1. What Is Re-Tubing?
Re-tubing is the process of replacing all (or a large portion of) the tubes in a shell-and-tube heat exchanger, condenser or boiler. Over years of service, tubes corrode, erode, crack and thin until they can no longer perform safely — but the shell, tube sheets and other components remain sound. Re-tubing restores the heat exchanger to like-new condition by fitting a complete set of new tubes, at a fraction of the cost of a whole new unit.
Re-tubing is a systematic, multi-step process that ties together several specialist tools and techniques — tube removal, tube sheet repair, tube installation, expansion, welding and testing. This guide walks through the complete process step by step, showing how each stage and each tool fits together.
Re-Tubing: Economical Restoration
A heat exchanger shell and tube sheets can last decades, but tubes wear out faster. Re-tubing — replacing just the tubes — restores the unit to like-new condition for a fraction of the cost of a complete replacement, while reusing the expensive shell and tube sheets. It's one of the most cost-effective maintenance strategies for extending heat exchanger life, and it requires a coordinated set of tools that Shingare Industries supplies as a complete toolkit.
2. When to Re-Tube
A heat exchanger is due for re-tubing when:
- Multiple tube failures: Tubes are leaking or failing faster than plugging can economically manage.
- Plugged-tube limit reached: The number of plugged tubes approaches the ~10% design limit, reducing capacity too much.
- Widespread thinning: Inspection shows tube walls thinned by corrosion or erosion across the bundle.
- End of service life: The tube bundle has reached the end of its expected service life.
- Efficiency loss: Fouling and tube degradation have reduced performance beyond what cleaning can restore.
3. Planning the Re-Tube
Before starting, a re-tube must be planned: new tubes ordered to the correct material, diameter, wall thickness and length; the tube sheet condition assessed to anticipate repair needs; all tools gathered (removal, repair, expansion, welding and testing equipment); the shutdown scheduled and the heat exchanger isolated, drained, cooled and decontaminated; and safety measures (permits, confined space, PPE) put in place. Good planning ensures the re-tube proceeds smoothly within the shutdown window.
4. Step 1: Remove Old Tubes
The first step is removing the old tubes without damaging the reusable tube sheet:
- Remove seal welds (if tubes are welded) by grinding or machining.
- Internal cut: An internal pipe cutter severs each tube just inside the tube sheet, freeing the main tube length.
- Pull the tubes/stubs: A tube puller extracts the main tube lengths and the remaining stubs from the tube sheet.
Cutting the tube internally before pulling protects the tube sheet holes, which must accept the new tubes. (See our dedicated internal pipe cutter and tube puller guide for detail.)
Protect the Tube Sheet During Removal
The tube sheet is reused, so it must survive tube removal undamaged. The internal-cut-then-pull method — severing each tube inside the tube sheet, then extracting the stub — removes old tubes while preserving the tube sheet holes. This is far safer than trying to drive out intact expanded tubes, which risks tearing the tube sheet holes.
5. Step 2: Repair the Tube Sheet
With the old tubes out, the tube sheet is cleaned, inspected and repaired:
- Clean the tube holes of old tube remnants, corrosion and debris — new tubes can't seal against dirty holes.
- Inspect each hole for corrosion, scoring, roundness and diameter.
- Re-cut grooves that have corroded away, restoring joint grip.
- Face corroded or uneven tube sheet surfaces flat.
- Recondition gasket surfaces for leak-tight flange joints.
(See our dedicated tube sheet repair guide for detail.) A well-prepared tube sheet is essential for reliable new joints.
6. Step 3: Install New Tubes
The new tubes — cut to the correct length and deburred — are inserted through the baffles and into the tube sheet holes at both ends. The tubes must be positioned with the correct projection beyond each tube sheet. Care is taken to insert tubes without scratching them and to seat them correctly through the baffle support plates. With hundreds or thousands of tubes, this is methodical work, but straightforward with the tubes and tube sheet correctly prepared.
7. Step 4: Expand the Tubes
Each new tube is then expanded into the tube sheet using a tube expander — the critical joint-forming step. A torque-controlled roller expander (or hydraulic expander) expands each tube uniformly against the tube sheet hole, with the tube metal flowing into the grooves to grip firmly, achieving the correct wall reduction for a leak-tight, strong joint.
Consistent, controlled expansion of every tube is essential — this is where torque control ensures every joint is expanded identically and correctly. (See our tube expander selection guide for detail.)
Expansion Is the Critical Joint-Forming Step
Tube expansion creates the actual seal and grip of every tube joint — it is the make-or-break step of the re-tube. Torque-controlled expansion ensures every one of the hundreds or thousands of joints is expanded to the correct, consistent degree, producing uniformly leak-tight joints. This is why quality tube expanders and torque-controlled drives are central to a successful re-tube.
