1. Tightening method: Also called the additional tightening method, it is suitable for inspection of important fasteners.

The tightening torque of bolt connections in important parts should be inspected using the tightening method according to the technical conditions of installation. Inspection method: use a torque wrench to steadily increase the torque (avoid impact). When the nut or bolt begins to rotate slightly, its The instantaneous torque value is the largest (because it has to overcome static friction). If it continues to rotate, the torque value will fall back to a short-term stable state. The torque value in this short-term stable state is the torque obtained by inspection.

Features: The operation is simple, but the quality inspection personnel must be skilled, that is, they must apply force evenly and accurately read the "short-term steady state torque value".

2. Marking method: also called reset method, scribing method, corner method, etc., suitable for inspection of key fasteners

For critical fasteners, use the marking method with a torque wrench for inspection. Before inspection, draw a line on the head of the bolt or nut and the connecting part to be inspected to confirm the original position of the bolt head or nut and the connecting part. Then remove the bolt or nut, and then use a torque wrench to tighten the bolt head or nut to the alignment position. The maximum torque value at this time is multiplied by 0.9 to 1.1 to obtain the torque obtained by inspection.

Features: The technical level is not high. You must draw a line to determine the original position, then loosen and tighten again. The operation is cumbersome and is not suitable for some fasteners with anti-loosening functions.