Heat exchangers foul, corrode and leak, and most of the work needed to restore them can only be done with the unit offline. That makes exchanger work one of the largest and most frequent parts of any refinery or petrochemical turnaround, and exchangers often sit on or near the critical path. Heat exchanger maintenance during turnarounds is a chain of steps involving several trades and specialist contractors, heavy lifts and inspection decisions. Here is how the work is done and what planners need to get right, for maintenance managers, turnaround planners and supervisors.
What does heat exchanger maintenance in a turnaround involve?
It involves isolating and opening the exchanger, removing and cleaning the tube bundle where the design allows, inspecting tubes, tubesheets and shell, carrying out repairs, then reassembling, testing and returning the exchanger to service with complete records.
Exchanger types and what the work looks like
| Type | Typical turnaround work |
|---|---|
| Shell-and-tube, floating head | Remove channel and floating head, extract bundle, clean shell and tube sides, inspect, repair, reassemble |
| Shell-and-tube, U-tube | Extract bundle, clean, inspect; tube-side cleaning of the bends needs suitable methods |
| Shell-and-tube, fixed tubesheet | Bundle cannot be removed; clean tube side in place, inspect, repair from the channel side |
| Air-cooled exchangers | Open header plugs or covers, clean tubes and fins, check fans, motors and drives |
| Plate exchangers | Open the frame, clean and inspect plates, replace gaskets, reassemble to the correct dimension |
The work sequence
- Isolate, drain, purge and depressurize both sides, with blinds installed and recorded.
- Remove covers and heads, such as the channel cover, channel and shell cover.
- Extract the bundle with a bundle extractor or crane, where the design allows.
- Clean by high-pressure water jetting, chemical cleaning or mechanical methods, depending on the fouling.
- Inspect tubes, tubesheets, baffles and shell. Tube inspection commonly uses eddy current testing for non-ferrous tubes and IRIS or remote field testing for ferrous tubes.
- Repair by plugging leaking or thinned tubes within agreed limits, retubing or replacing the bundle where necessary, and repairing gasket faces.
- Reassemble with new gaskets and controlled bolting.
- Test the shell and tube sides, usually by hydrotest, and check for leaks.
- Box up, remove blinds under control, reinstate insulation and hand back.
Planning points that keep exchangers on schedule
- Space: laydown and a cleaning pad large enough for bundles, with drainage for jetting water
- Equipment: bundle extractors, cranes and jetting units booked in a central schedule
- Spares: replacement bundles for exchangers likely to need them, ordered well before the shutdown
- Materials: gasket and bolt kits for every joint, labeled by exchanger
- Repair limits: tube plugging limits agreed with engineering in advance, so decisions are fast
- Inspection coverage: inspectors available when bundles come off the cleaning pad
- Waste: handling of jetting water, sludge and deposits, including pyrophoric material
Exchanger jobs pass through several contractors: scaffolding, insulation, mechanical, cleaning specialists and inspection. The handover chain is set out in contractor coordination during plant turnarounds.
Safety points specific to exchanger work
High-pressure water jetting needs trained operators, operator-controlled dump systems and exclusion zones. Bundle lifts are heavy and awkward, so they need lift plans and competent riggers. Deposits from sulfur-containing services can be pyrophoric and must be kept wet. The wider turnaround safety controls are covered in turnaround safety management for high-risk work.
Records
Each exchanger should have a completed record: as-found condition, cleaning method, inspection results, tubes plugged and their locations, repairs, gasket and bolting details, test results and sign-offs. These records support future inspection planning and are part of the quality controls described in inspection and quality controls during shutdown maintenance. The work pack that carries all of this is described in mechanical work packages during plant shutdowns.
Apex Core Engineering supplies mechanical crews, riggers and supervisors for exchanger work during shutdowns through its skilled manpower supply service.
Frequently asked questions
Why are exchangers often on the turnaround critical path?
Because the sequence of opening, cleaning, inspection, repair, reassembly and testing is long, depends on shared equipment and specialist contractors, and can grow when inspection finds damage.
What is tube plugging?
Sealing both ends of a leaking or thinned tube so it is taken out of service. It is allowed only within limits set by engineering, because plugged tubes reduce exchanger performance.
How are exchanger tubes inspected?
Commonly with eddy current testing for non-ferrous tubes and IRIS or remote field testing for ferrous tubes, plus visual inspection of tubesheets and accessible surfaces.
Get support for turnaround exchanger work from Apex Core Engineering.