O-Pile® systems are a rapidly expanding construction method that utilize pipes to form extremely strong foundations, barriers and retaining walls in a cost-effective way.

O-Pile® systems are steel pipes with welded connectors that form a continuous or combined steel wall. Recently, there has been a huge increase in the use of O-Pile® systems on construction projects around the world, particularly with ports, retaining walls, and deep foundations, as well as on a variety of other large- and small-scale projects. The reason is simple: O-Pile® systems offer a stronger, more cost-effective alternative to both traditional concrete barrier walls and solely U- or Z-shaped sheet piling.

There are three key technical reasons why engineers and designers often consider the O-Pile® system more preferable than other sheet pile or concrete options:

1. O-Pile® systems, because of their excellent load bearing geometry, often display a much better strength-to-weight ratio and have impressive section modulus values that are better able to resist high bending moments.
2. The surcharge capacity of O-Pile® systems is usually significantly higher than U- or Z-shaped and combined sheet piles, thus allowing O-Pile® systems to sustain greater vertical forces.
3. The interlock capacity of O-Pile® systems is incredibly strong and has been tested to more than 19 kips/in or 3400 kN/m.

O-Pile® systems are just plain stronger, any way you look at it.

O-Pile® systems connected together with patented connectors form extremely effective and strong retaining walls for projects such as port and highway constructions. They can also effectively transfer loads from structures such as parking garages (or any similar-scale construction project) to stronger soil layers deeper underground.

There are only a handful of countries in the world where Flat, Z- and U-shaped steel piles are manufactured, whereas pipe factories are abundant worldwide. Therefore, a construction project using O-Pile® systems will almost always utilize over 75% locally produced pipe thereby avoiding the arbitrary expense of costly importation fees. Either new or used steel pipes are abundant, cheap and easy to manufacture, so they offer a much more economical solution for large-scale construction projects when compared to traditional concrete or steel sheet pile alternatives.

WOM-XL / WOF-XL

O-Pile is made possible by the patented WOM-XL/WOF-XL weld-on connector series.

With O-Pile® WOM-XL and WOF-XL interlock connectors, the design engineer is able to utilize readily available, locally produced pipes to provide practical, cost-effective solutions that exceed project requirements.

Weld guidelines for connectors:

• All seams should be at least 6 mm (~.236”).
• Both sides have a tip and toe welding continuously of 500 mm (~20.0”).
• Both sides are tack welded in the free length between tip and toe welding with 200 mm/m (~8”/3.28’). The distance from seam to seam is 800 mm (~31.5”) or less.
• In salt water the water side is continuously welded on the whole pile length. Rear side is as above in step #3.

Note: the above is for references purposes only and the welding design must be checked against other considerations such as anchor forces, shear forces and otherwise difficult driving conditions.

Example products

¹ G _y – weight
² W _y – section modulus
³ J _y – moment of inertia
⁴ b – panel width
⁵ OD – pipe outer-diameter
⁶ t – pipe thickness

Case Study: Hatem Bridge

WOM/WOF-XL connectors were used to form high capacity pipe to pipe cofferdams at the Hatem Memorial Bridge foundation strengthening project in North-East Maryland.

The high bending strength and stiffness of a continuous pipe-to-pipe wall was preferred over other options to resist over 90 feet of water pressure and form a safe excavation for the contractor.

WOM/WOF-XL connectors provided the highest degree of tension and bending strength available to secure the pipe-to-pipe connection and ensure pile integrity after hard driving.

The pipe-to-pipe solution is quickly gaining recognition as the most efficient high capacity solution for retaining structures in the marketplace today. The growing use of pipe-to-pipe solutions has been made feasible by the introduction of the WOM/WOF-XL connector. Previous methods of connecting pipes were complex, slow and difficult to get right. WOM/F-XL gives the contractor for the first time a high capacity connection that’s easy to install.

Other Projects Using The High Capacity O-Pile System

Strength vs. Weight

When comparing sheet-piling panel solutions across the spectrum of types, brands, configurations, and options, a general trend becomes clear: stronger panels weigh more.

This fact is illustrated in figure 1, section-modulus vs. weight, and a rough linear relationship become clear.

Efficiency Zones

The standard efficiency zone can be seen in figure 2. Even with the variety available with standard panel types, the roughly linear relationship remains.

Figure 1: typical panel efficiencies	Figure 2: efficiency zones

The Power of the Circle

Now, if we graph a selection of O-Pile systems (figure 3), we see something dramatically different: we begin to see an exponential function where strength goes up radically without the familiar increase in panel weight. And we see an entirely new efficiency zone, with a drastically wider range of applications.

Figure 3: O-Pile systems zone	Figure 4: O-Pile systems Power Curve

We call this the O-Pile Power Curve: an exponential increase in section modulus with only modest increase in panel weight. As you can see in figure 4, the strength:weight ratio becomes almost vertical. This is the power of the circle.

How Does it Work?

Section modulus is largely a function of diameter, while weight is mainly a function of pipe thickness. Varying these two basic properties of the O-Pile® system thus allows for ideal efficiency by choosing among a vastly more efficient range of solutions.

Driving O-Pile® system

O-Pile® system are much easier to drive than is often thought. Usually, strict noise abatement standards can be easily met even for urban settings.

Vibratory hammers, impact diesel hammers and even press-in methods have been used all over the world. Driving obstacles can often be removed from inside the pipes by excavation, drilling, or jetting, without disturbing the environment.

Simply put, O-Pile® system can be driven quietly and effectively with a wide range of equipment.

O-Pile® system can be easily spliced, due to small production tolerances.

Waterproofing O-Pile®

If your O-Pile® project involves cofferdams, dewatering, tunnels, cutoff walls for site remediation, or any application where water leakage presents a challenge, then sealed O-Pile® system are an excellent solution. WADIT®, a globally proven sheet piling interlock sealant, is highly effective in O-Pile® interlocks and can meet the most challenging waterproofing needs.

WADIT® can be used in every possible environment (from tropical to arctic) and is particularly effective in marine conditions.

WADIT® sealant, used in conjunction with O- Pile® pipes and connectors, is increasingly the “go-to” solution for engineers and designers looking for an effective waterproofing option in terms of strength, price, safety and convenience.

O-Pile® and Corrosion

Because such a large number of construction projects using O-Pile® system are situated in marine environments, one of the most common questions is: how well do O-Pile® system stand up to corrosion?

Along with their enormous strength-to-weight ratio and overall cost-effectiveness, O-Pile® system have a distinct advantage over traditional steel sheet piles: O-Pile® system save costs with easier application of corrosion protection compared to other geometries, and by having a minimized exposed surface. Furthermore, the interior of the pipe can be sealed off (capped or filled) from oxygen infiltration in order to avoid inside corrosion.

Also, concrete can be poured inside the O-Pile® itself, thus further increasing strength while also preventing oxidization or corrosion on the interior surface, so O-Pile® system have only the exterior face exposed to corrosion. This is in contrast to a traditional steel beam, which has all of its surface faces exposed to corrosive elements.

Contact

Email: info@o-pile.com

O-Pile
PO Box 684361
Austin, TX 78768

Tel: +1 512-243-1448

We are actively looking for local representatives in many global markets, if you are a pipe producer/supplier or in the sheet piling distribution business please let us know if you may be interested in becoming part of our O-Pile global network.