METHOD FOR THE SHEATHING OF STEEL PIPES WITH THERMOPLASTIC SYNTHETIC MATERIAL

摘要

The disclosed method is particularly applicable for jacketing pipes of a diameter of between 50 mm and 500 mm and is provided for high jacketing speeds and high throughputs. The pipe is heated initially to a temperature at least sufficient to cause a subsequently applied epoxy resin-curing agent powder blend to me a coherent and uniform epoxy coating is desired which may require subsequent heating of the epoxy coating. The epoxy coating will cure at a temperature from 145 degrees Centigrade to 155 degrees Centigrade within 50 to 70 minutes and the layer thickness should be between 30 and 50 micrometers. Prior to applying the jacket, the thermally produced reaction products must escape; this is ensured by an infrared radiation step which raises the temperature to about 200 degrees Centigrade. In the case of a thermo-sensitive interior of the steel pipe, this heating step provides not only for the evaporation of reaction products, but it is the same step which makes sure that the preheated and slightly melted powder obtains sufficient fluidity.