8. Step 5: Weld (if required)
For higher-pressure, critical or code-required service, the new tubes are seal-welded to the tube sheet in addition to being expanded. Tube-to-tubesheet welding provides an additional, permanent leak-tight seal. The welding sequence and technique follow the applicable code and welding procedure specification. Not all heat exchangers require welding — many rely on expansion alone — but where welding is specified, it is done after (or in a defined sequence with) expansion.
9. Step 6: Test the Joints
Finally, the re-tubed heat exchanger is tested to verify every joint is leak-tight before returning to service:
- Hydrostatic test: The unit is pressurised with water to test all joints for leaks and to prove pressure integrity.
- Pneumatic/leak test: Air or other leak-testing methods to detect any remaining leaks.
- Rectify: Any leaking joints are re-expanded, re-welded or (if necessary) plugged.
Only after passing the test is the re-tubed heat exchanger returned to service — restored to reliable, leak-tight, like-new condition.
10. The Complete Re-Tubing Toolkit
Re-tubing requires a coordinated set of tools across all six steps — which Shingare Industries supplies as a complete ISO 9001 certified toolkit:
| Step | Tools Required |
|---|---|
| 1. Remove old tubes | Internal pipe cutters, tube pullers |
| 2. Repair tube sheet | Hole cleaners, grooving tools, facing tools |
| 3. Install new tubes | New tubes, deburring tools |
| 4. Expand tubes | Tube expanders + torque-controlled drives |
| 5. Weld (if required) | Welding equipment (per code) |
| 6. Test | Hydrostatic/pressure test equipment; tube plugs for rectification |
Supplying the whole toolkit from one source ensures compatible, quality-matched tools for the complete re-tube.
This article is general technical guidance. Re-tubing — especially of boilers and pressure equipment — must follow applicable codes (e.g. IBR for boilers in India), manufacturer specifications and site safety procedures, performed by competent, authorised personnel.
Frequently Asked Questions
Re-tubing is replacing all (or a large portion of) the tubes in a shell-and-tube heat exchanger, condenser or boiler while reusing the shell and tube sheets. Over years of service, tubes corrode, erode, crack and thin until they can't perform safely, but the shell and tube sheets remain sound — so re-tubing restores the unit to like-new condition at a fraction of the cost of a whole new heat exchanger. Re-tubing is needed when: multiple tubes are failing faster than plugging can manage; the plugged-tube count approaches the ~10% design limit; inspection shows widespread tube wall thinning; the bundle has reached end of life; or performance has degraded beyond what cleaning can restore.
Re-tubing has six main steps: (1) Remove old tubes — remove any seal welds, then use an internal pipe cutter to sever each tube inside the tube sheet and a tube puller to extract the tubes and stubs, protecting the reusable tube sheet; (2) Repair the tube sheet — clean and inspect the tube holes, re-cut worn grooves, face corroded surfaces and recondition gasket surfaces; (3) Install new tubes — insert new tubes through baffles into the tube sheet holes with correct projection; (4) Expand the tubes — use torque-controlled tube expanders to expand each tube into the tube sheet, the critical joint-forming step; (5) Weld if required — seal-weld tubes to the tube sheet for high-pressure or code-required service; (6) Test — hydrostatic and leak testing to verify every joint before returning to service.
A heat exchanger's shell and tube sheets are its most expensive, long-lived components and can last decades, but the tubes wear out faster through corrosion, erosion and cracking. Re-tubing replaces only the tubes while reusing the sound shell and tube sheets, so it restores the unit to like-new condition for a fraction of the cost of manufacturing and installing a complete new heat exchanger. This makes re-tubing one of the most cost-effective maintenance strategies for extending heat exchanger service life. It requires a coordinated set of specialist tools (removal, tube sheet repair, expansion, testing) which Shingare Industries supplies as a complete toolkit.
Tube expansion (step 4) is the critical joint-forming step — it creates the actual seal and grip of every tube-to-tubesheet joint, making it the make-or-break stage of the re-tube. Each new tube is expanded into the tube sheet with a tube expander, with the tube metal pressed against the hole wall (and flowing into grooves) to achieve the correct wall reduction for a leak-tight, strong joint. Because a heat exchanger has hundreds or thousands of joints, each a potential leak, consistent controlled expansion is essential — which is why torque-controlled expanders that expand every tube identically and correctly are central to a successful re-tube. Proper tube sheet preparation (step 2) is equally important as its foundation.
A complete re-tube needs a coordinated toolkit across all six steps: internal pipe cutters and tube pullers for removing old tubes; tube hole cleaners, grooving tools and facing tools for tube sheet repair; new tubes and deburring tools for installation; tube expanders with torque-controlled drives for expansion; welding equipment (per code) where tube-to-tubesheet welding is required; and hydrostatic/pressure test equipment plus tube plugs for testing and rectifying any leaking joints. Shingare Industries supplies this entire toolkit as a single ISO 9001 certified source, ensuring compatible, quality-matched tools for the complete re-tube — from tube removal through to the final leak test.