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Food and dairy heat exchanger cleaning

In a pasteuriser the plate pack is a food safety barrier before it is a heat exchanger, and cleaning is when that barrier gets proven. Send the unit details and what is building up, and a specialist who cleans hygienic plate packs will come back to you.

  • UnitsPasteurisers, UHT, tubulars, evaporators
  • DepositsMilkstone, denatured protein, calcium phosphate
  • ReturnsIntegrity tested and swabbed

Submit a cleaning request

Four steps: unit, deposit, postcode, contact details.

  1. 01Unit
  2. 02Situation
  3. 03Site
  4. 04Contact
What needs cleaning?

01What gets cleaned

Pasteuriser packs foul in two distinct layers at two distinct temperatures

Food and dairy heat exchanger cleaning carries a requirement no other sector does. The unit has to come back demonstrably fit for food contact. The plate pack has to be shown to be intact. A pasteuriser regeneration section holds raw product on one side of the plate and pasteurised product on the other, at a deliberate pressure differential. A pinhole there does not reduce efficiency, it fails the process, so cleaning and integrity testing are the same visit.

01

Protein fouling forms below about 110 degrees and mineral fouling forms above it

The two deposits found on dairy heat transfer surfaces behave differently enough that they are treated as separate problems. The lower-temperature layer is protein-rich, soft, voluminous and dominated by denatured whey protein. It forms through the heating section and it responds to caustic. The higher-temperature layer is hard, granular and mostly calcium phosphate, it forms in the hottest sections and holding tubes, and caustic does very little to it. Most packs carry both, in different places, so a single-chemistry cycle always leaves something behind.

Fouls with
Denatured whey protein, casein, calcium phosphate, fat
First symptom
Pressure drop rising, run length between CIPs shortening
Watch for
Which section fouls: it tells you which of the two layers you have
02

The regeneration section is the one where a crack matters most

Regeneration recovers heat by putting incoming raw product against outgoing pasteurised product across a single plate. That plate is the only thing between the two, and the process relies on holding pasteurised side pressure above raw side pressure so that any leak goes the safe way. A hairline crack, a pinhole from chloride pitting or a distorted plate compromises the barrier, and no amount of circulation cleaning will tell you it has happened.

Fouls with
Protein on both sides, plus scale from the water circuit
First symptom
Often none. Detected on test or by product results, not by duty
Watch for
Chloride pitting, stress cracking at ports, plate distortion from over-tightening
03

UHT, evaporators and tubular units foul faster and are cleaned harder

Indirect UHT plant runs hotter than pasteurisation and fouls correspondingly, with run length between cleans measured in hours on some products and not days. Evaporators concentrate exactly the minerals that deposit. Tubular and scraped-surface units on viscous or particulate products carry burn-on that plate chemistry is not designed for. These are the units where the cleaning regime is engineered alongside the process instead of added afterwards.

Fouls with
Burn-on, caramelised sugars, concentrated mineral, fat
First symptom
Run length falling, back pressure rising, product colour drifting
Watch for
Thermal stress cracking, erosion at tube inlets, seal degradation

02What has built up

Milkstone is a mineral deposit and denatured protein is not, and each needs the other stage

Hygienic plant is cleaned every day, so a specialist is called when the daily cycle stops keeping up. That is nearly always a sequence problem, never a strength problem.

DepositWhere it comes fromHow it is removed
Denatured proteinWhey protein and casein coming out of solution onto heat transfer surfaces through the heating section.Hot caustic, with enough contact time. Enzymatic where repeated cycles have baked it hard.
CIP / enzymatic
Milkstone and calcium phosphateMineral crystallising in the hottest sections and holding tubes, and building in whatever protein is already there.Acid after caustic, in sequence. Caustic alone leaves it and hardens what is around it.
Two-stage CIP
Fat and oilCream and high-fat product films, worse on cooling sections where the fat sets rather than flows.Hot alkaline with a surfactant. Temperature above the fat melting point matters more than concentration.
CIP
Caramelised sugar and burn-onSugar-bearing products on UHT, evaporator and scraped-surface duties where local wall temperature is high.Extended alkaline soak, or strip and immersion where it has carbonised onto the surface.
CIP / immersion
BiofilmCooling sections, balance tanks and any dead leg the daily cycle does not reach at velocity.Remove the soil, then sanitise. Sanitiser applied over a biofilm barely penetrates it.
CIP + sanitise
Water-side scaleThe service side: hot water sets, chilled water and glycol circuits, cleaned separately from product.Inhibited acid circulation on the service circuit only, never through the product side.
CIP

03In place or off site

Cleaning a hygienic pack is also the occasion to prove the plates are sound

Restoring duty is the smaller half of the job. The half that matters to a technical manager is what can be demonstrated about the pack afterwards.

  1. 01

    A corrected two-stage CIP recovers most packs without opening them

    Hot caustic for the protein, rinse, acid for the mineral, rinse, at proper temperature and contact time with flow reversal. Where run length between cleans is falling, the cycle is usually the cause and correcting it is the first thing to try because it costs no production time.

  2. 02

    Stripping the pack is what reaches the gasket groove and the port shadow

    Circulation never touches behind a gasket or in a port shadow, and those are where protein and biofilm persist through daily cleaning. Opening the pack means every plate is cleaned and inspected individually, and it is the only route to a pack that is clean, not clean where the flow went.

