GB/T 13793 Longitudinally Electric Resistance Welded Steel Pipe
Basic Overview
GB/T 13793 is the Chinese national standard for straight seam electric resistance welded (ERW) steel pipes. The standard specifies requirements for longitudinally welded pipes manufactured by the electric resistance welding process, used primarily for general structural, mechanical, and engineering purposes .
Key Specifications
| Attribute | Description |
|---|---|
| Standard Number | GB/T 13793 |
| Full Title | "Straight seam electric resistance welded steel pipes" (直缝电焊钢管) |
| Latest Version | GB/T 13793-2016 (effective July 1, 2017) |
| Previous Version | GB/T 13793-2008 (superseded) |
| Pipe Type | Longitudinal/straight seam electric resistance welded (ERW) – weld seam parallel to pipe axis |
| Primary Application | General structural purposes, mechanical engineering, ordinary structural use |
| Manufacturing | Electric Resistance Welding (ERW) – high-frequency welding without filler metal |
Applicable Steel Grades
GB/T 13793 pipes can be manufactured from the following steel grades :
| Grade | Standard | Typical Use |
|---|---|---|
| Q195 | GB/T 700 | Low strength, general purpose |
| Q215A / Q215B | GB/T 700 | General structural |
| Q235A / Q235B | GB/T 700 | Most common – general structural |
| Q275A / Q275B | GB/T 700 | Higher strength requirements |
| Q295A / Q295B | GB/T 1591 | Low-alloy high-strength |
| Q345A / Q345B | GB/T 1591 | High-strength structural |
| 10, 20 | GB/T 699 | High-quality carbon steel |
| Q355B / Q355C | GB/T 1591 (newer) | High-strength low-alloy |
Chemical Composition (Typical - Q235B)
| Element | Maximum % | Notes |
|---|---|---|
| Carbon (C) | 0.20% | Low carbon for good weldability |
| Manganese (Mn) | 1.40% | Provides strength |
| Silicon (Si) | 0.35% | Deoxidizer |
| Phosphorus (P) | 0.045% | Controlled for weldability |
| Sulfur (S) | 0.045% | Controlled for toughness |
*Note: Actual limits vary by grade. Refer to GB/T 700 or GB/T 1591 for specific grade requirements.*
Mechanical Properties (Typical - Q235B)
| Property | Value |
|---|---|
| Yield Strength (t ≤ 16mm) | ≥ 235 MPa |
| Tensile Strength | 370-500 MPa |
| Elongation | ≥ 15-20% (varies by thickness) |
| Hardness | As specified |
Dimensional Tolerances
| Parameter | Tolerance |
|---|---|
| Outside Diameter (D ≤ 48.3mm) | ±0.5 mm |
| Outside Diameter (48.3mm < D ≤ 273.1mm) | ±1% D |
| Outside Diameter (D > 273.1mm) | ±0.75% D |
| Wall Thickness | ±10% of nominal |
| Length | +50mm / -0mm |
| Straightness | ≤ 0.1% of total length (typical) |
Manufacturing Process
Longitudinally electric resistance welded pipes are produced using :
Uncoiling – Steel coil is uncoiled and leveled
Edge Preparation – Strip edges are milled for proper welding
Forming – Steel strip is cold-formed into cylindrical shape
Electric Induction Welding – High-frequency welding joins edges without filler metal
Heat Treatment – Weld seam normalized to refine grain structure
Sizing – Pipe passes through sizing rolls to achieve final dimensions
NDT – 100% non-destructive testing of weld seam (ultrasonic or eddy current)
Hydrostatic Testing – Each pipe individually tested (when specified)
Finishing – End processing, coating, and marking
Testing & Inspection Requirements
| Test Type | Requirement | Notes |
|---|---|---|
| Chemical Analysis | Per heat lot | Verifies composition per GB/T 700 or GB/T 1591 |
| Tensile Test | Per lot | Verifies yield and tensile strength |
| Flattening Test | Required | Checks ductility and weld integrity |
| Bend Test | Required | Verifies weld integrity |
| Hydrostatic Test | Each pipe | When specified by purchaser |
| NDT (Ultrasonic/Eddy Current) | Weld seam inspection | Standard practice |
| Dimensional Inspection | 100% | Per GB/T 13793 tolerances |
| Visual Inspection | 100% | Surface condition, weld appearance |
| Mill Test Certificate | Provided | With full test results |
Common Applications
| Application | Description |
|---|---|
| General Structural Engineering | Building frames, columns, trusses for industrial plants, warehouses |
| Mechanical Manufacturing | Machinery components, equipment frames, conveyor systems |
