Fouling: Why Heat Exchangers Need Cleaning
Deposits on heat transfer surfaces are called fouling. Scale, sludge, corrosion products, polymers and product residue conduct heat far worse than the tube material: boiler scale, depending on its structure, ranges from about 0.1 to 2 W/(m·K) (0.06 to 1.2 Btu/(h·ft·°F)), carbon steel is about 50 W/(m·K) (29 Btu/(h·ft·°F)). The layer acts as insulation. Heat transfer drops, and the plant needs more heating or cooling duty for the same process temperature.
The deposit also narrows the tube cross-section, and pressure drop across the unit rises. In operation, fouling shows up as rising pressure drop between inlet and outlet, a falling temperature difference on the process side and higher energy consumption per ton of product. For sizing the cleaning pump, the type of deposit matters most, because it sets the required pressure.
Cleaning Methods and What the Pump Has to Deliver
Cleaning usually takes place on the opened unit: the channel head or bonnet is removed to expose the tube ends in the tubesheet, or the bundle is pulled to clean the shell side. Each method places its own demands on the pressure side.
Tube-Side Cleaning
For tube-side cleaning, a lance travels through each individual tube. Rigid lances suit straight tubes; flex lances, built on high-pressure hose, also follow U-tubes and run off a high-pressure hose reel. The nozzle at the lance tip is matched to the tube inside diameter: forward jets open plugged tubes, side and rear jets clean the tube wall. Rotating nozzles distribute the jet evenly around the circumference.
For the pump, this means high pressure at a comparatively low flow rate per lance, and fast pressure adjustment when tubes with different deposits follow each other.
Shell Side and Plate Packs
The shell side of a pulled bundle is cleaned from the outside with high-pressure lances that direct the jet between the tube rows. Plate heat exchangers are taken apart and the plates cleaned individually with high-pressure guns or surface cleaners. On air coolers, pressure is matched to the strength of the fins.
Here the jet covers larger areas, so higher flow rates at moderate pressure are required.
Hand-Held, Mechanically Guided or Automated
Hand-held lances are common on small units and individual tubes. Mechanical lance feeders and multi-lance machines clean several tubes at once, keep feed rate and dwell time constant and cut cleaning time per bundle. The operator controls the process from outside the jetting zone. For the pump, this means higher flow and continuous duty over the full shift. KAMAT units are designed for this continuous duty with semi-automatic and fully automatic tools.
Selecting Pressure and Flow Rate
| Deposit | Typical pressure range |
|---|---|
| Sludge, loose product residue, biofilm | 300 to 1,000 bar (4,350 to 14,500 psi) |
| Scale, corrosion products, medium-hard deposits | around 1,000 bar (14,500 psi), the typical operating point |
| Hard scale and silicate deposits, coke, polymers | 2,500 bar (36,250 psi) and above, up to 4,000 bar (58,000 psi) |
Operating pressure follows the adhesion of the deposit; flow rate follows the number of lances and the required cleaning speed. Cleaning takes place above the adhesion limit of the deposit and below the damage threshold of the base material. Because KAMAT pumps are continuously variable, this window can be hit precisely, even on thin-walled tubes and copper alloys
Reaction Force Limits the Flow Rate per Hand-Held Lance
Whether a lance may be hand-held is decided by the reaction force at the tool. It follows F = Q · √(2 · ρ · Δp): flow rate enters linearly, pressure sits under the square root. Doubling the flow doubles the reaction force; doubling the pressure raises it by 41 percent.
The UK Water Jetting Association’s Code of Practice caps reaction force on hand-held equipment at 250 N (56 lbf) in the longitudinal direction. German DGUV Rule 100-500, Chapter 2.36 sets the same limit and requires additional measures above 150 N (34 lbf), such as a body support, a foot switch or a force-absorbing holder. In the United States there is no OSHA standard for high-pressure water jetting; the WJTA-IMCA Recommended Practices are the voluntary reference. Where no rule applies, 250 N is still the practical limit of what an operator can hold through a shift. The maximum flow per hand-held lance follows from it:
For pump sizing, this means the number of lances running at the same time sets the flow rate. Anyone who wants to supply more than one hand-held lance, or needs more flow per tool, works with a mechanical lance feeder or a multi-lance machine. The Nozzle Calculator works out the operating point for nozzle, lance and pump.
