ABSTRACT:

The paper discusses problems of the pipeline construction In severe environments and considers approaches to selection of materials and construction techniques for arctic pipelines. In particular, it covers such aspects as pipeline burying in frozen soils with the use of ditch bottom polymer foam paddling and pipeline anchoring in permafrost, with some anchor design configurations illustrated. Mention is made of the use of enameled pipes and their Joining methods. Useful application of brazing is reported.

INTRODUCTION

At present, high pace of construction and quality of pipelines laid under extreme climatic conditions such as those existing In the USSR arctic and subarctic areas, permafrost, bogged and flooded terrains of the West-Siberian region are feasible only through using new materials and procedures. The Arctic dry land is a terrain with widespread permafrost soils having a temperature down to -10 deg C, laced with bogs, lakes, numerous streams and creeks. Grounds of Arctic regions vary. The surface is composed of permafrost sands, loams, sand loams, peats, gravel, etc. The ground components are ice-consolidated with the ice contents factor being of 0.4 - 0.8. On the top, the grounds have the tundra moss-and grass cover. In summer, the grounds are subjected to intense thawing, with seasonal thaw penetration depth of 2 - 2.5 m. With thawing, they lose their load carrying capacity. The tundra topography is mostly level, and in summer, the terrain is flooded over vast areas. Accomplishment of construction jobs in these adverse environments involves extremely serious difficulties raised by the necessity to adhere to stringent ecological requirements. Basic requirements to be handled when laying pipelines in Arctic regions With very sensitive and easily destroyable tundra vegetation cover as follows: preserving moss-and-grass cover In its natural state, providing drainage facilities, and doing the job In winter on frozen ground, with using ground-or snow-built work pads. Special environment of construction jobs In Arctic conditions specify requirements for the pipes, procedures and facilities.

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