in order to utilize separately steel pipe and coating resin as recycling resources , resin - coated steel pipe , which is produced by adhering a thermo - plastic coating resin on the surface of steel pipe with an adhesive , is heated by high - frequency induction heating to at least the melting temperature of the coating resin , and the coating resin is scraped off while the inner layer thereof is in a melted condition and the outer layer is in a softened condition . coating resin and steel pipe can be recovered without the composition thereof being damaged . the scraping of coating resin is complete and efficient and requires only minimal energy since it occurs when the inner layer of the coating resin is in a melted condition and the outer layer is in a softened condition .