| Operating pressure | Flow rate at 250 N (56 lbf) |
|---|---|
| 1,000 bar (14,500 psi) | approx. 34 l/min (9.0 gpm) |
| 2,000 bar (29,000 psi) | approx. 24 l/min (6.3 gpm) |
| 3,000 bar (43,500 psi) | approx. 19 l/min (5.0 gpm) |
Pump Selection from the Performance List
The table shows two operating points at rated power for each series, taken from the KAMAT performance list: one for the typical operating point around 1,000 bar and one for hard deposits from 2,500 bar
| Series | Drive power | Operating point around 1,000 bar | Hard deposits from 2,500 bar |
|---|---|---|---|
| K5500-3 | 55 kW (74 hp) | 25 l/min (6.6 gpm) at 1,140 bar (16,550 psi) | 11 l/min (2.9 gpm) at 2,565 bar (37,200 psi) |
| K9000-3G | 90 kW (121 hp) | 37 l/min (9.8 gpm) at 1,130 bar (16,400 psi) | 13 l/min (3.4 gpm) at 3,140 bar (45,550 psi) |
| K11000-3G | 110 kW (148 hp) | 52 l/min (13.7 gpm) at 1,080 bar (15,650 psi) | 21 l/min (5.5 gpm) at 2,665 bar (38,650 psi) |
| K18000-3G | 180 kW (241 hp) | 84 l/min (22.2 gpm) at 1,130 bar (16,400 psi) | 32 l/min (8.5 gpm) at 2,985 bar (43,300 psi) |
| K25000-3G | 250 kW (335 hp) | 130 l/min (34.3 gpm) at 1,010 bar (14,650 psi) | 51 l/min (13.5 gpm) at 2,580 bar (37,400 psi) |
| K45000-3G | 450 kW (603 hp) | 232 l/min (61.3 gpm) at 1,030 bar (14,950 psi) | 84 l/min (22.2 gpm) at 2,855 bar (41,400 psi) |
| K55000-5G | 550 kW (738 hp) | 275 l/min (72.6 gpm) at 1,060 bar (15,350 psi) | 103 l/min (27.2 gpm) at 2,840 bar (41,200 psi) |
Two examples: with 55 kW (74 hp), the K5500-3 delivers 25 l/min (6.6 gpm) at 1,140 bar (16,550 psi) and supplies one hand-held lance. Reaction force is then about 200 N (45 lbf), below the 250 N limit but above 150 N, so a body support or force-absorbing holder is needed. With 250 kW (335 hp), the K25000-3G delivers 130 l/min (34.3 gpm) at 1,010 bar (14,650 psi). At the 250 N limit, three hand-held lances together need about 100 l/min (26.4 gpm); the pump is turned down to about 77% of rated flow for this. At full flow it supplies a multi-lance machine. As in the performance list, the figures assume 100% volumetric efficiency and 20 °C (68 °F) ambient temperature.
As mobile units, the K18000-3G, K25000-3G, K45000-3G and K55000-5G are also available as KAMJET units (KAMJET 180T, 250, 450 and 550). For jobs with short lead times, KAMAT keeps pumps and units available now. All operating points are listed in the KAMAT Pump Performance List.
Closed-Loop Water and Filtration
High-pressure water cleaning needs no chemicals. No pickling agent remains in the process equipment, and there is no chemically contaminated wastewater that has to be neutralized. Seals and base material are not attacked chemically.
The removed residue is collected with the jetting water and separated. With filtration, the water can run in a closed loop, which reduces fresh water demand and disposal volume per cleaning cycle. For closed-loop operation, KAMAT supplies high-pressure filters that keep particles from the recirculated water away from nozzles and tools, and suction stabilizers that steady the pump inlet flow and prevent cavitation. Whether the jetting water may be discharged, and at what limits, is set by the permitting authority or the receiving utility.
Safety Equipment from Pump to Lance
In the United States, the WJTA-IMCA Recommended Practices are the voluntary industry reference for high-pressure water jetting; there is no OSHA standard specific to it. In the United Kingdom, the Water Jetting Association Codes of Practice apply, in Germany the DGUV Rule 100-500, Chapter 2.36. In Europe, EN 1829-1 sets the safety requirements for high-pressure water jet machines.
