Polymer tapes are used to insulate the oil pipelines over a wet base coat which has just been applied or over a dried out coat in accordance with the Standards and Technical Documentation for these materials.
When applying the covers and insulating tapes, no corrugation, deformations, wrinkles, looping are allowed, the overlapping width for a one-layer cover is min 3 cm, while for a two-layer cover it can be less than the width of the tape plus 3 cm. Constant tension with load should be applied for the tapes and covers to wrap all surface and to have a water-tight overlapping.
If the protective covers do not have a reliable contact with the insulating materials, they should be fixed at the end of the material, and if it is necessary, then they should be fixed in every 10 - 12 m with special bandages and glues.
Oil pipelines are insulated with asphalt mastic based material right after the base coating is dried out. Asphalt mastic is evenly applied along the pipeline and in its perimeter with no inclusions and air bubbles.
Protective rolled material should cover the pipeline and the asphalt mastic should be armored with glass-fiber wrapping with no riffles, wrinkles and corrugations.
The thickness of the asphalt insulation layer which covers a pipeline, its adhesiveness, uniformity and penetration depth of glass-fiber wrapping into a mastic layer mainly depend on mastic's viscosity which can be adjusted with temperature in a bath of coating-and-wrapping machine due to the ambient temperature.
It is necessary to use a Rubber Neck Gasket (PMTD-R) to insulate the crossings under the railway roads and highways, which seals the spacings between the carrier pipe of the main pipeline and the casing. Operating temperature is from -60 °C to +50 °C. A protective Cover of Water-Tight Neck Gasketshould be used to avoid the gasket defects due to soil pressure or any other mechanical impacts during a product's treatment.
Insulating works in winter
In winter time the repair works of the pipelines require advanced protective covers.
With the insulating materials it is important to match the material characteristics with the temperature of the pumping oil and the ambient temperature during the insulating works.
Insulating works should be combined with some other works with no significant trench digging in front of insulating jacket.
A pipeline part which has already been insulated should be laid on a 20 cm thick cushion from soft soil and be covered with the soil at the height of 20 cm to protect the pipeline from mechanical damages.
With asphalt mastic, when an insulated pipeline part is put at the bottom of the trench, it should be covered with soil, thus protecting the insulation.
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