A weld data management and monitoring system that supports weld data trend analysis. Weld data is collected for each weld operation and a trend index equation is applied to the data to calculate a composite number for the operation. The composite numbers for numerous welds may be plotted and analyzed to detect and evaluate weld trends over a specified period of time. In an example embodiment, the trend index equation uses the weld heat input, current, resistance, and time values to calculate the composite number. Trend data may be analyzed to identify a time when variances, whether within or outside specified tolerances, occurred. The ability to detect and analyze variances in weld operation data during a specified period of time may assist the manufacturer in identifying and resolving problems related to the weld equipment as well as other manufacturing processes or operations that may have caused variances in weld operations.