Bolt tool usage and bolt installation requirements
After installation, the torque of the critical part bolts needs to be re-measured, and the anti-loosening mark status should be checked regularly.
Release Time：
2025-05-30
Bolt Tool Usage and Installation Requirements
I. Bolt Tool Usage
Tool Selection and Preparation
Select matching tools according to bolt specifications: Use torque wrenches for regular bolts (e.g., 500N·m torque hydraulic wrench for M45 bolts), and special tensioners for high-strength bolts.
Check tool condition: For hydraulic tools, ensure that the oil cleanliness meets the standard (ISO VG46 hydraulic oil), oil pipes have no cracks, and joints are not loose.
Operation Process
Cleaning and Pre-tightening: Clean the bolt holes and threads, manually pre-tighten until snug to avoid tool slippage due to forced pressure.
Step-by-step Tightening
Ordinary bolts: Tighten gradually in three steps of 30%, 70%, and 100% torque using the "cross method" to ensure even force distribution.
High-strength bolts: Use the initial tightening (60%-80% axial force) → final tightening (100% axial force) process, and mark for leak detection.
Torque Control: Strictly set the torque according to the specifications, for example, for M90 bolts, refer to the hydraulic wrench pressure table to adjust the system pressure.
Hydraulic Tool Operation Points
Bolt tensioners require verification of the exposed bolt length (≥1 times the bolt diameter), and flange bolts need to be stretched synchronously to avoid uneven load.
When tightening hydraulic joints, the compression fitting connection needs to match the pipe size (6-42mm) and material (carbon steel preferred).
II. Core Requirements for Bolt Installation
Basic Standards
Permanent connection bolts require washers: ≤2/≤1 flat washers are placed on the bolt head/nut side respectively, and spring washers must be added to dynamic load parts (close to the nut).
Bolt insertion direction rules: From inside to outside for horizontal structures, from bottom to top for vertical structures; aligned with the line direction for planar structures.
Accessory Usage Standards
Scenario Washer Configuration
Electrical connection Hot-dip galvanized bolt + 2 flat washers + 1 spring washer (nut side)
Channel steel inclined surface connection Inclined washer + flat washer, ensure that the supporting surface is perpendicular to the bolt
I-beam long hole connection Square washer × 2, both ends of the double-headed bolt are equipped with flat washers
Installation Steps and Control
High-strength bolt installation:
Remove burrs and rust from the connecting surface and keep it dry.
The number of temporary bolts ≥ 1/3 of the total number and ≥ 2, and high-strength bolts are prohibited from being used as substitutes.
Final tightening must be completed on the same day, and the梅花头 of torsion-shear bolts must be broken off.
Flange bolts: After numbering, load in stages according to the symmetrical cross method, and finally retighten in clockwise order to the target load.
Environment and Quality Control
When humidity > 80% or temperature < -10℃, antifreeze hydraulic oil needs to be replaced or work needs to be delayed.
Bolt straightness deviation ≤ 0.05mm/m, and the flange circumferential gap needs to be uniform throughout (error < 0.1mm).
III. Prohibited Actions and Risks
Strictly prohibited operations: Over-torque tightening (easy to break), installing high-strength bolts in the rain (friction surface failure).
Risk cases: Misalignment of the hydraulic tensioner leads to flange deformation due to uneven load; the spring washer is installed backward, causing loosening accidents.
Note: The torque of key parts bolts should be re-measured after installation, and the anti-loosening mark status should be checked regularly.
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Email：cs@fomadon.com
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