GB/T 3091 Spiral Submerged Arc Welded Steel Pipe (SSAW)
Basic Overview
GB/T 3091 is the Chinese national standard titled "Welded steel pipes for low pressure liquid delivery" . This standard explicitly includes spiral submerged arc welded (SSAW/SAWH) pipes as one of the permitted manufacturing methods for low-pressure fluid transmission applications .
Key Specifications
| Attribute | Description |
|---|---|
| Standard Number | GB/T 3091 |
| Latest Version | GB/T 3091-2025 (effective October 1, 2025) |
| Current Version | GB/T 3091-2015 (until October 2025) |
| Full Title | "Welded steel pipes for low pressure liquid delivery" / "低压流体输送用焊接钢管" |
| Scope | Water, air, steam, and gas low-pressure fluid transmission |
| Pipe Types Covered | HFW (ERW), SAWL (LSAW), and SAWH (SSAW - spiral submerged arc welded) |
| Application | Low-pressure fluid transmission (typically ≤1.6 MPa) |
Steel Grades (Materials)
| Grade | Yield Strength (min) | Tensile Strength (min) | Elongation % | Typical Use |
|---|---|---|---|---|
| Q195 | 195 MPa | 315 MPa | 20 | Light duty, low pressure |
| Q215 | 215 MPa | 335 MPa | 20 | General purpose |
| Q235B | 235 MPa | 370 MPa | 20 | Most common - general service |
| Q275 | 275 MPa | 410 MPa | 18 | Higher strength requirements |
| Q355B | 355 MPa | 470 MPa | 18 | High-strength applications |
*Note: Q355B is a new addition in GB/T 3091-2025 .*
SSAW Manufacturing Process
Spiral submerged arc welded pipes under GB/T 3091 are produced using :
Raw Material: Hot-rolled steel coil (grades Q195, Q215, Q235, Q275, Q355)
Forming: Steel strip is continuously spiral-formed at room temperature
Welding: Double-sided automatic submerged arc welding (inside and outside)
NDT: 100% ultrasonic or X-ray inspection of weld seam
Hydrostatic Test: Each pipe individually tested
Finishing: End beveling, coating as required
Dimensional Tolerances (SAWH)
| Parameter | Size Range | 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 |
Typical Size Range for SSAW: 219 mm to 4064 mm (8" to 160") OD .
Key Applications
| Application | Description |
|---|---|
| Water Supply | Municipal and industrial water transmission |
| Natural Gas | Low-pressure gas distribution networks |
| Steam Lines | Low-pressure heating steam |
| Compressed Air | Industrial air systems |
| Fire Protection | Fire water mains (galvanized) |
| Structural Use | Piling, scaffolding, supports |
*Note: Galvanized pipes under GB/T 3091 are commonly called "white pipe" .*
GB/T 3091 vs. Other Standards
| Standard | Application | Pressure Rating |
|---|---|---|
| GB/T 3091 | Low-pressure fluid transmission (water, air, steam, gas) | ≤1.6 MPa typical |
| GB/T 9711 | Petroleum and natural gas pipelines | Medium to high pressure |
| GB/T 14291 | Mine fluid service (slurry, dewatering) | Low pressure, abrasive service |
| SY/T 5037 | General low-pressure fluid pipelines | Low pressure |
Version Updates
| Version | Status | Key Changes |
|---|---|---|
| GB/T 3091-2025 | Effective Oct 1, 2025 | Adds Q355B grade, extended hydrostatic test time, updated tolerances |
| GB/T 3091-2015 | Current (until Oct 2025) | Replaced 2008 version |
| GB/T 3091-2008 | Superseded | Replaced by 2015 version |
| GB/T 3091-2001 | Obsolete | Historical version |
Coating Options
GB/T 3091 pipes can be supplied with:
| Coating Type | Application |
|---|---|
| Black (bare) | Standard mill finish |
| Galvanized (Hot-dip) | Corrosion protection for water/gas lines |
| Varnish / Anti-rust oil | Temporary protection |
| FBE / 3LPE | Buried pipelines (by agreement) |
Key Advantages of SSAW under GB/T 3091
| Advantage | Description |
|---|---|
| Cost-Effective | More economical than LSAW or seamless for large diameters |
| Large Diameter Capability | Produces pipes up to 160" OD |
| Long Lengths | Up to 18m standard lengths reduce field joints |
| Versatile | Suitable for water, gas, steam, and structural applications |
| Galvanizing Option | Hot-dip galvanized available for corrosion protection |
| Widely Available | Common stock item from Chinese manufacturers |
Important Considerations
1. Pressure Limitations
GB/T 3091 is specifically for low-pressure fluid transmission (typically ≤1.6 MPa). For higher pressures, specify GB/T 9711 or API 5L.
2. SSAW vs. ERW for GB/T 3091
SSAW (Spiral): Preferred for larger diameters (> 219mm / 8")
ERW (Straight seam): Preferred for smaller diameters (≤ 219mm / 8")
3. Standard Version
GB/T 3091-2025 will be effective October 1, 2025
Until then, GB/T 3091-2015 is the current valid version
4. Q355B Grade (New in 2025 version)
The 2025 version adds Q355B low-alloy steel grade with:
Yield strength: ≥355 MPa (for thickness ≤16mm)
Tensile strength: 470-630 MPa
5. Weld Seam NDT
100% ultrasonic or X-ray inspection of the spiral weld seam is standard
Hydrostatic testing required for each pipe
Summary
GB/T 3091 spiral submerged arc welded steel pipe is the standard choice for large-diameter, low-pressure fluid transmission applications in China. It covers water, air, steam, and gas pipelines, as well as galvanized pipes for corrosion protection.
Key features:
Covers spiral submerged arc welded (SAWH) pipes explicitly
Applicable to low-pressure fluid transmission (water, air, steam, gas)
Available grades: Q195, Q215, Q235B, Q275, Q355B (Q355B new in 2025)
SSAW process suitable for large diameters (219mm to 4064mm / 8" to 160")
100% NDT of weld seam and hydrostatic testing required
Galvanized option available for corrosion protection
Current standard: GB/T 3091-2015; New standard: GB/T 3091-2025 (effective Oct 1, 2025)
When ordering, specify: GB/T 3091, Grade (e.g., Q235B), SSAW (spiral submerged arc welded), Size (OD x WT), Length, End Finish (plain/beveled), Coating (black/galvanized), and Standard Version (2015 or 2025).
