Steel Pipe Pile Manufacturing Methods Explained

You are designing a deep foundation for a bridge or a port. The engineer specifies steel pipe piles. But how are they made, and which manufacturing method is right for your project?

Steel pipe piles are manufactured using three main methods: seamless (no weld), longitudinal welded (LSAW¹), and spiral welded (SSAW²). Each method has different characteristics for diameter, wall thickness, weld integrity, and cost. LSAW¹ pipes offer the best quality for critical piling applications.

I have supplied steel pipe piles for projects across the Middle East and Southeast Asia. A port project in the UAE used LSAW¹ piles for the main berth. A bridge project in Southeast Asia used SSAW² piles for the approach trestle. Let me walk you through the manufacturing methods.

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What is the difference between seamless and welded steel pipes?

The main difference between seamless and welded steel pipes is the presence of a weld seam. Seamless pipes have no weld, while welded pipes¹ have a longitudinal or spiral seam.

Seamless pipes are made by piercing a solid steel billet and rolling it into a tube. Welded pipes are made by forming steel plates or coils into a cylinder and welding the seam. Seamless pipes have uniform properties and no weld to fail, but they are limited in diameter and more expensive. Welded pipes can be made in larger diameters and longer lengths at lower cost².

Detailed Comparison of Seamless and Welded Pipes

Let me explain the differences in detail.

Seamless Steel Pipes

Property	Range
Diameter	Up to 24 inches (610 mm)
Wall thickness	Up to 40 mm
Length	Typically 10-12 m
Weld seam	None
Manufacturing	Pierced billet, rolled
Strength	Excellent (uniform properties)
Cost	Highest

Advantages of Seamless Pipes

• No weld seam to fail during driving
• Uniform mechanical properties around the pipe
• Excellent fatigue resistance
• No risk of weld defects

Disadvantages of Seamless Pipes

• Limited diameter (typically under 24 inches)
• Higher cost² than welded pipes¹
• Longer lead times for large diameters

Welded Steel Pipes (LSAW and SSAW)

Property	Range
Diameter	16 to 120 inches (406 to 3,048 mm)
Wall thickness	4 to 50 mm+
Length	12-64 m
Weld seam	Longitudinal or spiral
Manufacturing	Formed plates or coils, welded
Strength	Good (weld is the critical point)
Cost	Lower than seamless

Advantages of Welded Pipes

• Larger diameters available
• Longer lengths reduce field splices
• Lower cost² than seamless
• Wall thickness can be varied

Disadvantages of Welded Pipes

• Weld seam is a potential weak point
• Requires inspection of welds
• Weld properties differ from base metal

My Experience
For a high-load bridge foundation, we used seamless pipe piles. The uniform properties and absence of a weld seam gave the engineer confidence in the design. However, the cost² was 40% higher than welded alternatives. For most piling projects, welded pipes¹ are the better choice.

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How are LSAW pipes manufactured?

LSAW (Longitudinal Submerged Arc Welded¹) pipes are made from steel plates formed into a cylinder with a single straight weld seam. They are the preferred choice for critical piling applications.

LSAW pipes start as steel plates. The plate is cut to the required width and then formed into a cylinder using a UOE, JCOE, or press bending process. The formed cylinder has a single longitudinal seam. This seam is welded from both the inside and outside using submerged arc welding (DSAW). After welding, the pipe is often mechanically expanded to achieve precise dimensions and reduce residual stresses.

Step-by-Step LSAW Manufacturing Process

Let me walk you through the LSAW manufacturing process.

Step 1: Plate Preparation
Steel plates are inspected for surface defects and dimensions. The edges are beveled to prepare for welding. The plates are cut to the exact width required for the pipe diameter.

Step 2: Forming (UOE Process)
The UOE process² has three stages:

• U-ing: The plate is pressed into a U shape using a U-press
• O-ing: The U shape is pressed into an O shape using an O-press
• Expanding: The pipe is mechanically expanded to achieve precise diameter and reduce residual stresses

Alternative forming methods include JCOE (J-ing, C-ing, O-ing, Expanding) for thicker walls.

Step 3: Welding (DSAW)
Double Submerged Arc Welding³ is used:

• Inside weld: First pass from inside the pipe
• Outside weld: Second pass from outside
• The weld is fully penetrated through the wall thickness
• Submerged arc process uses granular flux to protect the weld

Step 4: Inspection
The weld is inspected using:

• Visual inspection of weld profile
• Ultrasonic testing (UT) for internal defects
• Radiographic testing (RT) for critical applications

Step 5: Finishing

• Pipe ends are beveled for field welding
• Hydrostatic testing for pressure applications (if required)
• Coating application (if specified)

LSAW Pipe Characteristics

Property	Range
Diameter	16 to 60 inches (406 to 1,524 mm)
Wall thickness	6 to 50 mm+
Length	12-18 m typical
Weld seam	One longitudinal seam
Quality	Excellent (DSAW full penetration)
Cost	High

My Experience
For a deepwater port project, we used LSAW pipes with 30 mm wall thickness. The UOE forming produced pipes with perfect roundness. The DSAW welds passed ultrasonic inspection with no defects. The piles were driven to 40 m depth through dense sand.

