| 摘要 |
<p>Prior to welding a shrink wrapping tube(7) is pushed over one of the steel tubes(2), then the tube ends are welded together and an epoxy coating applied to the welding zone(3). Adhesive(14) is then applied to the welding zone as far as the ends of the tube insulation layer(6) on both sides of the weld. The shrink wrap tube is moved along the tube until it covers the welding zone and the adhesive layer. Heat shrinking of the wrapping tube onto the welding zone forces adhesive out of the wrapping tube and distributes it over the epoxy coating. Tube ends are cleaned and the welding zone is heated before applying epoxy resin, preferably by inductive or conductive methods. Epoxy resin(12) and adhesive(14) layers are applied as powders which are blown through screen openings(8) by a gas(16), preferably oxygen or nitrogen, warmed to 30-60degreesC. Epoxy resin and/or adhesive powder have a particle diameter of 10-20 microns. Powder can also be applied by fluid bed coating. Final thickness of the epoxy resin layer is 10-100 microns, preferably 50 microns. Epoxy resin and adhesive may be applied simultaneously. An Independent claim is included for the construction of insulation over a welded joint between insulated, triple layer corrosion-protected steel tubes which comprises a shrink wrap tube covering adhesive and epoxy resin in the weld area..</p> |
