ASTM A252 Spiral Welded Steel Pipe (SSAW)
Basic Overview
ASTM A252 Spiral Submerged Arc Welded (SSAW) steel pipe is a carbon steel pipe pile specifically designed for foundation and structural support applications. Unlike pressure pipes (e.g., API 5L), these pipes serve as permanent load-carrying members or as shells for cast-in-place concrete piles .
The SSAW manufacturing process allows for large-diameter pipes to be produced economically, making ASTM A252 spiral welded pipe the preferred choice for marine structures, bridge foundations, high-rise buildings, and land reclamation projects .
Name Explanation
| Part | Meaning |
|---|---|
| ASTM | ASTM International (American Society for Testing and Materials) |
| A252 | Standard specification for welded and seamless steel pipe piles |
| Grades | Grade 1, Grade 2, Grade 3 – three strength levels available |
| SSAW | Spiral Submerged Arc Welding – double-sided welding with filler metal; weld seam runs continuously in a spiral along the pipe length |
Key Specifications
| Attribute | Description |
|---|---|
| Standard | ASTM A252 / A252M – "Standard Specification for Welded and Seamless Steel Pipe Piles" |
| Manufacturing Process | Spiral Submerged Arc Welding (SSAW) – double-sided automatic welding |
| Grades | Grade 1, Grade 2, Grade 3 – Grade 2 is most common |
| Size Range (SSAW) | 219 mm to 4064 mm (8" to 160") OD |
| Wall Thickness | 3.2 mm to 60 mm (common range 6-25.4 mm) |
| Length | 6 m to 24 m standard; up to 32 m available |
| End Finishes | Plain ends, beveled ends (30° bevel), threaded |
Chemical Composition (All Grades)
ASTM A252 specifies only maximum limits for phosphorus. All three grades share the same composition limits :
| Element | Maximum % |
|---|---|
| Carbon (C) | 0.26% (typical, not mandated) |
| Manganese (Mn) | 1.60% (typical, not mandated) |
| Silicon (Si) | 0.45% (typical, not mandated) |
| Phosphorus (P) | 0.050% (mandatory) |
| Sulfur (S) | 0.030% (typical) |
Note: The standard only mandates maximum phosphorus. Chemical composition values shown are typical from manufacturer data .
Mechanical Properties Comparison
| Grade | Yield Strength (min) | Tensile Strength (min) | Elongation (min) | Strength vs. Grade 1 |
|---|---|---|---|---|
| Grade 1 | 205 MPa (30,000 psi) | 345 MPa (50,000 psi) | 30% | Baseline |
| Grade 2 | 240 MPa (35,000 psi) | 415 MPa (60,000 psi) | 25% | +17% yield |
| Grade 3 | 310 MPa (45,000 psi) | 455 MPa (66,000 psi) | 20% | +51% yield |
Source:
Dimensional Tolerances
| Parameter | Tolerance |
|---|---|
| Outside Diameter (OD ≤ 508mm) | ±1% or ±1.0mm (whichever is greater) |
| Outside Diameter (OD > 508mm) | ±1% or ±4.0mm (whichever is greater) |
| Wall Thickness | +15% / -12.5% of nominal |
| Weight | +15% / -5% of theoretical weight |
| Straightness | ≤ 0.1% of total length |
Typical Size Availability (SSAW):
| OD (inch) | OD (mm) | Wall Thickness Range (mm) |
|---|---|---|
| 16" | 406 | 6.0 - 14.0 |
| 20" | 508 | 6.0 - 16.0 |
| 24" | 610 | 6.0 - 18.0 |
| 30" | 762 | 7.0 - 21.0 |
| 36" | 914 | 8.0 - 24.0 |
| 40" | 1016 | 8.0 - 26.0 |
| 48" | 1219 | 9.0 - 28.0 |
| 56" | 1422 | 10.0 - 29.0 |
| 60" | 1524 | 10.0 - 29.0 |
| 64" | 1626 | 10.0 - 30.0 |
| 72" | 1829 | 10.0 - 30.0 |
SSAW Manufacturing Process
Spiral welded pipes under ASTM A252 are produced using the following process :
| Step | Description |
|---|---|
| 1. Raw Material Preparation | Steel coils meeting ASTM A252 chemistry requirements are leveled, trimmed, and planed |
| 2. Edge Preparation | Strip edges are milled for proper welding |
