Food & Beverage Plant Equipment Cleaning & CIP System Maintenance

Abstract: Plate heat exchangers, fermenters, mixing tanks and multi-effect evaporators in food and beverage lines run on milk, syrup, wort and seasoning. Denatured protein and fat deposit on heated surfaces, sugar scale, beer stone and carbonate scale form on tank and pipe walls, and wet areas grow biofilm. These deposits cut heat-transfer efficiency, push pasteurisation temperatures off specification and act as a permanent microbiological reservoir that shortens shelf life. This article walks through the fouling signature and diagnosis of each major equipment type, when CIP is enough and when dismantled off-line cleaning is required, the alkali-rinse-acid-rinse-sanitise process route and agent selection rules, and how cleaning residue and cleaning effect are verified, with an anonymised case study.

1. Why Food and Beverage Equipment Fouls Faster Than General Industrial Equipment

The product itself is the fouling source. Dairy carries protein and fat, beverages and syrups carry sugars, beer carries wort residue and hop resins, and condiments carry starch and salt. None of this is a problem at ambient temperature, but once it meets a steam or hot-water surface the protein denatures and adsorbs onto the metal wall as a dense layer that plain water will not shift.

Process heat multiplies the fouling rate. Plate surfaces in pasteurisation and UHT service reach 75-140 °C, exactly the range where protein denaturation is most active, and in multi-effect evaporators the concentration rises stage by stage so that components with falling solubility precipitate straight onto the heat-transfer surface. Water hardness and the minerals carried in from the piping add carbonate scale at the same locations.

The consequences run on two levels. First, process loss: the thermal conductivity of the deposit layer is far below that of stainless steel, so the same steam input delivers less heat, pasteurisation temperature falls short of set point, evaporation capacity drops and energy consumption rises. Second, hygiene risk: protein, fat and sugar residues are an ideal growth medium, so wet tank and pipe walls develop biofilm that routine rinsing cannot remove and that keeps re-contaminating the line.

2. Equipment Types, Fouling Signatures and Diagnosis

Food and beverage plants are built mostly in 304 and 316L stainless steel, with carbon steel and copper in utilities. Fouling composition differs sharply from one equipment type to the next, so the deposit must be sampled and identified before the chemical system is chosen, otherwise the wrong agent can corrode the metal or roughen the surface. Deposit identification follows the simple qualitative methods of GB/T 25146-2010 Table 1.

Copper-bearing equipment and any circuit that may see chloride deserve special attention. Stainless steel is at risk of pitting and stress corrosion cracking in chloride-bearing solutions, and clause 5.2.9 of GB/T 25146-2010 limits chloride in the cleaning solution to no more than 25 mg/L when stainless steel is present. Copper and copper alloys require control of oxidising media and ammonia-bearing compounds together with BTA-type copper inhibitors.

3. Choosing Between CIP and Dismantled Off-Line Cleaning

CIP (clean-in-place) is the default route on food lines: cleaning solution circulates through a circuit made up of tanks, piping and heat exchange equipment, and spray-ball coverage plus flow velocity carry the deposit away without dismantling anything and with minimal downtime. CIP only works when spray balls are clear, return flow is unobstructed and circuit velocity is sufficient.

When CIP fails, it is usually for one of three reasons: plate heat exchanger channels are narrow enough that compacted deposit in the plate pack is out of reach of the circulating solution; spray balls are plugged by product residue or scale so the upper tank shell is never wetted; or the deposit has matured into biofilm or dried-on solids that block chemical action at the surface. The diagnosis is direct: if pasteurisation temperature still falls short, exchanger differential pressure keeps climbing, or a wipe test on the tank wall still shows a film, dismantled cleaning is due.

Off-line cleaning suits plates, filling valves and small-bore exchanger tubes that CIP cannot reach. Plates are dismantled and soaked or sprayed individually, and gaskets are handled separately so that prolonged contact with strong alkali or chlorinated agents does not age them; the pack is re-tightened to the manufacturer's specified dimension. In practice the two routes are combined: CIP for day-to-day control, plus a scheduled dismantled deep clean driven by the calendar or by running indicators.

4. Process Route: Alkali - Rinse - Acid - Rinse - Sanitise

Chemical cleaning of food equipment follows a five-step route in which each step is controlled separately; alkali and acid are never run back to back. Step one is alkaline cleaning with an NaOH-based compound plus Surfactant, which saponifies fat, hydrolyses protein and disperses organic residue. Coupons of the same material as the equipment are hung in the circuit from this step onward (clause 5.2.11), and cleaning temperature and duration are set from deposit thickness and coupon trials.

Step two is the intermediate rinse, using soft or demineralised water to displace spent alkali and loosened deposit. A poor rinse carries organic load into the acid stage, wasting acid and risking fresh precipitation. Step three is acid cleaning: milk stone, carbonate scale and beer stone are removed with HNO3-based or Citric Acid-based compounds together with an inhibitor. Stainless steel equipment should avoid hydrochloric-acid agents, because residual chloride is a direct cause of pitting. Ferric ion is monitored during acid cleaning under clause 5.2.10, with reducing or complexing agents added above 1000 mg/L. Specific dosing ratios are set from deposit type and coupon trials and are not listed here.

