Repair, re-tube, recore or replace heat exchangers of any make, including obsolete units with no drawings. The engineering is done by AMI Exchangers in the UK, with Petromarsh service engineers on site in the GCC.
Tap a part to see what it does. A removable bundle is lifted out of its shell, inspected, and then plugged, re-tubed or replaced. The circle shows the tubesheet face.
Lifting beam and slings. The bundle is drawn out with a bundle extractor or a crane and spreader beam, supported along its length so the tubes and baffles are not bent.
Tube bundle. Tubes, baffles and tie rods. Once out of the shell, the outside of the tubes can be cleaned and inspected, and wall loss measured tube by tube.
Tubesheet. Checked for corrosion, cracking and enlarged tube holes. If the ligaments between holes are sound, it can be reused for a re-tube.
Plugged tubes. Leaking or badly thinned tubes are sealed at both ends with tapered plugs. Each plug takes surface out of service, so the count is tracked.
New tubes. In a re-tube the old tubes are cut out and new ones are expanded or welded into the same tubesheets, often in a better material.
Shell. Stays in place with the piping connected. It is inspected for wall thickness and nozzle condition while the bundle is out.
Most exchangers do not wear out all at once. Tubes thin from corrosion and erosion, fouling cuts performance, and joints start to leak. An inspection shows which parts are worn, so you only renew what you need.
A pressure or leak test on the shell side shows which tubes leak. Eddy current testing measures wall loss in every tube, so you can see how many more are close to failing.
A few bad tubes can be plugged. Wall loss across the bundle means a re-tube or a new bundle. If the shell and channel are also worn, or the design no longer suits the duty, full replacement is better.
When the original maker has gone or no drawings exist, the unit is measured and redrawn. The new part fits the existing nozzles, supports and pipework.
The right repair depends on how much of the unit is worn and why. Start with the smallest fix that solves the cause, and step up only when the inspection says so.
Tapered plugs are driven or welded into both ends of each leaking tube. It is quick and low cost and can often be done in a short shutdown.
Seawater coolers with a handful of pitted or eroded tubes.
The old tubes are cut out and new ones are fitted and expanded or welded into the original tubesheets. The shell, baffles and tubesheets are kept if they pass inspection.
Condensers and coolers where the tubes have reached the end of their life.
A new bundle with tubes, tubesheets, baffles and tie rods, built to fit the existing shell. It is the usual choice for floating-head and U-tube exchangers.
Refinery exchangers with removable bundles in fouling service.
In charge air coolers, oil coolers and other compact coolers, the tubes, fins and tubesheets form one core. Recoring replaces that core inside the existing casing, headers or water boxes.
Engine charge air coolers and motor coolers.
A complete new unit, designed to match the old one's nozzles, supports and performance, or improved for the current duty. For obsolete units without drawings, the old unit is measured on site.
Units from makers that no longer exist or no longer support them.
Use the repair to remove the cause: a better tube material, an impingement plate, a different baffle layout or extra surface for a higher duty. A thermal check confirms the new design.
Coolers that see warmer seawater or higher loads than they were designed for.
If tubes failed from corrosion or erosion, putting back the same material buys the same life. These are common upgrades when re-tubing or building a new bundle.
| Part | Often found | Common upgrade | Why |
|---|---|---|---|
| Seawater tubes | Admiralty or aluminium brassSB-111 C44300 · C68700 | Copper-nickel 90/10 or 70/30, or titaniumSB-111 C70600 · C71500 · SB-338 | Better resistance to erosion, polluted water and chlorides |
| Cooling water tubes | Carbon steelSA-179 · SA-214 | Stainless 316L or duplex 2205SA-213 · SA-789 | Stops pitting and under-deposit corrosion |
| Tubesheets | Carbon steel or naval brassSA-516 · SB-171 | Clad with the tube material, or solid alloyexplosion bonded | Matches the new tubes and avoids galvanic attack |
| Joints | New gaskets every time a joint is opened, and bolts tightened to a controlled procedureASME B16.20 · PCC-1 | ||
Repairs follow the code the unit was built to, plus your inspection procedures and company specification.
Pressure vessel inspection code: inspection, repair, alteration and rerating of vessels in service.
Inspection practices for pressure vessels, including heat exchangers.
Damage mechanisms affecting fixed equipment, used to find why a unit failed.
Repair of pressure equipment and piping, including tube plugging methods.
Assembly of bolted flange joints, for leak-free reassembly after repair.
Eddy current testing of non-magnetic tubes, and remote field testing of steel tubes in place.
New bundles and parts are built to the original code, or to the current edition if you specify it.
Qualified welding procedures and welders for tube-to-tubesheet and pressure welds.
Certified mill certificates for every new tube, tubesheet and pressure part.
We inspect first and compare the options. Your engineers red-line the scope and approve it before work starts, and you can witness the tests. Tap a step to see what happens and which documents you receive.
AMI Exchangers repairs, recores and re-tubes heat exchangers of any make, and identifies and rebuilds units that have no drawings. They have completed more than 25,000 projects. Petromarsh is their exclusive representative in the GCC, with service engineers on site.
Photos of the nameplate and the damage are often enough for a first answer on repair or replacement. Add the items on the right if you have them.
