ASTM A252 Grade 3 Double-Sided Submerged Arc Welding (DSAW) Steel Pipe
Basic Overview
ASTM A252 Grade 3 DSAW (Double-Sided Submerged Arc Welded) steel pipe is the highest strength grade in the ASTM A252 specification for steel pipe piles, designed for the most demanding foundation applications [citation:6, citation:9]. With minimum yield strength of 45,000 psi (310 MPa) – approximately 50% higher than Grade 1 and 28% higher than Grade 2 – Grade 3 is the premium choice for heavy-load projects such as high-rise buildings, large bridges, offshore platforms, and seismic zones [citation:4, citation:10].
DSAW is a specific manufacturing process where the welding arc is submerged in granular flux, and both inside and outside welds are applied-usually in separate processes-with these welds consuming a portion of each other to form a single, high-quality weld nugget . This process is particularly well-suited for large-diameter, thick-wall pipes required for heavy-load piling applications.
Name Explanation
| Part | Meaning |
|---|---|
| ASTM | ASTM International (American Society for Testing and Materials) |
| A252 | Standard specification for welded and seamless steel pipe piles |
| Grade 3 | The highest strength grade, with minimum yield strength of 45,000 psi (310 MPa) [citation:4, citation:9] |
| DSAW | Double-Sided Submerged Arc Welding – both inside and outside welds are required; the weld arc is submerged in flux during welding |
Key Features of DSAW Manufacturing for Grade 3
| Feature | Description |
|---|---|
| Welding Process | The welding arc burns under a flux layer, melting the welding wire and the edge of the tube blank; double-sided welding ensures full penetration . The separate welds consume a portion of the other, resulting in a single high-quality weld nugget . |
| Key Parameters | Current: 400–800A; Voltage: 28–35V; Speed: 20–50 m/h |
| Filler Materials | Welding wire: H08A (special for low carbon steel); Flux: HJ431 (anti-oxidation, stable arc) |
| Auxiliary Process | Gas shielded welding (CO₂ flow rate 10–25 L/min) for local repair; Manual arc welding with preheating 100–150°C for small-diameter or on-site repair |
| Forming Methods | Two primary methods: UOE (U-ing, O-ing, and Expanding) or JCO/JCOE (progressive J-C-O forming) |
| Cold Expansion | Pipe may be expanded up to 1.5% to achieve final OD; this process can increase yield strength |
| Raw Material | Flat steel plates (not coils), allowing for thicker walls and larger diameters |
| Typical Size Range | 12" to 64" OD (304.8 mm to 1625.6 mm); up to 84" (2134 mm) available [citation:4, citation:7] |
| Wall Thickness | 0.109" to 2.5" (2.77 mm to 63.5 mm); common range 6–40 mm [citation:4, citation:6] |
| Length | 6 m to 32 m standard; custom lengths up to 70 m available [citation:8, citation:9] |
Chemical Composition
ASTM A252 specifies only maximum limits for phosphorus and sulfur. All three grades share the same composition limits; the distinction is based on mechanical properties [citation:4, citation:8, citation:9]:
| Element | Maximum % | Notes |
|---|---|---|
| Carbon (C) | 0.26% | Provides basic strength [citation:4, citation:9] |
| Manganese (Mn) | 1.35-1.60% | Enhances strength [citation:4, citation:9] |
| Silicon (Si) | 0.45% | Deoxidizer [citation:8, citation:9] |
| Phosphorus (P) | 0.050% | Mandatory maximum limit [citation:4, citation:8, citation:9] |
| Sulfur (S) | 0.030-0.045% | Controlled for weldability [citation:8, citation:9] |
Note: The steel shall contain no more than 0.050% phosphorus . Although chemical composition is not mandatory, the manufacturer is required to provide a smelting analysis report to ensure weldability .
