NKK's New Arched Drilling Method for Pipeline Laying
A new technique for laying pipelines under rivers and canals was recently introduced by NKK corporation of Japan and its civil engineering subsidiary, Nippon Kokan Koji Kk (NKKK). They have also developed specially adapted engineering machinery to support the new pipeline laying method, which was jointly developed with Sacramento, California based Cherrington Corporation.
"Usually, pipelines are laid across an expansive river by building a special bridge or using a shield-tunneling method. Both these methods are expensive and time consuming. The new pipelaying method we developed uses a directional drilling technique similar to that used in oil exploration, to allow digging of curved tunnels," explained Mr T Goda, general manager of NKK representative Office in Singapore.
According to Mr Goda, "a drill head is attached at the front-end of the pilot pipe to dig horizontally from the ground surface without digging a vertical pit. Drilling can be controlled to curve smoothly under rivers. A Pipe of the specific diameter is then pulled through this pilot pipe and because the direction of the drill head can be controlled, pipeline routes can be accurately determined."
The new method boasts larger-diameter pilot pipes and improved reaming, which improves efficiency in pipeline laying. It is also expected to reduce time and cost of laying pipelines.
The technical collaboration with Cherrington is the latest in pipeline laying technology since NKK started development of drilling systems for various pipe diameters, soil types, and other conditions since the mid 1960's. Cherrington has expertise in pipeline laying, having completed over 300 projects worldwide. NKK holds the exclusive right to develop and market the new method in Japan, which is available under the brand, NK-RAPID.
NKK and NKKK have also developed easyto- use machinery which can be specially adapted to engineering requirements and operating environments in both Japan and the US. Actual projects will be carried out by a team of engineers from NKK, NKKK and Cherrington. The NK-RAPID method is available for immediate application and is presently used in a Hong Kong gas pipeline project.
NKK Corporation, Japan's second largest steelmaker, is a diversified company specialising in steelmaking, heavy industries, shipbuilding, advanced materials and urban development, electronics and biotechnology.
