Care should be taken when using them because plating finishes can act as a lubricant resulting in lower torque values corresponding with higher tensile values. Thus a lower torque value could result in a higher than expected tensile load which in some cases could be greater than the ultimate tensile strength of the fastener resulting in failure. 

What must also be taken into consideration is the variation in stress area between minimum and maximum rolling diameter - the smaller the fastener the more significant this becomes.

The fastener should not therefore be tested by use of torque to failure and then computing the tensile load. Instead a direct axial tensile load to failure should be applied. The tables represent maximum tightening torque values. You should always thoroughly test the products to ensure suitability for your particular application.