| Construction | Scaffolding, handrails, fencing, supports |
| Low-Pressure Fluid Lines | Water, air, and steam (non-critical) |
| Agricultural Applications | Greenhouse frames, irrigation supports |
| Vehicle Manufacturing | Chassis components, structural parts |
| Furniture | Metal frames, shelving, office furniture |
Comparison with Related Standards
| Standard | Pipe Type | Manufacturing | Primary Application |
|---|---|---|---|
| GB/T 13793 | Longitudinal ERW | Electric Resistance Welded | General structural, mechanical engineering |
| GB/T 3091 | Longitudinal ERW, Spiral SAW | ERW + SAW | Low-pressure fluid transmission |
| GB/T 9711 | Longitudinal, Spiral, Seamless | ERW, SAW, SMLS | Petroleum and natural gas pipelines |
| SY/T 5037 | Spiral SAW | Submerged Arc Welded | Low-pressure fluid pipelines |
| GB/T 14976 | Seamless | SMLS | Fluid transport (stainless) |
Key Advantages
| Advantage | Description |
|---|---|
| Cost-Effective | ERW process is economical for small to medium diameters |
| Good Weldability | Low carbon content ensures excellent weldability |
| Consistent Quality | Automated welding ensures uniform weld quality |
| Dimensional Accuracy | Tight tolerances on OD and wall thickness |
| Wide Material Range | Available in multiple grades from Q195 to Q345 |
| Proven Performance | Decades of use in structural and mechanical applications |
Important Considerations
1. GB/T 13793 is for Longitudinal ERW Only
This standard applies only to straight seam electric resistance welded pipes
Does not apply to spiral welded (SSAW) pipes or seamless pipes
2. Not for High-Pressure Fluid Transmission
GB/T 13793 is designed for structural and mechanical applications
For high-pressure fluid transmission, specify GB/T 9711 or API 5L
3. Standard Version
GB/T 13793-2016 is the current version (effective July 1, 2017)
Previous version GB/T 13793-2008 is superseded
4. Grade Selection
Q235B is the most common grade for general structural applications
For higher strength requirements, specify Q345 or Q355 grades
5. Size Range
Typical size range for GB/T 13793: small to medium diameters (up to ~610 mm OD)
For larger diameters, consider spiral welded pipes under other standards
6. Coating Options
Black (bare): Standard mill finish
Varnish / Anti-rust oil: Temporary protection
Galvanized: For corrosion protection (by agreement)
FBE/3LPE: For buried applications (by agreement)
International Approximations
| Standard | Equivalent Grade | Notes |
|---|---|---|
| ASTM A53 | Type E, Grade B | Similar ERW pipe |
| ASTM A500 | Grade B or C | Structural tubing |
| EN 10219 | S235JRH, S275J0H, S355J2H | European structural hollow sections |
| JIS G3444 | STK400, STK490 | Japanese structural pipes |
Summary
GB/T 13793 longitudinally electric resistance welded steel pipe is the standard specification for straight seam ERW pipes used in general structural and mechanical engineering applications in China.
Key features:
Standard: GB/T 13793-2016 – "Straight seam electric resistance welded steel pipes"
Pipe type: Longitudinal/straight seam electric resistance welded (ERW)
Grades: Q195, Q215, Q235, Q275, Q295, Q345, Q355, 10, 20
Primary application: General structural purposes, mechanical engineering
Manufacturing: Cold-formed, high-frequency ERW
Weld seam: Longitudinal (parallel to pipe axis)
Size range: Small to medium diameters (typically ≤ 610 mm OD)
100% NDT of weld seam (ultrasonic or eddy current)
Excellent weldability and good formability
Common applications include:
General structural engineering (building frames, columns, trusses)
Mechanical manufacturing (machinery components, equipment frames)
Construction (scaffolding, handrails, fencing)
Low-pressure fluid lines (non-critical)
Agricultural and vehicle applications
When ordering, specify: GB/T 13793-2016, Grade (e.g., Q235B), ERW (longitudinally welded), Size (OD x WT), Length, End Finish (plain/beveled), Coating Requirements, and Mill Test Certificate.
For high-pressure fluid transmission, specify GB/T 9711 or API 5L instead. For large diameters (>610 mm), consider spiral welded pipes under GB/T 3091 or SY/T 5037 .
