Multi-step combined mechanical/thermal process for removing coatings from steel substrates with reduced operating and capital costs and with increased refrigeration speed and efficiency

摘要

To remove a thick insulating coating from a steel pipeline, with high efficiency and speed, multiple cooling and scraping steps are performed sequentially. In a first cooling step, a low temperature coolant is sprayed onto the coating for a time sufficient to cool only a portion of the coating to a temperature below the embrittlement temperature thereof. After scraping away the embrittled outer layers of the coating, subsequent cooling and scraping steps are performed until all of the coating has been embrittled and removed. It has been found that the time required for removing the coating by use of such multiple spraying and scraping steps is substantially less than that where the coating is to be embrittled in a single step.