Mark
March 1999    

New Steel Screw-Pile Marketed

NKK's steel screw-pile being driven into ground
NKK's steel screw-pile(right) being driven into ground (left) to form a building foundation

NKK has developed a new type of steel screw-pile for use in building foundations and has begun active marketing of the product, which ensures eco-friendly, economical installation work.

Although the marketplace for foundation piles for buildings is large, the application of steel piles has been somewhat limited. The newly developed screw-pile with wing-shaped circular plates on the tip permits easy driving into the ground with no need to remove soil. It also ensures enhanced bearing capacity and can compete on an equal footing or better with conventional concrete piles.

The advantages of using steel screw-piles are as follows.

  • The structural design of the wing tip is simple but physically strong, and the manufacturing cost is low.

  • With the wing tip working like a screw, it is possible to insert the pile into the ground without removing any residual soil, ensuring reduced noise and vibration during installation.

  • Since the area of the wing tip is four times bigger than steel pipes, it has greater bearing capacity, enabling the reduction of construction costs compared with conventional piling methods.

In installing the steel screw-pile (pipe 318.5-508.0mm in diameter with the wing tip having twice the diameter of the steel pipe), the unit is inserted into the ground like a screw by rotating the pile shaft with an auger. In comparison with other certified pile methods, the bearing capacity of the wing tip is 1.6 times stronger in sandy soil and 2.4 times stronger in gravel soil.

In November 1998, NKK obtained the Construction Ministry certification for its steel screw-pile based on the Building Standards Act. With this certification, the company began marketing the product, mainly targeting medium high-rise (three-to eight-story) buildings. Four buildings are already scheduled to use the new product.

NKK has been developing a series of unique steel tubular products (piles, columns, poles and pillars) for use in the construction and civil engineering sectors, such as NKTB, HYSC, Nejeal,Eagle, and NT Column, satisfying customer needs for improved earthquake-resistance and lower construction costs. NKK expects its new steel screw-pile will prompt great demand in the market.

To further promote the market acceptance of the steel screw-pile and its proper operations, NKK has joined hands with five major pile installation companies to form the Tsubasa (steel screw-pile)Association. The number of member companies will be increased in the future depending on demand trends.

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