| 摘要 |
PROBLEM TO BE SOLVED: To obtain a Zn or Zn-Al alloy plated steel pipe having a good coated appearance and corrosion resistance inclusive of the seam-welded part even if the degreasing, water washing and phosphating as the pretreatment for the conventional powder coating are omitted and a method for producing the pipe. SOLUTION: A Zn or Zn-Al alloy plated steel with an org. film at >=0.5g/m<2> or a urethane resin contg. 5-15mass% polymer powder formed on the surface is used as the base material for the seam-welded steel pipe. The seam-welded part is coated with Zn or Zn alloy at 30-200g/m<2> , and then an org. resin at 0.5-4.0g/m<2> is formed on the Zn or Zn alloy coated region to obtain the Zn or Zn alloy plated steel pipe excellent in powder coating suitability. A water- dispersible or soluble org. resin is sprayed as the grains having <=500μm diameter on the Zn or Zn alloy coated part at >=40 deg.C to form the org. resin film by this method.
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