I. Preparation before tightening
Tool selection: Select a suitable wrench according to the nut size (e.g., 20-30 N·m torque for M8 nuts). A torque wrench is recommended for high-temperature and high-pressure systems.
Cleaning and inspection: Clean the flange surface and bolt holes, ensuring they are free of oil and rust.
II. Tightening steps
Symmetrical tightening: Operate in three stages diagonally:
Stage 1: 50% torque for initial positioning (e.g., 10-15 N·m for M8 nuts).
Stage 2: 80% torque for compaction (e.g., 16-24 N·m for M8 nuts).
Stage 3: 100% torque for locking (e.g., 20-30 N·m for M8 nuts).
Checking uniformity: Measure the flange clearance with a feeler gauge, ensuring the error is within the allowable range (e.g., ≤0.3mm for aluminum washers).
III. Precautions
Torque standard: Strictly follow the manufacturer's requirements to avoid overtightening or loosening.
Tool Selection: A torque wrench is required for high-temperature and high-pressure systems; a box wrench can be used for ordinary equipment.
Regular Inspection: It is recommended to check the equipment every 3 months after replacement to ensure long-term stability.
