The most common application in the industry is to use Spirax® locknuts in combination with standard bolts to form a locklock thread system. Let us first reexamine this relationship. In Figure 1.0, the tooth tip of the male thread of the standard bolt is pressed against the 30 ° wedge surface of the female thread. Because the contact surface is small, the contact stress is large. Under the action of torsional moment, the tooth tip of the bolt will plastically deform.