| 3. Spiral Forming | Steel strip is continuously formed into a cylindrical shape at a specific helix angle |
| 4. Submerged Arc Welding | Double-sided automatic submerged arc welding (inside and outside) creates the spiral seam with penetration depth ≥1.5mm |
| 5. Weld NDT | 100% ultrasonic automatic flaw detection of the weld seam |
| 6. Hydrostatic Testing | Each pipe tested at 2× working pressure for ≥15 seconds |
| 7. End Finishing | Beveled ends (30° angle) for field welding |
| 8. Coating | Anti-corrosion coating as required (epoxy, 3LPE, coal tar epoxy) |
Testing & Inspection Requirements
| Test Type | Requirement | Notes |
|---|---|---|
| Chemical Analysis | Per heat lot | Phosphorus limit enforced |
| 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 | 2× working pressure, ≥15 seconds |
| Ultrasonic Inspection (UT) | 100% of weld seam | Continuous automatic flaw detection |
| Dimensional Inspection | 100% | Per ASTM A252 tolerances |
| Mill Test Certificate | EN 10204 Type 3.1B | Provided with full test results |
Applications
ASTM A252 spiral welded pipes are used in demanding foundation applications :
| Application | Description |
|---|---|
| Marine Structures | Ports, wharves, docks, seawalls, offshore platforms |
| Bridge Foundations | Pier and abutment support for cross-river/sea bridges |
| High-Rise Building Foundations | Core tube pile foundations for skyscrapers (single pile capacity ≥8000kN) |
| Land Reclamation | Coastal embankments, reclamation bulkheads |
| Industrial Plant Foundations | Heavy equipment foundation piles |
| Temporary Works | Foundation pit support, construction platforms |
| Transmission Tower Foundations | Soil corrosion zones with 3PE coating |
Grade Selection Guidance
| Grade | Yield Strength | Typical Application |
|---|---|---|
| Grade 1 | 205 MPa (30 ksi) | Light-load applications, good soil conditions, temporary structures |
| Grade 2 | 240 MPa (35 ksi) | Most common – medium-rise buildings, bridge foundations, general piling |
| Grade 3 | 310 MPa (45 ksi) | Heavy-load applications, large bridges, offshore platforms, seismic zones |
For most general foundation applications, Grade 2 is the standard choice.
Coating Options
| Coating Type | Best For | Key Features |
|---|---|---|
| 3LPE (3-layer polyethylene) | Buried piles | 50+ year service life, excellent corrosion protection |
| FBE (Fusion Bonded Epoxy) | Marine/splash zone | 30+ year service life, strong adhesion |
| Coal Tar Epoxy | Marine environments | Heavy-duty protection |
| Concrete Weight Coating (CWC) | Offshore/subsea | Negative buoyancy, mechanical protection |
| Epoxy Resin / Glass Flake | Corrosive environments | Dry film ≥300μm for salt corrosion resistance |
| Bitumen Coating | Buried service | Cost-effective protection |
| Hot-dip Galvanized | Above-ground | Lifespan 20+ years in offshore environments |
SSAW vs. LSAW vs. ERW Comparison for ASTM A252
| Aspect | SSAW (Spiral) | LSAW (Longitudinal) | ERW |
|---|---|---|---|
| Cost (per ton) | Lowest (100% plate utilization) | Highest | Medium |
| OD Range | 219-4064 mm (8-160") | 406-1626 mm (16-64") | Up to 610 mm (24") |
| Wall Thickness | Up to 60 mm | Up to 63.5 mm | Limited |
| Production Speed | Fast (continuous spiral welding) | Slow (JCOE/UOE forming) | Medium |
| Typical Application | Ports, land reclamation, large-diameter piling | Heavy-wall, high-strength piling | Smaller diameter piling |
| Axial Strength | Spiral weld disperses stress – 15-20% higher than straight seam | Good | Standard |
