I. Pre-installation Preparation
1. Cleaning and Inspection: Clean rust, oil, and burrs from the installation contact surfaces to ensure a smooth and flat surface. Inspect threads for damage and debris. If necessary, degrease and lubricate the threads to reduce tightening friction.
2. Accessory Verification: Confirm that the matching bolt specifications are correct and that the selected gasket size is compatible with the flange. Do not stack multiple gaskets; ensure the gasket is centered.
II. Core Installation Steps
1. Positioning and Pre-tightening: First, tighten the bolts at four diagonally opposite points by hand to position and center the gasket. Then, install the remaining bolts and hand-tighten until the load is balanced, ensuring at least two threads are exposed on the outer side of the nut.
2. Gradual Tightening: Tighten in at least three stages using a diagonal staggered tightening method, following a load gradient of 50% → 80% → 100%. Finally, tighten again under full load along the circumference to avoid uneven stress in certain areas.
3. Tool Compatibility: For general applications, a box wrench is sufficient. For high-temperature and high-pressure conditions, a torque wrench or bolt tensioner is required. Calculate the rated tightening torque in advance and record it.
III. Key Precautions:
1. After tightening, the exposed length of the bolt should be controlled within one thread pitch. Ensure all nuts are installed in the same direction.
2. Under high-temperature conditions, heat tightening must be performed according to the corresponding temperature requirements to avoid sealing leaks after operation.
