Q:Which steel pipe is best for piling foundations?

The long-term stability of any major bridge, port facility, or high-rise building rests entirely on the strength and integrity of its foundation. In modern construction, steel pipe piles are a proven, high-capacity solution for these deep foundations, but a frequent and critical question we address is which type of pipe is best suited for the job.

From an engineering standpoint, making the right choice is key to ensuring a foundation that is both safe and cost-effective. This guide will walk you through the primary options and the factors you should consider.

The Governing Standard for Piling: ASTM A252

Before discussing specific pipe types, it’s essential to establish the governing standard. For piling applications in North America and many international projects, that standard is overwhelmingly ASTM A252.

As we’ve covered previously, this specification is written exclusively for steel pipe intended for use as a structural, load-bearing element. Any pipe selected for a piling project, whether LSAW or SSAW, should be specified to meet or exceed the requirements of ASTM A252, typically Grade 2 (35 ksi yield) or Grade 3 (45 ksi yield).

Evaluating the Primary Options: SSAW vs. LSAW

Both SSAW (Spiral Weld) and LSAW (Longitudinal Weld) pipes are widely and successfully used for piling. The best choice depends on your project’s specific geotechnical conditions, structural loads, and budget.

SSAW (Spiral SAW) Pipe Piles: The Industry Workhorse

For a significant number of piling projects, SSAW pipe is the preferred choice, and for good reason.

• Key Advantage – Cost-Effectiveness: The continuous, efficient manufacturing process of SSAW pipe often makes it the most economical option, particularly for projects requiring large quantities of piling.
• Performance: SSAW pipe provides excellent structural capacity and is perfectly suited for most foundation designs where the pipe is driven to a specific depth and often filled with concrete. The spiral nature of its weld can also contribute to the pipe’s overall rigidity.
• Ideal Use Cases: SSAW pipe piles are an outstanding solution for a wide range of applications, including building and warehouse foundations, trestle bridges, retaining walls, and communication towers.

LSAW (Longitudinal SAW) Pipe Piles: The Heavy-Duty Solution

When project demands become more extreme, LSAW pipe piles offer an additional level of performance and security.

• Key Advantage – Heavy-Wall Capability: The JCOE manufacturing process allows LSAW pipes to be produced with extremely heavy wall thicknesses. This makes them exceptionally resistant to damage and buckling during driving in very hard or obstructed ground conditions.
• Performance: The use of single, high-quality steel plates ensures very uniform mechanical properties throughout the pipe, which is a benefit in designs with high, concentrated loads.
• Ideal Use Cases: LSAW pipe piles are the necessary choice for the most demanding projects, such as foundations for major long-span bridges, deepwater marine terminals, and offshore wind turbine jackets where piles are subjected to extreme axial, lateral, and dynamic loads.

Key Selection Factors for Your Project

Our technical specialists typically advise clients to consider these three factors:

1. Geotechnical Conditions: Are you driving into soft clays or dense glacial till with boulders? Harsher driving conditions favor the robustness of a heavy-wall LSAW pipe.
2. Structural Loads: What are the final design loads the foundation must support? Exceptionally high compressive or lateral loads may necessitate the heavy-wall capabilities of LSAW.
3. Project Economics: Is this a standard foundation design in moderate soil conditions? If so, the high performance and cost-effectiveness of SSAW pipe make it a very compelling choice.

The Allland Steel Recommendation

Our guidance is to view SSAW pipe piles as the highly capable and economical baseline for the majority of foundation projects. For projects involving exceptional design loads, heavy-wall requirements, or particularly challenging driving conditions, upgrading to LSAW pipe piles provides a superior margin of safety and performance.

The optimal foundation solution depends on a thorough analysis of your project’s geotechnical report and structural design. The specialists at Allland Steel are experienced in supplying both LSAW and SSAW pipe piles for major infrastructure projects worldwide and can help you make the most effective material choice.

Contact a piling specialist at Allland Steel to review your project’s foundation requirements.