Bundle Cleaning: The Complete Guide to Tube Bundle Maintenance

Bundle Cleaning: Methods, Maintenance Schedules, and Industry Best Practices

A fouled tube bundle simply doesn’t warn you with alarms or buzzer lights. It warns you through higher energy bills, increased unplanned shutdowns that cost tens of thousands per hour, and dramatically reduced throughput leading to missed deadlines and lost revenues. The Bundle cleaning is the single most effective maintenance procedure to regain shelland-tube heat transfer effectiveness – yet many refineries and chemical plants still time cleaning either to fall too early, wasting development time and money, or too late, after efficiency has long since dropped to within a percent or two of the line losses.

This guide runs through the specific techniques, pressure window selections, interval triggers, and costing details you need to schedule bundle cleaning properly, whether maintaining a refinery crude-pre-heat train, a petrochemical reactor effluent cooler, or a power station condenser.

What Is Bundle Cleaning in Industrial Heat Exchangers?

Bundle cleaning is the removal of fouling deposits — scale, coke, biological growth, rust, dirt, and grime — from the inside (tube-side) and outside (shell-side) of tube bundles in shell-and-tube heat exchangers, restoring design-level heat transfer performance.

All shell-and-tube heat exchangers have a tube bundle: a group of tubes with tube sheets holding them in position and tubes supported by baffles. Fouling deposits occur on the tube-surfaces as well as on the shell-surfaces as a result of entrainment and of fouling characteristics of the fluids (Polasek, 1972). The ensuing fouling which occurs on the tube-surfaces is refered to collectively as fouling.

It acts as an isolator to of heat transfer between the hot and cold streams. Operationally the effect of the fouling means that operator will have to increase flow rates, inlet streams temperatures, or accept the reduction of output.

Costs are immense. Using the Ipieca Energy Efficiency Compendium for Heat Exchangers (2022), one 100,000 bbl/day refinery may see heat loss due to fouling of about $31.17 million a year. A fouled bundles generally experience a 20-30% reduction in thermal efficiency 12-18 months after being put into service, depending on the service and fluid properties.

Annual bundle cleaning, carried out at the right intervals with the right method, is not optional — it is essential for heat exchanger asset management. Cleaning systems have made great advances in the last 20 years, from manual rodding to modern, computer-controlled, high-pressure water jetters that can return a bundle to near-original thermal performance.

TEMA (Tubular Exchanger Manufacturers Association) Standards specify the mechanical design considerations including tube material, wall thickness and baffle arrangements that determine where and when the bundles should be cleaned.

Common Types of Fouling That Demand Bundle Cleaning

Different kinds of fouling exist. Each type of deposit provides a specific cleaning procedure, and the pressure at which it has to be executed as well as the associated cost. These are the five fouling types of industrial heat exchangers:

Proper filter installation on inlet lines and zero back-pressure during testing are requirements before any cleaning attempt. Be aware that open-loop cooling water plants regularly experience biological fouling, increased particulate accumulation, and loosely adherent deposits, while crude pre-heat exchangers generally develop dense asphaltene deposits and corrosion products. Most petrochemical maintenance scenarios involve chemical reaction fouling (coking, polymerization) that demands the most aggressive cleaning treatment.

Bundle Cleaning Methods — ID and OD Techniques Compared

Bundle cleaning methods split into two categories based on which surface is being cleaned. ID cleaning (tube-side) focuses on the interior of the tubes where the process fluid passes through; OD cleaning targets the outside of the tube surfaces and the shell-side spaces between tubes. Combined ID and OD cleaning is common in turnaround maintenance.

Water jetting has an associated per tube cleaning cost of US0.50-2 for water jetting, versus an overall chemical cleaning cost of US5-15, a 30-50% improvement over chemical alone when water jetting is possible. Chemical cleaning cannot be replaced with water jetting in the removal of certain fouling types such as tight CaCO3 scale in small-bore tubes under 12 mm ID.

Capital investment for automated bundle cleaning equipment ranges from €50,000 to €200,000 depending on pump capacity, automation level, and whether the system is trailer-mounted for field service or fixed in a cleaning shop.

Step-by-Step Bundle Cleaning Process

The standard sequence for bundle cleaning whether on or off site involves a number of steps, skipping any of which can lead to costly errors.

