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Procedure:
1) Completely drain all the circuits (if this is not possible, run fresh water through the circuits until the process fluids have been
completely flushed out).
2) Clean with fresh water (with a low chloride content for the stainless steel plates) at a temperature of around 40°C to eliminate
all traces of the process fluids.
Run this water in the opposite direction of normal operation. An even better result can be obtained by running the water
alternately in one direction and then the other (this is recommended for steam applications or to eliminate residues such as fibres
and particles). The use of filters upstream of the heat exchanger will reduce the need for this.
3) Completely drain the water from the circuits and connect the CIP unit. Do not let the solution sit in the exchanger.
4) For even better cleaning, use a centrifugal pump installed between the CIP unit and the heat exchanger. Circulate the
detergent solution in the opposite direction to that of the fluids so as to eliminate all traces of dirt.
5) Circulate a quantity of detergent solution at above the nominal flow rate but without exceeding the maximum allowable flow
rate (determined by the nominal diameter).
6) Thoroughly flush both circuits with fresh water.
5.5 - Detergents
- Never use hydrochloric acid (HCl) or chlorinated compounds with stainless steel.
- Never use phosphoric acid with titanium.
- Suitable detergents may be obtained from specialised firms. Specify the plate and gasket types to obtain a detergent that will
not remove the protective oxide layer on the plates or damage the gaskets.
- Nitric acid (HNO3) and sodium hydroxide (NaOH) may be used to clean stainless steel and titanium plates.
- Polyphosphates may also be used.
Descaling
- Use a nitric acid (HNO3) or citric acid solution: 1.5% concentration by weight, max. temperature 65°C (1.5% by weight
corresponds to 1.75 l of HNO3 at 62% per litre of water) or a polyphosphate solution (NaPO4 or Na3PO4): 1.5% max.
concentration by weight, max. temperature 50°C.
Degreasing
- Degrease stainless steel or titanium plates with a sodium hydroxide (NaOH) solution: 1.5% max. concentration by weight,
max. temperature 65°C (1.5% by weight corresponds to 3.75 l of NaOH at 30% for 100 litres of water).
- Do not use hydrochloric acid or water with a chloride content of over 300 ppm to clean stainless steel plates.
- Do not use phosphoric acid to clean titanium plates.
Deposits:
Calcium scaling
Recommended detergents: 4% nitric acid solution at 60°C max. - 4% citric acid solution at 60°C max.
Oils and greases
Recommended detergents: Paraffin or kerosene (these fluids can damage the NBR and EPDM gaskets - limit contact
to 1/2 hour, maximum)
Sludges, metal oxides
Recommended detergents: 8% nitric acid solution at 60°C max. - 4% citric acid solution at 60°C max.
Organic matter
Recommended detergents: 2% sodium hydroxide solution at 40°C max.
5.6 - Liquid penetrant testing
- Corrosion, galvanic coupling and erosion can create holes in the plates. As such damage is not always visible to the naked
eye, we recommend performing liquid penetrant tests to check for holes or microcracks. CIAT’s technical support team can
advise you on the appropriate products.
Summary of Contents for ITEX NA 10.51 D
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