Tube cleaning adds two points. The lance must depressurize as soon as the operator releases the control. When it is withdrawn, the lance must not exit the tube uncontrolled. KAMAT supplies the valve technology for this: foot valves for dump control at the work position, safety valves against impermissible pressure build-up and multi-user valves for running several lances on one pump
Where KAMAT Cleaning Units Work
These industries are typical applications. Requirements on the pressure side differ with the deposit and the turnaround schedule:
- In refineries and the oil and gas industry, shell-and-tube heat exchangers coke up in the hot preheat trains, while hydrocarbons and salts build up in coolers. Cleaning falls into planned turnarounds with tight shutdown windows. High pressures for coke, multi-lance operation and ATEX versions are required.
- In the chemical industry, polymer and salt deposits build up in coolers, evaporators and condensers. Because deposits change from unit to unit, a wide pump control range counts.
- In the energy sector, condensers and feedwater heaters with thousands of identical tubes scale up. This is the typical application for multi-lance machines with high flow.
- In the food industry, plate heat exchangers heat and cool product. Cleaning without chemical residue is required, usually at moderate pressure.
- In the steel industry and the paper industry, scale and fibers build up in cooling circuits
KAMAT Technology
| Parameter | Value |
|---|---|
| Typical operating point, heat exchanger cleaning | around 1,000 bar (14,500 psi) |
| Pressure range, heat exchanger cleaning | 300 to 4,000 bar (4,350 to 58,000 psi), depending on deposit |
| Operating pressure, full program | up to 4,000 bar (58,000 psi) |
| Drive power | 15 to 3,000 kW (20 to 4,000 hp) |
| Flow rate | up to 10,000 l/min (2,640 gpm) |
| Design | triplex and quintuplex plunger pumps, modular system |
| Mechanical efficiency | above 90% |
| Control range | 10 to 100% of rated flow, continuously variable via VFD on electric drives |
| Pump head | one-piece forged stainless steel, uncoated |
| Unit configurations | trailer (approved for 100 km/h, 62 mph), baseframe, sound-attenuated, containerized |
| Drive | diesel or electric, ATEX optional |
| Manufacturing | Witten, Germany, since 1974 |
High-Pressure Plunger Pumps
KAMAT builds plunger pumps in triplex and quintuplex design based on a modular system, from 15 to 3,000 kW (20 to 4,000 hp) and up to 4,000 bar (58,000 psi). These properties count most in heat exchanger cleaning:
- Seals are replaced without removing the pump head and without special tools, directly in the field.
- The pump head is forged from one piece of stainless steel and is uncoated. There is no coating that can spall off.
- Mechanical efficiency is above 90%. On diesel units, this goes straight to fuel consumption.
- The pump operates between 10 and 100% of rated flow. On electric drives, a variable frequency drive (VFD) sets the operating point continuously, without throttling and without bypass.
KAMJET Units
For mobile work, KAMAT installs the pump in a KAMJET unit: as a trailer approved for 100 km/h (62 mph), on a baseframe, sound-attenuated or containerized, with diesel or electric drive. The automatic control regulates pressure and flow according to load and cuts diesel consumption by up to 30 percent according to manufacturer data. ATEX versions are available for hazardous areas in refineries and chemical plants.
Why KAMAT
- One unit for several types of work: with a conversion kit, the same KAMJET unit handles heat exchangers, pipe cleaning, decoating and hydrodemolition. For cleaning contractors, the investment is spread across jobs all year round.
- Service during the turnaround: seal changes without removing the pump head, without a crane and without special tools. In a fixed shutdown window, that keeps the schedule.
- Pump, unit, valves and tools from one source, matched to each other down to the nozzle.
- Pressure range up to 4,000 bar (58,000 psi): even for hard coke and silicate deposits there are series whose operating point sits below the pressure limit with margin.
- Short delivery for urgent jobs through pumps and units available now.
- Commissioning, service and maintenance and operator training, worldwide through the global sales network.
- Family-owned company, developing and manufacturing in Witten, Germany, since 1974.
What KAMAT Needs to Size Your System
With these six inputs, KAMAT sizes pump, unit and valve technology for your cleaning task:
- Heat exchanger type: shell-and-tube with straight tubes or U-tubes, plate or spiral heat exchanger, air cooler.
- Tube data: inside diameter, length, number of tubes and material.
- Deposit: type and hardness, with a photo or sample if possible.
- Tooling: hand-held lance, mechanical lance feeder or multi-lance machine, number of lances running at the same time.
- Location: stationary in a wash bay or mobile at the plant, hazardous area classification, noise limits.
- Supply: available electrical service or diesel operation, water connection or closed-loop operation.
Send us the heat exchanger type, tube data and deposit. KAMAT sizes pump, unit and valve technology for your cleaning task.