Source:
Advantages of SSAW for ASTM A252 Piling
| Advantage | Description |
|---|---|
| Large Diameter Capability | SSAW produces pipes up to 4000mm OD – ideal for large-diameter piling |
| Cost-Effective | Most economical for large diameters; 35% lower cost than seamless, 15% lower than Grade 3 |
| Superior Axial Strength | Spiral weld seam disperses stress – 15-20% higher axial compressive strength than straight seam |
| Long Lengths | Up to 32m lengths reduce field splicing requirements |
| High Weld Integrity | 100% UT inspection of weld seam; double-sided welding ensures full penetration |
| Hydrostatic Testing | Each pipe tested at 2× working pressure – distinguishes from ASTM A252 which does not mandate this |
| Multiple Coating Options | FBE, 3LPE, coal tar epoxy, CWC for marine/corrosive environments |
Important Considerations
1. ASTM A252 is for Piling, NOT Pressure
ASTM A252 is specifically for foundation piling applications
Pipes are filled with concrete, not used for fluid conveyance
Hydrostatic testing is optional per ASTM A252, but most manufacturers provide it
2. Grade 2 is the Standard Choice
Grade 2 is the most commonly specified grade for general piling applications
Grade 1 is for light-load applications; Grade 3 for heavy-load, demanding conditions
3. SSAW Size Limitations
SSAW manufacturing for ASTM A252 is typically available from 8" to 160" OD
Smaller diameters (under 8") are typically produced by ERW methods
4. Corrosion Protection for Marine Environments
For marine structures, specify epoxy resin coating (dry film ≥300μm) or 3LPE
For offshore, consider concrete weight coating (CWC) for negative buoyancy
5. End Preparation for Field Welding
Beveled ends (30° bevel) standard for field welding
Root face: 1.6±0.8mm
Driving shoes available for hard driving conditions
6. Third-Party Inspection
Available inspection services include SGS, BV, Lloyds
7. Mill Test Certificate
Typically provided as EN 10204 Type 3.1B with full test results
Summary
ASTM A252 Spiral Submerged Arc Welded (SSAW) steel pipe is the standard specification for large-diameter steel pipe piles used in foundation and marine construction. With three strength grades (Grade 1: 205 MPa, Grade 2: 240 MPa, Grade 3: 310 MPa) and sizes up to 4000mm OD, these pipes are the preferred choice for ports, bridges, high-rise buildings, and land reclamation projects .
Key features:
Material standard: ASTM A252 – American standard for steel pipe piles
Grades: Grade 1 (30 ksi), Grade 2 (35 ksi) – most common, Grade 3 (45 ksi)
SSAW manufacturing produces pipes from 8" to 160" OD with wall thickness up to 60 mm
Double-sided welding creates a single high-quality weld nugget
100% ultrasonic inspection of weld seam ensures quality
Hydrostatic testing at 2× working pressure (manufacturer standard)
Spiral weld design provides 15-20% higher axial compressive strength than straight seam
Cost-effective – most economical for large-diameter piling applications
Common applications include:
Marine structures (ports, wharves, docks, seawalls)
Bridge foundations and pier supports
High-rise building deep foundations
Land reclamation and coastal embankments
Industrial plant foundations and temporary works
When ordering, specify: ASTM A252, Grade [1/2/3], SSAW (Spiral Submerged Arc Welded), Size (OD x WT), Length, End Finish (plain/beveled), Coating Requirements (FBE/3LPE/epoxy), and Mill Test Certificate to EN 10204 Type 3.1B. For most general piling applications, Grade 2 is the recommended default .
