What do you mean by minimum tensile strength?

Tensile strength is determined from testing a large number of samples. Some will fail higher or lower than others, and an average strength is determined. Minimum tensile strength is usually calculated from statistics using a Weibull probability analysis. In this case the minimum tensile strength usually is reported as the Weibull A value, which is the value at which 99% will survive with 95% confidence. Weibull B, usually based on fewer samples, is the minimum value determined to survive with 90% reliability and 95 % confidence.