Wide Applications of Steel Pipes

1. Steel Dredging Pipes

Many kilometers of steel dredge pipes have been used throughout the world in port dredging works and in mine dredging activities, particularly those involving the processing of mineral sands. Such pipes can be manufactured from AS: 1204-1972 steel plate or other more specialized steels which offer better abrasion resistant qualities combined with higher yield strength.

Both shore and floating line pipes are available in a wide range of sizes and thicknesses to suit requirements. In
the case of floating dredge pipelines, support pontoons are usually provided by steel mains. Steel mains are also used to manufacture wye pieces, bends and fabricated gate valves to suit the pipelines. The dredge pipes can be fitted with a variety of different joints including rubber slip-on sleeve joints, flanged joints, quick acting wedge lock couplings, and cast steel ball joints.

2. Steel Submarine Pipelines

Steel pipes are also extensively used as water, sewage, gas and oil transmission sub-marine lines. Other marine applications include sub-aqueous crossings and intake structures. The high strength, resilience, ductility and weldability of steel pipe makes it possible to assemble complete underwater sections with butt or lap welded joints then lower or pull the assembled sections into the underwater trench.

For lengthy subaqueous installations, pipe sections may be welded and lowered into the water in a continuous string from barges. Marine steel pipelines are provided with special outer protective coatings. It is often necessary to weight coat the outer surface of the pipe, or to provide suitably designed pre-cast concrete weights to overcome the buoyancy of the pipe particularly when empty, so as to secure it onto the sea or river bottom. This work can be undertaken by steel mains.

3. Aerial Crossings

The high beam strength of steel pipe makes it ideal for bridge and aerial crossings, as well as in pipe gallery installations. Supports can be installed further apart than with other materials, thus reducing overall cost and weight. In pipe galleries, long lengths can be installed, necessitating fewer joints that need support.

4. Steel Pipes for Structural Purposes

Welded steel pipes are widely used in a variety of load bearing structural components such as:

• Columns in factory buildings
• Falsework in bridge construction
• Wharf structures
• Support structures for industrial components
• Offshore drilling platform

In addition to being a sound structural material, steel piping also presents a clean and aesthetic appearance that is easy to clean and paint. For falsework in bridge construction and for offshore drill platforms, the employment of welded steel piping offers other advantages; the piping can be fabricated into sections on the shore line, the ends sealed, and the units floated into position for the final erection.

5. Special Berthing and Mooring Dolphin Piles

There is a growing need for this product on berthing and mooring dolphins at port and marine installations, thus the particular mention of this specific type of pile. Piles used for this purpose have achieved considerable significance in providing berthing accommodation for vessels of all types. Such piles are constructed from high elasticity steels capable of absorbing extremely violent ship impact loadings.

The piles are usually driven in specially designed groups with bracing systems or diaphragms designed to eliminate torsional effect in order to distribute blows from any direction equally to all piles, inducing them to bend simultaneously. The lower sections of these tubular piles and all sections, where the highest stress concentration is likely to occur, are constructed from steel with a high minimum yield strength such as DIN 17100 ST52-3, whilst from an economic viewpoint, the upper and also less stressed section can be constructed from steel conforming with DIN 17100 ST44-2. The design of the pile is important and it is usual for varying thickness sections to be employed in the pile manufacturing process to give the required elasticity and designed properties.

The pile thickness is heaviest at the bottom end; this thickness extends for some distance above the ocean or river bottom. The highest stresses are imposed on the pile in an area just below and just above the ocean or river bottom, where the pile receives impact from a berthing vessel. The pile usually then steps down in thickness in the higher regions to accommodate the reducing stresses in the higher portions of the pile. Please contact us for calculations of allowable axial compression loads, and the various diameters and thickness of steel pipes.

6. Welded Steel Pipe Piles For Bridges, Wharfs, Piers, Buildings and Other Structures

Solid and dependable foundations are built on welded steel piles. For many years leading contractors and engineers have used steel mains piles under bridges, buildings, wharves, piers and numerous other structures requiring firm dependable foundations. Given the advancement in the engineering practice, steel pipe piles provide construction designers with the necessary tools to assess future foundation problems.

Steel pipe piles have been used in every soil condition and are supplied to suit designed loads ranging from 10
tonnes to more than 1,000 tonnes per pile. To support a foundation, the piles are driven to the required resistance or seated in rock, and filled with concrete and steel piles are suitable for use with most standard pile driving equipment. However in the large diameters, (e.g. 914.4mm/ 36 inches and above), they are usually referred to as caissons and are often drilled in, jetted or jacked, or a combination of these methods may be used.

A variety of different end closures can be supplied with these piles, either welded on or supplied loose, depending on the customer’s requirements. Experienced contractors have used flat end plates successfully under practically all soil conditions. They are economical, drive straight, and generally do not require reinforcing. Piles with flat plates are not easily deflected by boulders or other obstructions. Another type of end closure is the cone point. It is sometimes used for driving through high resistance strata such as shale or rock formation, and for end bearing in bedrock. However, cone points are more expensive than flat plates and are generally no easier to drive. Fabricated crosses welded on to flat plates are often used when piles are to be seated on solid rock. A cross welded to a flat plate penetrates soft material to reach bedrock. Open end piles are preferred when displacement of soil is undesirable. They are ideal for building foundations adjacent to other structures. Pipes can also be supplied with reinforcing collar or cutting shoe welded to the lower end when conditions require.

Steel pipe piles drive straight because of their high beam strength and low wall stress. In addition, the diameters of the piles are manufactured to close tolerances and cut-offs of any length can be economically salvaged to extend short piles or to make whole new piles. As steel pipes are welded products, only steels of the highest welding quality are used. As a result, field splices are easy to butt weld. Different diameters and thickness are also available, giving a large range of combinations to choose from.