Mechanical Properties
| Grade | Yield Strength (min) | Tensile Strength (min) | Elongation (min) | Strength vs. Grade 1 |
|---|---|---|---|---|
| Grade 1 | 205 MPa (30,000 psi) [citation:4, citation:9] | 345 MPa (50,000 psi) [citation:4, citation:9] | 30% [citation:4, citation:9] | Baseline |
| Grade 2 | 240 MPa (35,000 psi) [citation:4, citation:9] | 415 MPa (60,000 psi) [citation:4, citation:9] | 25% [citation:4, citation:9] | +17% yield |
| Grade 3 | 310 MPa (45,000 psi) [citation:4, citation:9, citation:10] | 455-456 MPa (66,000 psi) [citation:4, citation:9, citation:10] | 20% [citation:4, citation:9] | +51% yield |
*Grade 3 is the premium choice for heavy-load applications, offering superior mechanical properties significantly better than the other two grades [citation:9, citation:10].*
Dimensional Tolerances
| Parameter | Tolerance |
|---|---|
| Outside Diameter | ±1% of specified OD |
| Wall Thickness | Not more than 12.5% under nominal |
| Weight | +15% / -5% of theoretical weight |
| Length | +100mm / -0mm typical |
Size Availability:
OD Range: 6" to 56" (168.3 mm to 1422 mm); up to 84" (2134 mm) available [citation:7, citation:9]
Wall Thickness: 0.134" to 2.5" (3.40 mm to 63.5 mm); typical DSAW range 6–40 mm [citation:4, citation:6, citation:9]
DSAW vs. Other Manufacturing Methods for A252 Grade 3
| Aspect | DSAW (Double-Sided SAW) | LSAW (Longitudinal SAW) | ERW | SSAW (Spiral SAW) |
|---|---|---|---|---|
| Weld Seam | Single longitudinal, welded both sides | Single longitudinal seam | Single longitudinal seam (no filler) | Continuous spiral seam |
| Diameter Range | 12" to 64"+ | 12" to 64" | Up to 24" | 8" to 120"+ |
| Wall Thickness | Up to 2.5" (63.5 mm) | Up to 2.5" (63.5 mm) | Moderate | Up to 1.0" (25.4 mm) |
| Raw Material | Flat steel plate | Flat steel plate | Steel coil | Steel coil |
| Weld Inspection | 100% ultrasonic continuous automatic flaw detection [citation:2, citation:4] | 100% ultrasonic | Standard | Standard |
| Typical Application | Large-diameter heavy-load piling | Large-diameter piling | Smaller diameter piling | Very large diameter piling |
Testing & Inspection Requirements
| Test Type | Requirement | Notes |
|---|---|---|
| Chemical Analysis | Per heat lot | Phosphorus and sulfur limits enforced |
| Tensile Test | Per lot | Verifies yield and tensile strength |
| Flattening Test | Required | Checks ductility and weld integrity |
| Hydrostatic Test | Each pipe | Pressure integrity verification |
| Ultrasonic Inspection | 100% of weld seam | Continuous automatic flaw detection; ensures no unfused or cracked parts [citation:2, citation:4] |
| X-ray Inspection | When specified | For critical applications |
| Visual Inspection | 100% | Surface condition, weld appearance |
| Dimensional Inspection | 100% | Per ASTM A252 tolerances |
Weld Quality Control Requirements :
Groove treatment: Remove oil and rust within 20mm on both sides of the groove to reveal metallic luster
Elongation guarantee: Strictly control interlayer temperature; elongation should be ≥20% when wall thickness ≥7.9mm
Applications
Grade 3 is the premium choice for the most demanding foundation applications [citation:6, citation:10]:
| Application | Description |
|---|---|
| High-Rise Buildings (>50 stories) | Deep foundations for skyscrapers; core tube pile foundations requiring maximum load capacity [citation:6, citation:10] |
| Large Bridges | Main pier pile foundations for cross-river/sea bridges; cross-sea bridge piers |
| Offshore Platforms | Marine structures requiring high strength-to-weight ratio and corrosion resistance |
| Seismic Zones | Structures requiring enhanced energy absorption and ductility |
| Heavy Industrial Foundations | Equipment foundations requiring maximum load capacity |
| Extreme Soil Conditions | Very soft or unstable soils requiring maximum bearing capacity |
| Permanent Load-Bearing Structures | As permanent load-carrying members or as shells for cast-in-place concrete piles [citation:6, citation:10] |
Key Advantages
| Advantage | Description |
|---|---|
| Highest Strength | 45,000 psi yield – 51% higher than Grade 1, 28% higher than Grade 2 [citation:4, citation:9] |
