| 摘要 |
PROBLEM TO BE SOLVED: To prevent the oxidation of a steel pipe due to the residual air at the covering part of materials to be covered from developing by a method wherein covering material made of a particulate thermoplastic resin is supplied and filled in a gap, which is formed between the outer peripheral surface of steel pipes to be covered and the inner surfaces of employed split molds, and heated to be fusingly bonded and solidified onto the outer peripheral surface of the steel pipes to be covered. SOLUTION: By installing an annular burner so as to cover the butt-weld WP of steel pipes to be covered Pa and Pb and its peripheral part, the above-mentioned parts are heated with the annular burner for a predetermined period of time. Next, the annular burner is removed from the steel pipes Pa and Pb to be covered and then a split mold 8 is installed so as to cove the heated weld WP and its peripheral part. Next, a particulate thermoplastic resin CP is supplied from a covering material supplying hole 6 of a split mold 8 and filled in a gap A formed between the inner surface of the split mold and the outer surface of the steel pipes to be covered Pa and Pb. Then, the resin CP is bonded with the weld WP and its peripheral part by fusing the proper amount of the filled resin CP. Further, by allowing to gradually cool the split mold 8, the split mold 8 is removed so as to form the covering with the resin CP. |
