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Plate heat exchanger cleaning

A plate pack loses duty in the trough contact points and the ports, and whether it can be opened decides everything that follows. Send the make, the plate count and the deposit, and a specialist who cleans that construction will come back to you.

  • ConstructionsGasketed, brazed, welded, semi-welded
  • Cleaned byCIP circulation or strip and immersion
  • ReturnsPlates gauged, pack pressure tested

Submit a cleaning request

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

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

01The unit

Construction decides whether the pack can be opened, and opening it decides what can be proven

Plate heat exchanger cleaning divides on one question before any other: can the pack be opened. A gasketed unit comes apart and every plate can be seen; a brazed unit never comes apart at all; welded and semi-welded packs sit between the two. That single fact decides the method, the price, the downtime and, most importantly, whether the clean produces any evidence about the condition of the plates.

01

Gasketed packs come apart, so they can be inspected as well as cleaned

A gasketed plate heat exchanger is held in a frame under compression, with each plate sealed to the next by an elastomer gasket. Undoing the tie bars and separating the plates gives access to every square millimetre of heat transfer surface, and that is the only condition under which plate thickness, pitting and cracking can be established. Dye penetrant testing on separated plates finds the hairline cracks that cause cross-contamination between circuits. The failure a circulation clean cannot detect and cannot fix.

Cleaned by
CIP where the deposit is soluble; strip and immersion where it is not
Gasket life
Assessed plate by plate. Repeated hot chemical cycling shortens it
Comes back
Plates gauged, gaskets assessed, pack rebuilt and pressure tested
02

Brazed packs cannot be opened, so they are judged on flow rather than on sight

A brazed plate heat exchanger is a sealed assembly with no gaskets and no tie bars. There is no route in, so cleaning is circulation only: chemistry pumped through the existing connections, usually hot, usually reversed part way through so the deposit is attacked from both directions, then flushed. Success is measured on recovered pressure drop and recovered duty, because nothing can be seen. Where circulation fails on a brazed unit, the answer is usually replacement, not a more aggressive attempt.

Cleaned by
Circulation only. Back-flushing where solids are the problem
Judged on
Pressure drop and duty recovered, since the surface cannot be inspected
Limit
Once circulation stops working there is no next step but replacement
03

Welded and semi-welded packs allow more chemistry and less inspection

A semi-welded pack pairs plates in welded cassettes, with gaskets between the pairs. One circuit is sealed against the gasket chemistry and the other is not. That is why it is specified for refrigerants and aggressive media. Fully welded packs have no gasket line at all. Both can take chemistry that would destroy a gasketed unit's elastomer, and both restrict how much of the surface can be reached or seen. Access ports on some welded designs allow lancing and soaking that a brazed unit will not accept.

Cleaned by
Circulation, with lancing and soaking where access ports allow
Advantage
Tolerates chemistry that would attack a gasket set
Limit
Partial or no visual access, so condition is inferred instead of seen

02What has built up

Plate packs foul where the flow is slowest and not where the heat transfer is highest

The herringbone pattern that makes a plate pack efficient also creates contact points and low-velocity lanes, and that is where deposits start.

DepositWhere it comes fromHow it is removed
ScaleHardness precipitating on the hot side and at the outlet, worst where velocity drops between troughs.Inhibited acid circulation, matched to the plate material and the gasket set.
CIP
Protein and productFood, dairy and brewing duties where product denatures onto the plate surface.Hot caustic first, then acid. One stage alone leaves the other deposit behind.
Two-stage CIP
BiofilmCooling water and seawater duties, establishing in the ports and behind the gaskets.Alkaline or oxidising circulation, then a dosing regime, or it returns.
CIP
Oil and greaseLube and quench oil coolers, and any duty where oil crosses to the water side.Hot alkaline or solvent circulation; degreasing off site where it has carbonised.
CIP / immersion
Fibre and solidsProcess streams carrying fibre, catalyst fines or silt, which block ports instead of coating plates.Back-flushing, or opening the pack. Chemistry does nothing to something never dissolved.
Back-flush / strip

03What 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.

04Questions

Construction, gasket condition and plate material decide how a pack is cleaned

Can a plate heat exchanger be cleaned without opening it?

Usually yes, and on a gasketed unit it is normally the first attempt. Circulation through the existing connections restores duty quickly where the deposit is soluble, and it costs a fraction of a strip.

It has two limits. It will not shift baked, fibrous or particulate fouling, and it tells you nothing about the plates themselves. A unit suspected of cross-leaking gets opened, because that is a question circulation cannot answer.

How do I know whether my unit is gasketed or brazed?

Look for the frame. A gasketed unit has a fixed plate, a pressure plate, tie bars running between them and a visible stack of plates you can count on the edge. A brazed unit is a solid block with connections and no visible plate edges or bolts.

Semi-welded looks like a gasketed unit from outside because it is in the same kind of frame. The welded pairs are internal. The nameplate or the model number will normally settle it, and it belongs in the enquiry because it changes what can be done.

Will cleaning damage the gaskets?

Hot chemical cycling does shorten gasket life, and repeated aggressive CIP is a common reason a pack starts weeping. Nitrile and EPDM both have limits on temperature and on the chemistry they will tolerate, and a cleaning specification written against the deposit alone can destroy a gasket set.

This is one of the arguments for stripping periodically instead of circulating indefinitely. Once the pack is open, the gasket set can be assessed and renewed at the point where the strip labour is already being paid for.

What is a cross-leak and how is it found?

It is a crack or pinhole through a plate, letting one circuit into the other. On a dairy pasteuriser that is a food safety failure; on a refrigeration duty it puts refrigerant into water; on a jacket cooler it puts oil where it should not be.

It is found by opening the pack and dye penetrant testing the plates, or by pressure testing the assembled pack with one side isolated. It cannot be found by circulation cleaning, and it usually cannot be found by looking at performance figures either.

How long does a plate pack clean take?

Circulation on an accessible unit is usually a single shift, and frequently done overnight so no production time is lost at all.

A strip is days. Breaking the pack, cleaning and inspecting each plate, renewing gaskets where needed, allowing adhesive to cure, rebuilding and pressure testing is a sequence that cannot be usefully compressed. Plate count is what moves the number most.

What does plate heat exchanger cleaning cost?

Plate count first, then whether the pack is opened, then whether gaskets are renewed. A forty-plate package unit circulated in place and a nine-hundred-plate dairy pack stripped, cleaned, re-gasketed and tested are not comparable jobs.

Stating the make, model and plate count in the enquiry is what makes a real number possible. Without them any figure is a range.

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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