ABSTRACT
The most common long distance oil- and gas- pipelines in Russia are so-called channelless lines. In view of the fast development and improvement of construction technology, there is a need for more effective materials for thermoinsulation, sufficiently lightweight and strong, and at the same time possessing a combination required for efficient and reliable performance of underground lines. Foamed plastics based on thermosetting phenolic resins have been found to be such a material. Many years of field testing proved it to be effective in terms of thermoinsulation, energy saving, and low cost. New generation of phenolic foams for pipelines is based on in situ (foaming-in-place) technology, having very uniform cellular structure, low brittleness and corrosive activity and much higher mechanical strength. The main technical requirements for plastic foam insulation are discussed: apparent density, compressive strength, moisture content, thermoconductivity, and etc. Results of model laboratory tests under conditions imitating the service of heat insulated pipes in real channelless lines are presented, and these data are compared with foam concrete insulation. Data on heat conductivity of phenolic foams at broad range of moisture content and apparent densities are discussed, as well as results of water and moisture sorption. Briefly discussed is a pouring technique for carrying out of phenolic foam insulation on metal pipes in situ at different ambient temperatures (from -30° C to +30°C). Some recommendations and conclusions based on long-term application of pipe insulation in Russia are given.
