ASTM A36 ERW Pipe
Basic Overview
ASTM A36 ERW (Electric Resistance Welded) pipe is a carbon structural steel pipe manufactured by the electric resistance welding process . ASTM A36 is primarily a specification for carbon structural steel shapes, plates, and bars, but it is also commonly used for welded steel pipe in structural and low-pressure applications .
Name Explanation
| Part | Meaning |
|---|---|
| ASTM | ASTM International (American Society for Testing and Materials) |
| A36 | Standard specification for carbon structural steel – primarily for shapes, plates, and bars, but also applied to pipe |
| ERW | Electric Resistance Welded – pipe formed from steel coil and welded longitudinally without filler metal |
Key Features
| Feature | Description |
|---|---|
| Material Type | Low carbon structural steel |
| Yield Strength (min) | 250 MPa (36,300 psi) |
| Tensile Strength | 400-550 MPa (58,000-80,000 psi) |
| Elongation | Typically ≥20% |
| Manufacturing | Electric Resistance Welded (ERW) – high-frequency welding process |
| Size Range (ERW) | 12.7 mm to 609.6 mm (0.5" to 24") OD |
| Wall Thickness | 1.2 mm to 22 mm (SCH10 to SCH160) |
| Length | 3 m to 12 m standard; up to 18 m available |
Chemical Composition
| Element | Typical Range (max %) | Notes |
|---|---|---|
| Carbon (C) | 0.22-0.28% | Low carbon for good weldability |
| Manganese (Mn) | 0.70-1.10% | Provides strength |
| Silicon (Si) | 0.10-0.40% | Deoxidizer |
| Phosphorus (P) | 0.040% max | Controlled for weldability |
| Sulfur (S) | 0.050% max | Controlled for toughness |
Note: ASTM A36 does not mandate mandatory chemical composition for pipe; values shown are typical from manufacturer data .
Mechanical Properties
| Property | Value |
|---|---|
| Yield Strength (min) | 250 MPa (36,300 psi) |
| Tensile Strength | 400-550 MPa (58,000-80,000 psi) |
| Elongation (min) | 20% (varies by wall thickness) |
| Hardness | 85-185 HBW (typical) |
Dimensional Specifications
| Parameter | Range/Tolerance | Source |
|---|---|---|
| Outside Diameter | 12.7 mm to 609.6 mm (0.5" to 24") | |
| Wall Thickness | 1.2 mm to 22 mm (SCH10 to SCH160) | |
| Length | 3 m to 12 m standard; custom up to 18 m | |
| Tolerance (OD) | ±1% typical | |
| Tolerance (WT) | ±10% typical |
Testing Requirements
| Test Type | Purpose | Applicability |
|---|---|---|
| Chemical Analysis | Verify composition | Per heat |
| Tension Test | Confirm yield and tensile strength | Per lot |
| Flattening Test | Check ductility | For ERW pipe |
| Bend Test | Verify weld integrity | For ERW pipe |
| Hydrostatic Test | Pressure integrity verification | When specified |
Common Applications
| Application | Description |
|---|---|
| Structural Frames | Building columns, beams, support structures |
| Construction | Scaffolding, handrails, fencing |
| Bridge Components | Auxiliary structures, railings |
| Mechanical Equipment | Machine frames, conveyor supports |
| Low-Pressure Fluid Lines | Water, air, steam (non-critical) |
| Infrastructure Projects | Highway guardrails, lighting poles |
| Agricultural Applications | Greenhouse frames, irrigation supports |
International Equivalents
| Standard | Equivalent Grade |
|---|---|
| GB/T 700 | Q235B |
| JIS G3101 | SS400 |
| EN 10025 | S235JR |
| DIN | ST37-2 |
Key Advantages
| Advantage | Description |
|---|---|
| Excellent Weldability | Low carbon content makes A36 highly suitable for welding |
| Good Formability | Can be bent, rolled, and shaped without cracking |
| Cost-Effective | Economical structural steel option |
| Wide Availability | Commonly stocked by manufacturers globally |
| Versatile | Suitable for both structural and low-pressure applications |
| Proven Performance | Decades of use in construction and infrastructure |
Important Considerations
1. A36 is Primarily a Structural Specification
ASTM A36 is designed for structural applications (shapes, plates, bars)
When used for pipe, it is suitable for structural and low-pressure fluid service
For high-pressure applications, specify ASTM A53 Grade B or API 5L instead
2. ERW Manufacturing Benefits
The ERW process ensures consistent wall thickness and weld quality
Suitable for both structural and general engineering applications
Available with various coatings (black, varnish, galvanized)
3. Surface Treatment Options
Black (bare): Standard mill finish for general use
Varnish coating: Temporary protection during transport
Hot-dip galvanized: Enhanced corrosion protection for outdoor use
3LPE/FBE: For buried or corrosive environments
4. Service Life Estimates
With proper coating and maintenance:
Rural/indoor environments: 30+ years
Urban/outdoor environments: 20-25 years
Coastal/salt-spray environments: 15-18 years (with galvanized coating)
5. Limitations
Not certified for high-pressure oil/gas transmission (use API 5L)
Not suitable for high-temperature service above 400°C
For pressure applications, ensure proper wall thickness selection
Comparison with Other Specifications
| Property | ASTM A36 ERW | ASTM A53 Gr B ERW | API 5L X42 |
|---|---|---|---|
| Primary Use | Structural | General pressure | Oil/gas transmission |
| Yield Strength (min) | 250 MPa | 240 MPa | 290 MPa |
| Typical Application | Building frames, supports | Water, steam, air | Medium-pressure pipelines |
| Hydrostatic Test | Optional | Required | Required |
| Impact Testing | Not required | Optional | PSL2 requires |
Summary
ASTM A36 ERW pipe is a carbon structural steel pipe manufactured by the electric resistance welding process. With minimum yield strength of 250 MPa (36,300 psi) and tensile strength of 400-550 MPa, it is widely used in structural applications such as building frames, bridge components, scaffolding, and general construction .
Key features:
Low carbon content (0.22-0.28%) ensures excellent weldability
Available in diameters from 0.5" to 24" with wall thicknesses up to 22 mm
Can be supplied black, varnished, or hot-dip galvanized for corrosion protection
Equivalent to Q235B (Chinese), SS400 (Japanese), and S235JR (European) grades
Common applications include:
Structural steel frames and columns
Bridge auxiliary structures and railings
Scaffolding, handrails, and fencing
Machine frames and equipment supports
Low-pressure water and air lines
When ordering, specify: ASTM A36, ERW, Size (OD x WT), Length, End Finish, and Coating Requirements. For high-pressure or oil/gas applications, specify API 5L or ASTM A53 Grade B instead .
