Cladding cylindrical objects, esp. pipeline sections with insulation - in continuous process densifying and protecting foamed layer surface

摘要

A foam forming mass of insulating material is applied to a cylindrical object, esp. a continuous run of pipes for transporting petroleum, natural gas, etc., whilst it is moved lengthways relatively to its central axis, on which it is also rotated. A layer of foam forming material is sprayed on first and this, aftr it has been allowed to expand, is wrapped in a strip of flexible sheet material. Sufficient tension is applied through the strip on to the expanded material whilst it is still deformable, to densify the surface zone of the foam. This densifying operation includes the application of sufficient pressure to raise the final density in the surface zone to 10-25% above the density which it would have had, had it been allowed to expand unhindered. The foaming material is applied at a consistently uniform thickness to the pipe and without damage to the cell structure. The insulation is protected against damage by winding on a ribbon or adding an extruded surface coating. Desired zones of the object can be easily marked so that they can be found after covering, damaging the insulation.