Correct Torque Application on Flanges
Proper torque application is essential for ensuring leak-free flange connections offshore.
Incorrect torque can lead to:
- Leaks
- Gasket failure
- Bolt stretching
- Equipment vibration
- Rework and downtime
- Potential hydrocarbon release
This scenario teaches crew members how to apply torque safely and correctly using hand tools.
1. Understanding Torque
Torque is the rotational force applied to tighten bolts.
It ensures:
- Proper gasket compression
- Even sealing
- Correct preload on bolts
Too much torque = damage
Too little torque = leaks
2. Required Tools
- Combination wrenches
- Ratchet and socket set
- Torque wrench (manual or digital)
- Flange alignment tools
- Gasket and bolt size references
- PPE (gloves, safety glasses)
3. Step-by-Step Torque Procedure
Step 1: Preparation
- Verify correct gasket type and size
- Ensure flange faces are clean and undamaged
- Check bolt condition (no stretching or corrosion)
- Lubricate bolt threads if required by procedure
Step 2: Insert Bolts and Hand-Tighten
- Insert all bolts
- Tighten by hand to ensure even seating
- Make sure the gasket is centered
This ensures no cross-threading or misalignment.
Step 3: Apply Torque in a Star/Cross Pattern
Always tighten in a crisscross sequence to apply even pressure.
Sequence example for 8-bolt flange:
1 → 5 → 3 → 7 → 2 → 6 → 4 → 8
This prevents gasket distortion.
Step 4: First Torque Pass (Low Setting)
- Set torque wrench to the initial value (e.g., 30–40% of final torque)
- Tighten each bolt in sequence
- Use controlled, steady force
Step 5: Second Torque Pass
- Increase torque to 70–80%
- Repeat cross pattern
Step 6: Final Torque Pass
- Apply full required torque
- Listen for “click” on mechanical torque wrenches
- Ensure no bolt is forgotten
Step 7: Re-Torque After Settlement (if required)
- After system warms or vibrates
- Always follow facility procedure
4. Safety Considerations
Body Positioning
- Pull rather than push
- Keep face and body out of line-of-fire
- Maintain stable footing
- Avoid awkward twisting
Tool Handling
- Never use cheater bars unless approved
- Ensure torque wrench is calibrated
- Remove slop and confirm snug fit
Pinch Points
- Keep hands away from bolt heads
- Avoid fingers between flange faces
5. Common Mistakes to Avoid
- Skipping final torque pass
- Tightening bolts in a circle instead of cross pattern
- Using adjustable wrenches for torque
- Over-tightening without calibration
- Ignoring slippage or worn sockets
6. Learning Objectives
After completing this scenario, trainees should understand:
- Proper bolt-tightening sequence
- How to use torque wrenches safely
- Correct body alignment for torque tasks
- How to prevent leaks and equipment damage
- How to identify and correct common mistakes