The final acceptance criteria for quality may be determined by agreement between the manufacturer and the user. Prior to that accepted industrial standards are frequently referenced for possible use in the various applications. One location for these standards is the American Welding Society. AWS publishes technical standards. Many applications with helpful start up data can be found in:
AWS Standard C1.1- Recommended Practices for Resistance Welding
This standard will include tables with data that is applicable to many applications in industry.
This is an excerpt from a much larger table. There are many tables on many steels and nonferrous materials. Each table offers the same and more information on set up and testing including weld nuggets, shear strength and other weld schedule related data. The processes included are Spot, Projection, Seam , Butt and Flash welding.
Reference: AWS Standard C1.1 Recommended Practices for Resistance Welding