Detergents; Liquid Penetrant Testing - Riello SP20-DN32 Manuel D'utilisation Et D'entretien

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 destroy 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% concen-
tration by weight, max. temperature 65°C (1.5% by weight
corresponds to 1.75 l of 62% HNO3 for 100 litres 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 corre-
sponds to 3.75 l of 30% NaOH for 100 litres of water).
• Do not use hydrochloric acid or water with a chloride con-
tent of over 300 ppm to clean stainless steel plates.
• Do not use phosphoric acid to clean titanium plates.
Deposits:
Calcium
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 (as these
fluids may damage NBR and EPDM gaskets, limit the con-
tact time to no more than 30 minutes)
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. RIELLO's technical
support team can advise you on the appropriate products.
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