Tools are very carefully designed and inspected to be in accordance with the American Society Mechanical Engineers (ASME) standards, which provide values for strength as well as dimensions. In practice, our designs pack as much strength as we can into the allowable space. This means that we are often substantially stronger than the value in the standard.
The difference between the wrench breaking and not breaking may be just a few percentage points in strength, so the factors discussed here might sound minor, but they can produce very substantial results in time, money, and safety.
We cannot do without fasteners to hold things together and fasteners must be turned with wrenches. Wrenches do not appear to have changed much in 50 years, but fasteners certainly have. Most fasteners used to be made with steel with an ultimate strength of 60,000 psi.
It’s common knowledge that if you try too small of a wrench on a fastener, it won’t fit, and you’ll lose time changing wrenches
For the professional who services equipment and has trouble removing 12-point fasteners, there are a few things that can be done to help make it easier.
Not all wrench breakage should be blamed on users. Fasteners have gotten stronger and are being tightened to higher torques. In addition, they are being turned with wrenches designed and built before today’s stronger fasteners were developed.