Overhauling procedure of heat exchanger

Heat Exchanger Overhauling Procedure:

Overhauling a heat exchanger involves inspecting, cleaning, repairing, and reassembling it to restore optimal performance. This process is crucial for maintaining efficiency, preventing failures, and extending the equipment’s lifespan.

Download Handbook: Handbook of heat exchangers

?? Step-by-Step Overhauling Procedure:

1. Preparation & Safety Measures:

? Shutdown & Isolation:

• Depressurize and drain the heat exchanger.
• Isolate it from connected systems (steam, water, oil, or gas).
• Ensure proper Lockout-Tagout (LOTO) procedures.

? Safety Precautions:

• Wear PPE (gloves, goggles, protective clothing).
• Ensure proper ventilation for chemical cleaning.
• Follow confined space entry procedures (if applicable).

? Gather Required Tools & Equipment:

• Torque wrenches, gaskets, cleaning tools, and chemical cleaners
• Pressure testing kits and NDT (Non-Destructive Testing) equipment

Download Handbook: Handbook of fundamentals of heat exchanger design

2. Disassembly:

? Remove External Components:

• Disconnect inlet/outlet piping and valves.
• Remove insulation and covers (if applicable).

? Unbolt & Separate Exchanger Parts:

• For Shell & Tube Exchangers: Remove channel cover and floating head cover. Pull out the tube bundle carefully.
• For Plate Heat Exchangers (PHE): Loosen tie bolts and separate the plates.

? Inspect for Damage:

• Check for leaks, corrosion, fouling, and wear in tubes, plates, gaskets, and shell.

3. Cleaning & Maintenance:

? Tube Side Cleaning:

• Mechanical Cleaning: Use brushes, rods, or hydro-jetting to remove scale and deposits.
• Chemical Cleaning: Circulate cleaning solutions (acidic for scaling, alkaline for organic fouling).

? Shell Side Cleaning:

• Use high-pressure water jets or steam cleaning.
• Inspect and remove sludge or debris.

Download Handbook: Heat exchanger design handbook

? Plate Cleaning (For Plate Heat Exchangers):

• Soak in a chemical cleaning bath.
• Scrub gently and rinse thoroughly.

4. Inspection & Repair:

? Visual Inspection:

• Look for pitting, cracks, or erosion on tubes and plates.

? Non-Destructive Testing (NDT):

• Dye Penetrant Test (DPT): Detects surface cracks.
• Ultrasonic or Eddy Current Testing: Identifies internal flaws in tubes.

? Tube Repair & Replacement:

• Plug or replace damaged tubes.
• Replace worn-out gaskets and seals.

? Check Gaskets & Fasteners:

• Replace if brittle, cracked, or compressed beyond limits.

Download Handbook: Handbook of plate heat exchangers

5. Reassembly & Testing:

? Reassemble Components:

• Insert cleaned/repaired tube bundle or plates.
• Apply new gaskets and reassemble covers with proper torque.

? Pressure Testing:

• Perform hydrostatic testing (pressurize with water to check for leaks).
• Conduct pneumatic testing (if required, using compressed air and soap solution).

? Final Checks:

• Ensure all bolts are tightened to spec.
• Verify proper alignment of connections.

6. Commissioning & Restarting:

? Gradual Startup:

• Open isolation valves slowly.
• Monitor for leaks or abnormal vibrations.

? Performance Monitoring:

• Check inlet/outlet temperatures, flow rates, and pressure drops.
• Ensure efficiency is restored to expected levels.

Conclusion:

A well-executed heat exchanger overhaul improves efficiency, prevents costly failures, and extends operational life. Regular maintenance schedules help minimize downtime and enhance reliability.

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