Step four is the final rinse, run until discharge pH and conductivity approach the incoming water and iron is within limits so that no flash rust forms (clause 5.2.8 requires no secondary rust, no copper plating and no over-pickling). Step five is sanitising, by hot-water circulation or a Peracetic Acid type sanitiser; chlorinated sanitisers should not be used routinely on stainless steel surfaces. The line is then flushed with sterile or process water and sampled to confirm sanitiser residue meets the customer's internal specification.

5. Verification and Acceptance

Acceptance runs on two tracks: the metal side, judged against GB/T 25146-2010, and the hygiene side, judged against the customer's internal specification and food production hygiene requirements. Both need records, because a visually clean surface is not evidence.

Handover documentation covers the cleaning procedure and process card, agent certificates and food-grade statements, coupon corrosion monitoring records, process records (temperature, time, concentration and iron titration), rinse water reports, cleaning and sanitising verification reports, and waste disposal records.

6. Safety, Waste and Site Organization

Cleaning in food plants usually runs after shift or inside a shutdown window, so safety arrangements are agreed in advance. Acids and alkalis are stored separately and issued to named staff, and dilution always adds alkali to water, never the reverse. Operators wear acid-resistant suits, goggles, face shields and acid-resistant gloves, with a wash-down water point and first-aid supplies kept close by. Tank entry is confined-space work and requires a permit: forced ventilation with oxygen and gas testing, a safety attendant with external rescue equipment, and explosion-proof equipment inside the vessel.

Waste streams are segregated. Spent alkaline and spent acid are collected separately, never mixed with sanitising waste, neutralised to pH 6-9 and handed to a licensed contractor or discharged according to the plant's treatment requirements; fat-bearing degreasing waste is collected on its own to keep emulsified oil out of the biological stage.

7. Case Study: Plate Heat Exchanger and Fermenter Cleaning at a Dairy Plant

In August 2026 Blue Star Cleaning cleaned a batch of equipment at a dairy plant in East China, covering pasteurisation plate heat exchangers, fermenters and mixing tanks plus the associated CIP piping. The symptoms reported before cleaning were a pasteurisation temperature that could not be held after several hours of running, rising plate-pack differential pressure and a visible film on tank-wall wipe tests.

Work was organised by equipment group: plate packs were dismantled and plates soaked individually, gaskets handled separately and the pack re-tightened to the specified dimension; fermenters and mixing tanks had their CIP spray balls cleared first, then ran the alkali - intermediate rinse - acid - final rinse sequence with sanitising and sterile-water flushing at the end. Chloride in the stainless-steel circuits was held at no more than 25 mg/L throughout and same-material coupons determined the corrosion rate. After cleaning, every item passed: scale removal and wipe tests, coupon corrosion rates within limits, rinse water pH and conductivity back to incoming levels, and surface swab and ATP results within the customer's specification. Pasteurisation temperature came back stable, plate-pack differential pressure returned to its normal band, and the plant added dismantled deep cleaning to its annual maintenance plan.

8. Frequently Asked Questions

Can strong alkali and acid cleaning leave residue that affects the product?

No, provided the final rinse and sanitising steps are completed. Blue Star Cleaning runs the five-step alkali - rinse - acid - rinse - sanitise route, judges the final rinse on discharge pH, conductivity and iron, then flushes with sterile water after sanitising and samples to confirm residue meets the customer specification. Food-grade statements and certificates are supplied for every agent used.

How do we know CIP has stopped working, and how often is dismantled cleaning needed?

Watch three running indicators: whether pasteurisation temperature can still be held, whether plate-pack differential pressure keeps rising, and whether a wipe test on the tank wall still shows a film. Any one of them means CIP has reached its limit. There is no fixed interval - it depends on product type, running hours and water quality, and is normally tied to the annual shutdown. Blue Star Cleaning will survey the plant first and then propose a schedule; call 18952832843.

Does dismantling plate heat exchangers damage the gaskets?

Not when the work is done to procedure. Gaskets are removed and handled separately so that prolonged contact with strong alkali or chlorinated agents does not age them, and plates are inspected for pinholing and deformation before the pack is re-tightened to the manufacturer's dimension. Blue Star Cleaning checks gasket condition during dismantling and reports any that need replacing so the customer can decide.

How is a clean verified, and what documentation do food audits expect?

The metal side is judged against GB/T 25146-2010: scale removal against Table 3, corrosion rate against Table 2, and passivation film by the ferroxyl or blue-spot test, supported by coupon records. The hygiene side follows the customer specification with rinse water pH and conductivity plus surface swab and ATP testing. Blue Star Cleaning issues process records and verification reports, bound into a file for audits and customer inspections.

How is food and beverage plant cleaning priced?

Pricing combines equipment type, material and deposit: plate heat exchangers by plate count and cleaning method, tanks and vessels by volume and spray coverage, CIP piping by diameter and length, and utility equipment separately. Blue Star Cleaning surveys the site and analyses a deposit sample free of charge, then issues a scope and quotation; invoicing follows acceptance. Call 18952832843.

All cleaning processes and acceptance criteria in this article follow GB/T 25146-2010 Quality acceptance specifications of chemical cleaning for industrial equipment.

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