What is the proper vinyl sheet pile driving method for different soil types?

“Pitch and drive” method is the most practical way of pile driving in loose soils especially when using short piles. Also called “set and drive”, this method installs piles one by one. However, with only one interlock in control, sheet piles have high tendencies of rotating from the axis and leaning forward or backward. Panel driving is recommended for the dense deposit of sands and compact cohesive soils such as heavy clay or in presence of obstructions. In this method, a number of piles are interlocked together before driving. The panel of piles is supported by guide frames and driven gradually in sequence, sometimes in a staggered manner. The method can achieve installations of longer piles in more difficult ground conditions with better results in sheet pile alignment and verticality. In cases of difficult ground conditions such as hard strata and the presence of obstructions, driving assistance is employed along with a proper selection of driving method and equipment. Jetting and drilling help by loosening or eliminating obstructions by creating pressure right under the tip of the sheet pile being driven. Long and slender PVC sheet piles require steel mandrels as supports when driven in such conditions. Mandrel, which shape is similar to sheet pile profiles, increases the rigidity of Plastic Sheet Pile and supports the weight of the driving equipment such as a vibro-hammer.

What is the proper machine to drive piles in different conditions?

Impact driving is suitable for all soil types but appears to create the highest degree of stress to sheet piles. It is more appropriate to cohesive soils and soft soils such as silts and peats, loose medium to coarse sand, and gravels free of rock inclusions. Drop hammers such as the hydraulic hammer are the common types of impact-driving machinery. Driving using vibratory hammers is ideal for non-cohesive or granular soils such as soft soils and round-grained sand or gravel. It has also shown satisfactory performance in sandy, silty, or softer clay soils. It is less effective in angular-grained materials and soils with a firm consistency. With the introduction of vibration, however, the sub-soil can be further compacted, increasing penetration resistance and ultimately-refusal. If this is the case, driving aids like jetting and drilling might be necessary.

What are the pvc sheet pile selection criteria for soil condition of different hardness?

General rule of the thumb: “the harder the soil, the stronger and stiffer sheet pile section should be used”. Driveability of a pile section is a consequence of its cross-sectional properties (thickness, depth, and width), designed shape, length, grade, and the applied load. Hardness of soil strata characterized by SPT or CPT values is used to predict soil resistance which is essential in the calculation of driving force to be applied. Knowing the range of force from the selected driving machine, corresponding sheet pile sections can be picked according to their yield strength and elastic modulus.

How should I choose a sheet pile section for soils with, say, SPT Value, N=30? Can I still consider using vinyl or shift to steel?

Every sheet pile material has a design purpose, strengths, and areas of improvement. The availability of different materials denotes the need for a special material for a specific application. Plastic or synthetic sheet piles for example are known for being light and corrosion-resistant; Steel sheet piles are recognized for their extraordinary strength and versatility; and so on.

May 6, 20203 min read

Brief Description and Comparisons of LSAW, SSAW, and ERW Pipes

Updated: Nov 11, 2023

High quality steel pipes are produced from three (3) manufacturing processes: Seamless, LSAW (longitudinal-seam submerged arc welding), and ERW (electric resistance welding). LSAW and ERW pipes are highly regarded for their numerous fields of application. They are tremendously used in foundation solutions and systems, marine construction, structural construction, and diverse applications in water projects, petrochemical, chemical, and power industry, agricultural irrigation, urban construction, and more.

LSAW Pipes has two types: Longitudinal (Single or Double Straight-seam Weld, DSAW) and Spiral (also called SSAW, HSAW, or SAWL). What makes DSAW pipes differ from other LSAW pipes is that DSAW have a seam weld in the inside and outside of the pipe, while the latter have a single seam weld on the outer surface, longitudinal or cross sectional.

SSAW and LSAW pipes employ a common manufacturing procedure called “JCOE and UOE forming process”. The difference is SSAW pipes are welded in the helix or spiral position while LSAW pipes are welded in the longitudinal direction.

SSAW pipe takes form by rolling and welding a steel strip in a way that the pivotal direction is oblique to the axis or pipe center, making the weld seam in a spiral line. LSAW pipes are produced by molding steel sheets to a cylinder and joining the ends together by welding in a straight line.

The LSAW pipe diameter range is normally from 16 inch to 60 inch (406mm to 1500mm). They have good performances on high pressure resistance, and low-temperature corrosion resistance.

ESC Steel however can supply pipes between 1 inch to 167 inch (21mm up to 4267mm) in diameter and thicknesses between 3/32 inch to 4 inch (2.1mm up to 100mm). Largest diameters and thickness of ESC Steel Pipes are manufactured using LSAW which are highly recommended for load bearing piles, combination wall piles and other applications. In the oil and gas industry, large-diameter API 5L LSAW pipes are use d to transport hydrocarbons over long distances efficiently.

HSAW (helical submerged arc welding) or SSAW pipe diameter range is generally 20 inch to 100 inch (406mm to 2540mm). One advantage of SSAW is the possibility to obtain different diameter

of SSAW pipes from a standard size of steel strip without cutting. On the other hand, spiral welding seam length is quite longer than the pipe length, making it more costly and prone to cracks, air holes, cinder inclusion, partial welding, and more.

HSAW or spiral weld pipes are used for non-critical applications such as water distribution and not for oil & gas. ESC recommends SSAW pipes as King Piles for our Combination Walls and also as Dredging Pipe.

Overall, it appears that LSAW Pipes has slight edge over SSAW Pipes. Below points explains it why.

SSAW Pipes has greater residual stress than LSAW pipes. LSAW pipes passes through uniform expansion process.
SSAW pipes weld stress concentration phenomenon is considered serious by category. The heat affected zone of SSAW pipes is larger than LSAW pipes. Heat affected zones are considered weak points where failure might start.
Geometry accuracy of LSAW pipes is better than SSAW pipes, a key in the ease of installation.
The welding line of LSAW pipe is around 60% lesser than of SSAW pipes.
Using steel plates, quality of LSAW pipe can be tested by non-destructive procedures. While SSAW pipes using hot-rolled coils should be tested with destructive methods such as x-ray.
LSAW pipes adopt welding after molding process where various checks can take place. SSAW pipes employ molding and welding at the same time, pre-checks are not being carried out.

ESC Steel LLC’s wide range of steel pipes also includes ERW pipes. ERW pipes are manufactured using steel coils: the coil is first uncoiled, smoothed, cut, and finally formed into a pipe shape by joining its two extremities by high-frequency electrical welding (HFI & HFW). ERW pipes are available in sizes between ½ inch and 20 inches (12mm to 508mm) and rapidly becoming a popular alternative to seamless pipes, both in terms of price and performance.

Do you need professional assistance in your project? Please don’t hesitate to contact us at (281) 205 7261 (Houston Office) (704) 654 0321 7261 (North Carolina Office) email at info@escsteel.com

Brief Description and Comparisons of LSAW, SSAW, and ERW Pipes

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