A tension calibrator is necessary where bolts are installed in which kind of joints?

A tension calibrator is essential for pretensioned joints because these types of connections require a specific amount of bolt tension to ensure that the joint can effectively carry the loads it is designed to handle. In pretensioned joints, bolts are tightened to a predetermined tension level before the joint is subjected to service loads. This tension creates a clamping force between the connected members, which helps compensate for any loads or stresses that may be applied over time.

By using a tension calibrator, an installer can accurately measure and achieve the required tension in the bolts. This ensures that the joint maintains structural integrity and performance, as insufficient tension could lead to joint separation or failure under load. In contrast, loose joints, temporary joints, and non-structural joints typically do not require such precise tensioning, as their load-carrying requirements and performance expectations differ from those of pretensioned connections.