Downloads
| KAMJET 180 T | Technical Data |  |
562.6 | KB |
| Performance List Plunger Pumps | KAMAT Performance List | |
479.8 | KB |
Frequently Asked Questions About Heat Exchanger Cleaning
Heat exchanger cleaning is the removal of deposits such as scale, sludge, coke and product residue from the heat transfer surfaces of a heat exchanger, so that heat transfer returns to design values. With high-pressure water, also called hydroblasting, the deposit is removed mechanically and without chemicals, typically at around 1,000 bar (14,500 psi).
Deposits of scale, sludge and product residue, known as fouling, act as an insulating layer. Heat transfer drops, pressure drop across the unit rises, and the plant needs more energy for the same duty. In operation this shows up as higher energy consumption per ton of product and unstable process temperatures.
Around 1,000 bar (14,500 psi) is the typical operating point. Depending on the type and hardness of the deposit, the range runs from 300 bar (4,350 psi) for sludge and loose residue to 2,500 bar (36,250 psi) and above for hard scale and coke. KAMAT high-pressure pumps reach 4,000 bar (58,000 psi) and are adjusted continuously to the fouling, via the variable frequency drive on electric units.
On shell-and-tube heat exchangers, a rigid lance or a flex lance travels through each individual tube and removes the deposit with the water jet. The shell side of a pulled bundle and plate packs are cleaned with nozzles and surface tools. Nozzle geometry, pressure and flow rate are matched to tube inside diameter, material and deposit.
Shell-and-tube heat exchangers with straight tubes and U-tubes, plate and spiral heat exchangers, and air coolers can be cleaned with high-pressure water. Because pressure is continuously adjustable, the process also suits thin-walled tubes and copper alloys. Cleaning takes place above the adhesion limit of the deposit and below the damage threshold of the base material.
The UK Water Jetting Association's Code of Practice caps reaction force on hand-held equipment at 250 N (56 lbf), and German DGUV Rule 100-500, Chapter 2.36 sets the same limit with additional measures required above 150 N (34 lbf). There is no OSHA standard for high-pressure water jetting in the United States; the WJTA-IMCA Recommended Practices are the voluntary reference. At 250 N this corresponds to approximately 34 l/min (9.0 gpm) at 1,000 bar (14,500 psi), 24 l/min (6.3 gpm) at 2,000 bar (29,000 psi) and 19 l/min (5.0 gpm) at 3,000 bar (43,500 psi).
No pickling agent remains in the process equipment, and there is no chemically contaminated wastewater that has to be neutralized and disposed of. Seals and base material are not attacked chemically. With filtration, the jetting water can run in a closed loop, which reduces fresh water demand and disposal volume per cleaning cycle.
In continuous operation, intervals of 6 to 12 months are common. Condition-based cleaning is more precise: when pressure drop across the unit rises or the temperature difference between inlet and outlet falls measurably, cleaning is due. Cleaning on measured values avoids unnecessary shutdowns and the gradual increase in energy consumption.
Yes. Mechanical lance feeders and multi-lance machines clean several tubes at once and cut cleaning time per bundle. The operator controls the process from outside the jetting zone, and feed rate and dwell time stay repeatable. KAMAT pump units are designed for continuous duty with semi-automatic and fully automatic tools.
That depends on pressure and on the number of lances running at the same time. For one hand-held lance at around 1,000 bar, a K5500-3 delivering 25 l/min (6.6 gpm) at 1,140 bar (16,550 psi) is sufficient; reaction force is then about 200 N (45 lbf). A K25000-3G delivers 130 l/min (34.3 gpm) at 1,010 bar (14,650 psi): enough for three hand-held lances at the 250 N limit, which together need about 100 l/min (26.4 gpm), or at full flow for a multi-lance machine. The KAMAT Pump Finder makes the preselection, and final sizing is done with KAMAT engineers.
KAMAT keeps a selection of high-pressure pumps and units available for immediate delivery; the current list is on kamat.de under "Units and HP-Pumps available now". For configurations built to customer specification, delivery time depends on frame size and equipment.
KAMAT uses high-pressure plunger pumps in triplex and quintuplex design from a modular system, up to 4,000 bar (58,000 psi), up to 3,000 kW (4,000 hp) and up to 10,000 l/min (2,640 gpm). Mechanical efficiency is above 90%, and the control range is 10 to 100% of rated flow. Seals are replaced without removing the pump head and without special tools. Development and manufacturing have taken place in Witten, Germany, since 1974.
