Carbon steels having a carbon content in excess of 0.32% (ladle analysis) or a carbon equivalent (C + 1 .4 Mn) in excess of 0.65% (ladle analysis) shall be preheated to
the temperature indicated by the welding procedure.
Preheating shall also be required for steels having lower carbon content or carbon equivalents when the welding procedure indicates that chemical composition, ambient
and/or metal temperature, material thickness, or weld-end geometry require such treatment to produce satisfactory welds.