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What are the advantages of SSAW pipes?

SSAW (Spiral Submerged Arc Welded) pipes offer several advantages for piling applications, especially for large diameters and long lengths.

SSAW pipes are manufactured by forming steel coil into a spiral and welding the seam using submerged arc welding. The main advantages are large diameters (up to 120 inches), very long lengths (up to 64 m), and lower cost than LSAW. They are ideal for projects where large diameter piles are needed and driving conditions are moderate.

Advantages of SSAW Pipes

Let me explain the key advantages of SSAW pipes for piling.

1. Large Diameters¹
SSAW pipes can be manufactured in diameters up to 120 inches (3,048 mm) or more. This makes them ideal for large-diameter pipe piles used in marine structures and deep foundations where LSAW pipes would require very wide plates.

2. Very Long Lengths²
Because the manufacturing process is continuous, SSAW pipes can be produced in lengths up to 64 meters. This reduces the number of field splices needed, saving time and labor during installation.

3. Lower Cost³
SSAW pipes typically cost 20-30% less than LSAW pipes of the same diameter and wall thickness. The continuous manufacturing process is more efficient, and steel coils are often less expensive than steel plates.

4. Good for Moderate Driving Conditions⁴
For projects where driving conditions are not severe (soft to medium soils, no cobbles or boulders), SSAW pipes perform well and offer significant cost savings.

SSAW Pipe Characteristics

Property	Range
Diameter	16 to 120 inches (406 to 3,048 mm)
Wall thickness	4 to 25 mm typical
Length	Up to 64 m continuous
Weld seam	Helical (spiral)
Quality	Good
Cost	Lower than LSAW (20-30% savings)

When to Choose SSAW Pipes

Application	Suitable for SSAW?
Large diameter piles (>60")	Yes (often only option)
Long piles (over 30 m)	Yes (reduces splices)
Soft to medium soils	Yes
Hard driving with cobbles	No
Marine environment with corrosion allowance	Check wall thickness

My Experience
For a port approach trestle, we used SSAW pipes with 36-inch diameter and 12 mm wall thickness. The water depth was moderate (8 m), and the soil was soft sand. The SSAW pipes drove easily and cost 25% less than LSAW. The long lengths (50 m) eliminated field splices.

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How to choose the right pipe pile manufacturing method¹ for your project?

Choosing the right pipe pile manufacturing method¹ depends on project requirements for diameter, wall thickness, driving conditions², and budget³.

The selection guide considers: diameter needed⁴ (seamless for under 24", LSAW for 24-60", SSAW for over 60"), wall thickness (LSAW for thick walls over 25 mm), driving conditions² (LSAW for hard driving, SSAW for moderate), and budget³ (SSAW for cost savings, seamless for highest quality). For critical applications with hard driving, LSAW is the best choice.

Selection Criteria for Pipe Pile Manufacturing Methods

Let me provide a practical selection guide.

Selection by Diameter

Diameter Range	Recommended Method
Under 16 inches	Seamless or ERW
16-24 inches	Seamless, LSAW, or SSAW
24-60 inches	LSAW or SSAW
Over 60 inches	SSAW (only option)

Selection by Wall Thickness

Wall Thickness	Recommended Method
Under 12 mm	SSAW or LSAW
12-25 mm	LSAW or SSAW
25-40 mm	LSAW or seamless
Over 40 mm	LSAW (seamless limited to small diameters)

Selection by Driving Conditions

Driving Condition	Recommended Method
Soft soil, moderate driving	SSAW (most economical)
Dense sand, gravel	LSAW (stronger weld)
Cobbles, boulders	LSAW (thick wall)
Hard driving, impact hammer	LSAW (weld aligned with stress)
Sensitive, vibration limits	Any (depends on installation method)

Selection by Budget

Budget	Recommended Method
Lowest cost	SSAW
Moderate cost	LSAW
Highest quality (unlimited budget3)	Seamless

Decision Matrix

Project Requirement	Seamless	LSAW	SSAW
Small diameter (60")	Not possible	Limited	Best
Thick wall (>25 mm)	Limited	Best	Not possible
Hard driving	Best	Best	Not recommended
Cost sensitive	Not recommended	Good	Best
Long lengths (>30 m)	Not possible	Limited	Best

My Experience
For a major port project, we used LSAW for the main berth piles (30 mm wall, 24-inch diameter, hard driving) and SSAW for the approach trestle (12 mm wall, 36-inch diameter, moderate driving). Each method was chosen for its strengths. The LSAW piles cost more but handled the hard driving. The SSAW piles saved money where conditions were easier.

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Conclusion

Steel pipe piles are manufactured by three methods: seamless (no weld), LSAW¹ (longitudinal weld), and SSAW² (spiral weld). LSAW¹ offers the best quality for critical piling with thick walls. SSAW² is economical for large diameters and long lengths. Seamless is best for small diameters and highest loads.

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