| Superior Weld Integrity | Double-sided welding with 100% ultrasonic inspection ensures robust, reliable seams [citation:2, citation:4] |
| Large Diameter Capability | DSAW produces pipes from 12" to 64" OD – ideal for large-diameter heavy-load piling |
| Thick Walls | Suitable for heavy-load applications requiring substantial wall thickness (up to 2.5") |
| Full Penetration Welding | Double-sided submerged arc welding ensures complete penetration and eliminates defects |
| High Structural Integrity | Optimized for axial pressure bearing capacity and bending resistance |
| Composite Structure Capability | Often filled with grouting concrete to form steel tube concrete composite structure, significantly improving bearing capacity and seismic performance |
| Corrosion Protection Options | FBE, 3LPE, coal tar epoxy, galvanizing, bituminous coating available [citation:1, citation:3] |
Important Considerations
1. Grade 3 vs. Lower Grades
Grade 1: Light-load applications, good soil conditions, temporary structures
Grade 2: Most common grade – medium-rise buildings, general piling
Grade 3: Premium grade – heavy-load applications, deep foundations, marine structures, seismic zones [citation:6, citation:10]
2. Weld Quality Requirements for Grade 3
100% ultrasonic inspection of weld seam is mandatory
Preheating 100–150°C required for manual arc welding
Strict control of interlayer temperature to ensure elongation ≥20%
Groove preparation: remove oil and rust within 20mm of groove to reveal metallic luster
3. Hydrostatic Testing
ASTM A252 requires hydrostatic testing for all pipe piles
This ensures pressure integrity before installation
4. End Finishes
Plain ends: Standard for most applications
Beveled ends: For field welding, 30–35° bevel angle
Driving shoes/pile tips: Optional for hard driving conditions
5. Coating Options
Black (bare): Standard mill finish
FBE (Fusion Bonded Epoxy): Corrosion protection
3LPE (3-layer polyethylene): Buried applications
Coal Tar Epoxy: Marine environments
Galvanized: Outdoor applications
Varnish/Anti-rust oil: Temporary protection
6. Complementary Specifications
ASTM A252 Grade 3 pipe piles can also be manufactured using:
Seamless (SMLS): For smaller diameters
LSAW (Longitudinal Submerged Arc Welded): For large-diameter thick-wall pipes
EFW (Electro-Fusion Welded): For specific applications
7. Mill Test Certificate
Typically provided as EN 10204 Type 3.1B with full test results
Third-party inspection (SGS, BV, Lloyds) available upon request [citation:3, citation:7]
Summary
ASTM A252 Grade 3 Double-Sided Submerged Arc Welded (DSAW) steel pipe is the premium, highest strength specification for steel pipe piles in foundation construction [citation:6, citation:9]. With minimum yield strength of 45,000 psi (310 MPa) – 51% higher than Grade 1 and 28% higher than Grade 2 – and tensile strength of 66,000 psi (455 MPa), Grade 3 is the ultimate choice for heavy-load applications requiring maximum structural integrity [citation:4, citation:9].
Key features of DSAW manufacturing:
Produces pipes from 12" to 64" OD with wall thickness up to 2.5" (63.5 mm)
Double-sided welding (inside and outside) creates a single high-quality weld nugget with full penetration
Formed from flat steel plates using UOE or JCO forming methods
100% ultrasonic inspection of weld seam ensures no unfused or cracked parts
Cold expansion up to 1.5% achieves final dimensions and may increase yield strength
Suitable for steel tube concrete composite structures, significantly improving bearing capacity and seismic performance
Common applications include:
High-rise building foundations (skyscrapers) [citation:6, citation:10]
Large bridge piers and cross-sea bridges
Offshore platforms and marine structures
Seismic zones requiring enhanced energy absorption
Heavy industrial foundations
Extreme soil conditions requiring maximum bearing capacity
When ordering, specify: ASTM A252 Grade 3, DSAW (double-sided submerged arc welded), Size (OD x WT), Length, End Finish (plain/beveled), and Coating Requirements. Grade 3 is the recommended choice for heavy-load, deep foundation projects requiring maximum strength and structural integrity [citation:6, citation:10].