  3. 03

    Integrity testing is what turns a clean into evidence

    With the pack open, plates are dye penetrant tested or the assembled pack is pressure tested to find pinholes and hairline cracks. On a pasteuriser this is the check that the regeneration barrier is intact, and it is the reason many sites strip on a fixed cycle regardless of how the duty is performing.

  4. 04

    Verification closes the job, and it is documented instead of assumed

    Final rinse, sanitisation, and then confirmation that the surface is clean: swabbing, ATP or protein residue testing to the site's own standard. Food-grade gaskets, the test pressure and the verification results all go on the record that comes back with the unit.

04What happens next

Four steps take a fouled unit from enquiry to a tested return

The enquiry goes straight to a contractor who cleans that unit type. There is no qualifying call in between.

  1. You send the unit details, the deposit and the postcode.

  2. The enquiry goes to a specialist set up for that unit type and that fouling.

  3. They come back with method, timescale and price.

  4. The clean is carried out in place or off site, and the unit is tested before it goes back.

05Questions

Plate integrity, verification and production windows decide how hygienic cleaning is planned

Why is the pasteuriser fouling faster than it used to?

Shortening run length between CIPs almost always means the cycle is leaving something behind, and each run starts on top of the last residue. The usual cause is a sequence problem: caustic without a proper acid stage leaves mineral, and the mineral then gives protein something to key onto.

It can also be upstream. A change in product, in preheat, in raw milk quality or in the water hardness on the service side will all move the fouling rate without anything changing in the pasteuriser itself.

How do we know the plates are not cracked?

You cannot know it from a circulation clean. That is why integrity testing exists as a separate activity. Duty and pressure drop tell you about flow and not about a pinhole.

It is established by opening the pack and testing: dye penetrant on individual plates, or a pressure test on the assembled pack, depending on the unit and the standard the site works to. On a pasteuriser regeneration section that test is a food safety control, and treating it as one, not as maintenance.

What happens if the regeneration section leaks?

Raw product can reach pasteurised product. The process is designed against this by holding the pasteurised side at higher pressure so any leak flows the safe way, and that differential is monitored, but it is a mitigation rather than a guarantee.

That is why the plate is treated as a barrier, not a heat transfer surface. A pinhole in regeneration is a different category of problem from the same pinhole in a cooling section, and it is the one that justifies stripping on a schedule.

How long is the unit out of production?

A corrected CIP cycle fits the normal cleaning window, so effectively no production is lost beyond the cycle itself.

A strip is days instead of hours: break the pack, clean and inspect every plate, integrity test, re-gasket where needed, rebuild, cure, pressure test, then a full CIP and sanitisation before it sees product. On single-line sites that has to be planned into a shutdown; where a spare pack exists it can be swapped and the fouled one cleaned off site.

Are the gaskets food grade?

They have to be, and the paperwork matters as much as the part. Replacement gaskets on product-contact plant should be supplied with declarations of compliance for food contact, and those declarations belong in the job record.

Whether they need replacing is judged plate by plate. Sound, in-date gaskets that are not bonded to the plate are re-used; the point at which a set is renewed is best decided while the pack is already open.

Is the unit swabbed before it goes back into service?

It should be, to whatever standard the site already applies to its own cleaning: swabbing, ATP, or protein residue testing. Cleaning that is not verified is an assertion and not a result.

Say in the enquiry what the site's verification standard is. It changes what has to be done at the end of the job and what documentation comes back with the unit, and it is much easier to plan in than to add afterwards.

What does dairy heat exchanger cleaning cost?

Plate count first, then whether the pack is being opened, then whether gaskets and integrity testing are included. A corrected CIP is at one end and a full strip, test, re-gasket and verification on a large pasteuriser pack is at the other.

Integrity testing and the documentation around it are a substantial part of the scope in this sector. Ask for them explicitly: a quote that leaves them out is not comparable to one that includes them.

How often should a pasteuriser pack be stripped?

Two things drive it and they are different in kind. Performance says strip when run length between CIPs has fallen far enough that circulation is no longer keeping up. Food safety says strip and integrity test on a fixed interval whether or not performance has drifted, because a crack gives no warning through the duty.

The second usually sets the schedule. Many sites work to an annual or shutdown-cycle strip on regeneration sections regardless of how well the unit is running, and treat performance-driven strips as additional to that rather than instead of it.

06Other industries

Fouling follows the process, so every sector fouls its exchangers differently

PharmaceuticalProduct residue and biofilm on jacketed vessels and purified water circuits, with documentation to match.pharmaceutical heat exchanger cleaning →Chemical processingPolymer, salt and process solids on reactor coolers, condensers and interchangers.chemical plant heat exchanger cleaning →Power generationSilt, shell and biofilm through condenser tubes, and scale on auxiliary and lube oil coolers.power station heat exchanger cleaning →HVAC and district heatingLimescale in plate heat interface units and calorifiers, biofilm and sludge in cooling circuits.HVAC heat exchanger cleaning →

A specialist who cleans that unit type answers the request

Unit, deposit and postcode are enough to start. Your details go to a specialist who cleans that unit type. No obligation.

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