Tube Bundle Cleaning: Methods & Best Practices

When to Clean

Schedule tube cleaning when:

• The overall heat transfer coefficient (U-value) drops to 70% of the clean/design value
• The pressure drop across the exchanger increases by 50% above the clean baseline
• The approach temperature (difference between hot outlet and cold inlet) increases significantly
• During annual planned shutdowns (for critical service)
• After a process upset that may have introduced contamination

Preparation

1. Isolate: Close inlet and outlet valves on both shell and tube sides. Lock out and tag out.
2. Drain: Drain all fluid from both sides. Collect process fluids for proper disposal.
3. vent: Open vent valves to break any vacuum and ensure complete draining.
4. Remove bonnet/channel covers: Remove the tube-side bonnet or channel cover to access the tube sheet.
5. Inspect the tube sheet: Look for signs of corrosion, galling, or tube-to-tube-sheet joint leakage before cleaning.

Cleaning Methods

• Mechanical brushing: A rotating nylon or brass brush is pushed through each tube. Effective for soft deposits (sludge, biological growth, light scale). The brush size must match the tube internal diameter. Low cost, but labour-intensive for large bundles.
• High-pressure water jetting (hydroblasting): Water at 5,000–20,000 psi is directed through the tubes using a self-advancing lance. Effective for hard scale and stubborn deposits. Must be done carefully — excessive pressure can damage thin-walled tubes. The lance must be kept moving to avoid cutting through the tube wall.
• Chemical cleaning (CIP): A cleaning solution (acid for mineral scale, alkali for organics, biocide for biological) is circulated through the exchanger without removing the bundle. Effective for light to moderate fouling. Requires compatible materials and thorough rinsing afterwards.
• Explosive cleaning (detubing): A small explosive charge is detonated inside each tube, shattering hard deposits. Used for severe scale that can't be removed by other methods. Requires specialist contractors and safety procedures.
• Pigging: A cleaning 'pig' (a cylindrical scraper) is pushed through the tubes by water pressure. Removes soft deposits. Not suitable for hardened scale.

Choosing the Right Method

Post-Cleaning

• Inspect each tube internally using a borescope — look for thinning, pitting, or cracking
• Conduct a hydrostatic pressure test at 1.5× design pressure to verify tube integrity
• Plug any tubes that are leaking or excessively thinned (don't plug more than 10% of tubes — if more are damaged, retube the bundle)
• Reinstall the bonnet/channel cover with a new gasket
• Record the before and after U-value and pressure drop for trend comparison