp: +86 15106174543
🌐 Website:
Reply within 24 hours.
FAQ – GB/T 8162 Structural Tubes
Q1: What is GB/T 8162 used for?
A: GB/T 8162 seamless steel tubes are used for structural purposes – mechanical structures, building frameworks, machinery components, bridge trusses, shipbuilding, and vehicle parts.
Q2: What is the current version of GB/T 8162?
A: GB/T 8162-2018 (effective 2019-02-01), superseding GB/T 8162-2008.
Q3: What is the difference between GB/T 8162 and GB/T 8163?
A: GB/T 8162 – structural applications (building frames, machinery, bridges) – no pressure requirement. GB/T 8163 – fluid transport (water, oil, gas) – requires hydrostatic testing.
Q4: What is the most popular grade in GB/T 8162?
A: Grade 20 for carbon steel (410-550 MPa tensile, ≥245 MPa yield). Q345 for HSLA steel (470-630 MPa tensile, ≥345 MPa yield) – widely used for bridges and heavy structures.
Q5: What is Q345 equivalent to in other standards?
A: Q345 (formerly 16Mn) is approximately equivalent to S355JR/J0/J2 in EN 10025-2 and A572 Grade 50 in ASTM – high strength low alloy structural steel.
Q6: Can GB/T 8162 tubes be used for pressure applications?
A: Not recommended – GB/T 8162 is for structural purposes without pressure containment requirements. For fluid transport, use GB/T 8163. For pressure vessels, use other standards.
Q7: Is hydrostatic testing required for GB/T 8162?
A: No – GB/T 8162 does not require hydrostatic testing by default. It can be specified as a supplementary requirement if needed.
Q8: What are the available manufacturing methods?
A: Hot rolled – standard for larger diameters; Cold drawn – precision dimensions for mechanical components.
Q9: What are the typical length ranges?
A: Hot rolled: 3-12m; Cold drawn: 2-10.5m.
Q10: Do you provide third-party inspection?
A: Yes. SGS, BV, TUV, or any customer-specified agency.
Q11: Can GB/T 8162 tubes be welded?
A: Yes – carbon steel grades (10, 20) have excellent weldability. Q345 and alloy grades may require preheat.
Q12: Do you offer free samples?
A: 30cm sample available for common grades (Grade 20, Q345). Shipping fee applies.
Related Products – Structural Piping
GB/T 8162 – Structural tubing (this product)
GB/T 8163 – Fluid transport tubing
GB 3087 – Low-medium pressure boiler tubes
GB 5310 – High pressure boiler tubes
GB/T 1591 – High strength low alloy structural steel (Q345, Q420)
GB/T 699 – High quality carbon structural steel
Tags: GB/T 8162 Structural Steel Tube Seamless Steel Pipe Mechanical Structure Building Frame Bridge Steel Chinese Standard Structural Tubing
Quick Reference – GB/T 8162 Grade Selection
| Grade | Type | Tensile (MPa) | Yield (MPa) | Best Application | Cost |
|---|---|---|---|---|---|
| 20 | Carbon steel | 410-550 | ≥245 | General structural | $ |
| Q345 | HSLA steel | 470-630 | ≥345 | Bridges, heavy structures | $$ |
| 45 | Carbon steel | ≥600 | ≥355 | Machinery parts, shafts | $$ |
| 40Cr | Alloy steel | ≥810 | ≥590 | High strength mechanical | $$$ |
| 42CrMo | Alloy steel | ≥1080 | ≥930 | Very high strength | $$$$ |
GB/T 8162 vs GB/T 8163 – Selection Guide
| Feature | GB/T 8162 (Structural) | GB/T 8163 (Fluid Transport) |
|---|---|---|
| Primary application | Frames, machinery, bridges | Water, oil, gas pipelines |
| Hydrostatic test | Not required | Required |
| Pressure rating | Not applicable | Pressure-containing |
| Weldability | Excellent (carbon grades) | Excellent |
| Cost | $ | $$ |
| When to use | Load-bearing structures | Fluid distribution |
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