Cleaning and Handling Proper preparation of the surface of the steel by sand or grit blasting is necessary where rapid weathering and uniform appearance are desired. By removing all mill scale, the surface oxide will start forming on hot-rolled steel as it is exposed to air. This preparation is recommended especially for the highly visible exterior or fascia members of bridges. Care should be taken while handling Weathering Steel in the field to avoid unsightly gouges and scrapes. The material should be kept as clean as possible away from mud, grease, oil, paint, concrete, mortar splatter and other foreign substances to minimize costly cleaning. Paint or crayon identification marks should be made in locations not visible on the finished structure. Otherwise, these marks must be removed from the visible surfaces during the final cleaning operation. Storage in transit, yards or at job sites should be minimized. When storage is unavoidable, uneven weathering can be minimized by positioning the material in an exposed area with good drainage. Blocking, to avoid contact with the ground, is essential. Cover cloths also may prevent water staining and dirt accumulation, thus minimizing problems of an initial, non-uniform weathered appearance. In general, the corrosion resistance and appearance of Weathering Steel is not affected by cleanliness. Mill scale and minor soilage will weather off naturally on exposed surfaces and need not be a concern for interior members of low visibility. However, cleanliness and surface preparation are important where an early, uniform appearance is desired. Joining, Forming and Stiffening Good connection, forming and stiffening details are important with Weathering Steel. Ledges, crevices and pockets that hold water, water-laden debris or condensation for an extended period time must be avoided. The oxide coating will not develop on surfaces that are continually wet or covered with debris. Under such circumstances, corrosion continues in these areas. Welding Weathering Steel is readily weldable by the submerged-arc, shielded metal-arc, gas metal-arc and flux-cored arc welding process. Procedures are similar to those used for other low-alloy structural steels. Low-hydrogen electrodes are specified by the American Welding Society for welding Weathering Steel. Suggestions on minimum preheat are contained in the latest revisions of ANSI/AWS “Structural Welding Code” D1.1 and the ANSI/AASHTO/AWS “Bridge Welding Code” D1.5. For bare steel applications, when the weld is required to have strength, corrosion resistance and weathered appearance similar to that of the base metal, special electrodes must be used. When matching strength is required, and color match and corrosion resistance are not important, E70, E80, E90, E100 or E110 lowhydrogen electrodes may be used. These electrodes also work for the underlying passes in multiple-pass welds. However, when color match and corrosion resistance are important, appropriate alloy electrodes must be used for the final two exposed top layers. All welding should be consistent with AWS recommended procedures including adequate edge preparation and preheating, the selection of proper flux (when applicable) and the use of properly dried, lowhydrogen electrodes and fluxes.