@LZ – Thank you for your concern with regard to the accuracy of information on the topic of hydrogen embrittlement provided on our website. The information Adam provided previously is accurate, however his interpretation of the data may be a bit misleading. The fact that A193 grade B7 has no maximum tensile strength requirement provides no insurance that the actual strength of a given bolt (or lot of bolts) could exceed 150 ksi in ultimate tensile strength. However, the fact that the specification carries a maximum Rockwell C35 value in theory will limit the tensile strength to somewhere in the mid 150 ksi range. There is no magical line at 150 ksi tensile strength where if a bolt exceeds that value, it is automatically going to be susceptible to hydrogen embrittlement. On the contrary, you will see that based on a couple references I will present, the point at which hydrogen embrittlement may occur when a quenched and tempered medium carbon alloy fastener is galvanized appears to be at a much higher tensile strength than 150 ksi.