1. Isolation and lock-out-the step before cleaning; depressurize while removing pressures through locking open inlet and outlet valves; segregate residual fluids; verify zero-energy condition using lockout/tagout (LOTO) procedures according to the plants operating procedures. Confirm no residual pressure exists between isolation valves.
2. Bundle removal-Any of the major types of hydraulic bundle extractors, with capacity from 5 to 25+ tons pulling force can be used. Heavy-duty equipment is available to locate and pull bundles up to 78″ diameter by 26 ft length. Larger locations are matched with diesel-powered bundle puller equipment that generates sufficient force without an external power source.
3. Pre-cleaning inspection-Document all tube anomalies with photographs, to locate plugs or corrosion markers; record tube UT wall measurements at a minimum of three points per tube; identify fouling deposits, noting any pinholed or severely corroded tubes.
4. Tube-side (ID) cleaning-Insert high-pressure (1,000+ bar) lances or rotating nozzles from the tube sheet face. Work the bundle systematically from top to bottom in sequential rows, cleaning tube-by-tube, to prevent debris from resettling on already-cleaned surfaces.
5. Shell side (OD) cleaning – Position the bundle in a wash bay or on a cleaning rack. Use external jetting at 500-1,500 bar, working from one end of the tube bundle to the other. Focus on baffle cut areas known to accumulate more deposits.
6. Post-cleaning tube inspection & hydrostatic test – Conduct a visual and UT inspection of tube surfaces where wall thinning was detected. Conduct a hydrostatic test according to ASME Section VIII Div. 1 (test pressure = 1.3 × design pressure). Detect any leaking tubes and plug them.
7. Bundle re-installation – Use guide rails or roller supports to align the bundle with the shell bore. Apply an anti-seize compound to gasket surfaces, fit new gaskets, and torque flange bolts per the manufacturer specifications using a calibrated torque wrench in a star pattern.

Pre-Cleaning Inspection Checklist

• ✔Verify zero-energy state (LOTO complete)
• ✔Record inlet/outlet temperatures and pressures before shutdown
• Conduct UT of tube walls at least 3+ locations per tube (initial wall thickness baseline)
• ✔Photograph fouling patterns before cleaning
• Specify makeup water volume and pressure of your cleaning water supply.
• Review tube material and maximum allowable cleaning pressure.

Bundle Cleaning Frequency and Maintenance Planning

How often should tube bundles be cleaned? No single answer fits every plant. Frequency of cleaning is influenced by the service, fluid characteristics, heat exchanger configuration, and – most importantly – measurable performance indicators.

According to TEMA Appendix E maintenance schedule principles, clean the bundle when the OHTC falls 15-25% below its design level or when the cost of energy loss surpasses the cost of a maintenance shutdown. This cost-based decision model ensures you avoid both premature and excessively late cleaning events.

Crude pre-heat train exchangers in oil refineries present extreme fouling challenges. Asphaltene-based fouling tends to accelerate over time non-linearly – the last 20% of the initial available thermodynamic efficiency can be lost in just a third of the operating time it took to lose the first 20%. Tracking temperature approach weekly and trend OHTC monthly gives maintenance planning a year’s worth of lead time to include the cleaning event in existing turnaround schedules rather than bunching it with emergency shutdowns.

Eager to put a dollar figure on the difference between waiting too long and cleaning too early? Access our turnaround downtime cost calculator and compare it to the energy drain of continued fouled operation. For equipment recommendations, look into bundle cleaning solutions sized for your operation.

Choosing Between In-Situ and Ex-Situ Bundle Cleaning

Choosing whether to clean in situ or ex situ is one of the first major decisions in a bundle cleaning job. There are advantages and disadvantages to both.

In-Situ Cleaning

Ex-Situ Cleaning

TEMA type designations dictate the options you have. Float-head types (AES, AET, AEP) permit full removal of the bundle for ex-situ cleaning – the float-head cover and shell cover are stripped, and the bundle slides out on rails or is drawn out with an extractor. Fixed tubesheet types (AEL, AEM, AEN) have their tubes welded permanently to both tube sheets, and present no opportunity to remove the bundle. Only in-situ, tube-side cleaning is feasible.

Decide between approaches by balancing fouling severity with turnaround expense. Mild particulate fouling on the tube side may be cleared in a single day with an in-situ water jetting job. Heavy carbon deposits both ID and OD surfaces warrant the 3-5 day ex-situ approach because cleaning only the tube side will leave the shell-side deposits unchecked.

If you do not own an extractor equipment, you may choose from equipment rental options to meet your project’s requirements. For permanent installations or frequent turnaround cycles, a self-propelled bundle extractor cuts the need for cranes and can perform cleaning up to 40% faster than manual pull methods.

Frequently Asked Questions About Bundle Cleaning