ASTM A252 Grade 1 Spiral Welded Steel Pipe (SSAW)
Basic Overview
ASTM A252 Grade 1 Spiral Submerged Arc Welded (SSAW) steel pipe is the entry-level grade for steel pipe piles used in foundation and structural applications . It is specifically designed for light-load foundation piling where the lowest strength grade is sufficient . Unlike pressure pipes (e.g., ASTM A53), these pipes serve as permanent load-carrying members or as shells for cast-in-place concrete piles .
Name Explanation
| Part | Meaning |
|---|---|
| ASTM | ASTM International (American Society for Testing and Materials) |
| A252 | Standard specification for welded and seamless steel pipe piles |
| Grade 1 | The lowest strength grade – minimum yield strength of 30,000 psi (205 MPa) |
| 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" [citation:5, citation:6] |
| Primary Function | Structural foundation support – not for fluid pressure containment |
| Manufacturing Process | Spiral Submerged Arc Welding (SSAW) – double-sided automatic welding |
| Minimum Yield Strength | 205 MPa (30,000 psi) [citation:1, citation:6] |
| Minimum Tensile Strength | 345 MPa (50,000 psi) [citation:1, citation:6] |
| Minimum Elongation | 30% (for wall thickness ≥ 7.9mm) |
| Size Range (SSAW) | 219 mm to 3000 mm (8" to 118") OD – up to 4000 mm available [citation:1, citation:7] |
| Wall Thickness | 3.2 mm to 60 mm (common range 6-25.4 mm) [citation:1, citation:7] |
| Length | 6 m to 32 m standard; custom lengths available [citation:2, citation:7] |
| End Finishes | Plain ends (PE) standard; beveled ends for field welding |
Chemical Composition
ASTM A252 specifies only maximum limits for phosphorus. All three grades share the same composition limits [citation:2, citation:6]:
| 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 focuses on mechanical properties rather than strict chemical composition. The steel shall contain no more than 0.050% phosphorus [citation:2, citation:6].
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: [citation:1, citation:6]
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:
| 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 requirements are leveled and edge-milled |
| 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 |
| 5. Weld NDT | 100% ultrasonic inspection of the weld seam |
| 6. Hydrostatic Testing | Optional – may be performed by agreement |
| 7. End Finishing | Plain or beveled ends for field welding |
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 | Mandatory – transverse weld specimen bent without cracking | Key test for piling pipes |
| Hydrostatic Test | Optional | Not mandatory for piling pipes |
| Ultrasonic Inspection | 100% of weld seam | Standard practice for SSAW |
| Dimensional Inspection | 100% | Per ASTM A252 tolerances |
| Mill Test Certificate | EN 10204 Type 3.1B | Provided with full test results |
Applications
Grade 1 is the most economical choice for light-load foundation applications :
| Application | Description |
|---|---|
| Light Structural Foundations | Residential and small commercial buildings |
| Good Soil Conditions | Where bearing capacity ≤120 kN/m² |
| Temporary Shoring | Excavation support and temporary structures |
| Shallow Piling | Piles that do not require high load capacity |
| Small Bridges | Bridges without large load requirements |
| Light-Duty Marine Structures | Non-critical docks and piers |
Grade Selection Guidance
| Grade | Yield Strength | Best For |
|---|---|---|
| Grade 1 | 205 MPa (30 ksi) | Light-load applications, good soil conditions, temporary structures, most economical |
| 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 |
Advantages of SSAW for Grade 1 Piling
| Advantage | Description |
|---|---|
| Cost-Effective | Most economical option for large-diameter piling applications |
| Large Diameter Capability | SSAW produces pipes from 8" to 160" OD – ideal for large-diameter piling |
| Long Lengths | Up to 32m lengths reduce field splicing requirements |
| High Weld Integrity | 100% UT inspection of weld seam ensures quality |
| Spiral Stress Distribution | Spiral weld disperses stress more evenly during pile driving |
| Material Efficiency | Can use narrower steel strips to produce large-diameter pipes |
Important Considerations
1. Grade 1 vs. Higher Grades
Grade 1 is the most economical but has the lowest strength
For most permanent foundation applications, Grade 2 is the more common and recommended grade
For heavy-load projects, Grade 3 provides the highest strength
2. No Hydrostatic Testing Required
ASTM A252 does not require hydrostatic testing because piling pipes are filled with concrete and not used for fluid conveyance
This differs from pressure pipe standards like API 5L or ASTM A53
3. Bend Test is Critical
The bend test is mandatory for piling pipes and directly assesses the weld's ductility under bending stresses similar to those during installation
4. Corrosion Protection
For permanent structures, specify appropriate coatings based on environmental conditions:
FBE/3LPE: For buried piles and harsh environments
Coal Tar Epoxy: For marine applications
Galvanized: For above-ground applications
5. End Finishes
Plain ends (PE) – standard for field butt-welding
Beveled ends (BE) – for field welding (30° bevel)
Driving shoes/pile tips – optional for hard driving conditions
6. Supplementary Requirements
ASTM A252 includes optional supplementary requirements that can be specified for critical applications :
S1: Charpy V-Notch Impact Test (for low-temperature applications)
S2: Drop-Weight Test (fracture toughness verification)
7. Third-Party Inspection
Available inspection services include SGS, BV, Lloyds
Summary
ASTM A252 Grade 1 Spiral Submerged Arc Welded (SSAW) steel pipe is the entry-level specification for large-diameter steel pipe piles used in foundation construction. With minimum yield strength of 30,000 psi (205 MPa) and tensile strength of 50,000 psi (345 MPa), Grade 1 is the most economical option, suitable for light-load applications, good soil conditions, and temporary structures .
Key features:
Material standard: ASTM A252 Grade 1 – entry-level strength grade for piling
Yield strength: 205 MPa (30,000 psi) minimum – baseline for A252 grades
Elongation: 30% minimum – good ductility for installation
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
Bend test mandatory – critical for piling applications
No hydrostatic test required – pipes are filled with concrete, not used for fluid conveyance
Most economical choice among ASTM A252 grades
Common applications include:
Light structural foundations for residential/commercial buildings
Temporary shoring and excavation support
Shallow piling in good soil conditions
Small bridges and light-duty marine structures
When ordering, specify: ASTM A252 Grade 1, SSAW (Spiral Submerged Arc Welded), Size (OD x WT), Length, End Finish (plain/beveled), Coating Requirements (if needed), and Mill Test Certificate to EN 10204 Type 3.1B. For most general foundation applications requiring higher strength, Grade 2 is the more common and recommended grade .
