What method is an allowed technique for installing pretensioned bolted joints?

The calibrated wrench method is a recognized technique for installing pretensioned bolted joints, primarily because it provides a reliable means of ensuring that the correct amount of tension is applied to the bolt. This method involves using a wrench that has been calibrated to apply a specific torque that corresponds to the required bolt tension.

When using the calibrated wrench method, it is crucial that the wrench is properly set up and regularly checked for accuracy to maintain the integrity of the bolted connection. Ensuring that bolts are adequately pretensioned is vital, as it helps to prevent issues like joint separation or slippage under load, which can lead to structural failure.

Other methods like impact wrenches, while fast and effective for some applications, do not allow for precise control over the tension applied and can lead to over-tensioning or under-tensioning of bolts. The hydraulic method, although effective in certain situations, may not always provide the necessary precision for specific applications. The torque wrench method is also valid, but it may not project the same level of reliability for achieving the required pretension when not calibrated. Therefore, the calibrated wrench method stands out as the preferred and accepted technique for ensuring the correct pretension in bolted joints.