U.S. Department of Transportation
Federal Highway Administration
Based on preliminary results of recent research and the actual observations in the field, the use of electro-slag \weldments on main structural tension members will not be permitted on Federal-aid projects. This restriction will continue until such time as the quality of this weld can be insured by possible modification in the welding process and/or improvement in the inspection and quality control procedures which appear necessary at this time.
Because the economic advantage of this type of weld will be lost by this restriction, other types of welding processes in thicker material will become costly and provide opportunity for welding complications. Accordingly, the use of main member tension material in excess of 2-inch thickness is to be avoided wherever possible by modification in the structural components or in the material makeup of the individual structural member.
The above restriction will be applicable to future projects and those currently in the design, bidding, and construction stages, effective as of the date of this bulletin.
Nonredundant main load carrying tension members in existing structures that are known to have been welded with electro-slag process should be subjected to rigorous NDT(radiography and ultrasonic) inspection as soon as possible.