Vahterus Plate - Fluids

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3.2 Fluids
The structural materials are selected based on the information (media, temperatures,
ows)providedbythecustomer.YoucanalsocontactVahterusformaterialandow
director material options.
Iftheheatexchangerisusedinconditionsthatdierfromthoseforwhichitwasde-
signed (listed on the Technical Data sheet), its ability to function must be checked. For
example,iftheviscosityoftheuidvariesaccordingtoconditionsthatdierfromthe
informationontheTechnicalDatasheetandcouldresultinadierenceinpressureof
more than 200 kPa between the exchanger and the incoming and outgoing connectors,
Vahterus should be contacted to re-assess the load situation.
Before approving the heat exchanger materials, please ensure that they will stand up to
the conditions to which they will be subjected during his process. Acid- resistant steel
is prone to forms of corrosion, e.g. intergranular corrosion, pitting corrosion, stress
corrosion and biological corrosion. The chloride content of water can cause corrosion
in AISI 316L/ 1.4404 plate materials in a short space of time. When water is boiling, in
particular, it causes chloride precipitation and this can lead to corrosion at quite small
concentrations.
OtherfactorscausingariskofcorrosionarepH,theliquid’sowrate,dirtontheplate,
impurities,etc.,whoseeectshouldbeassessedforeachindividualprocess.Ifthere
is a risk of corrosion, more durable materials such as AISI 904L, SMO 254, Duplex or
titanium should be considered.
NB
For special instructions regarding the quality of water in steam generators, contact
VahterusSales.Pleaseinformusifunstableuidsareusedintheprocess.
General recommendation for water quality when AISI 316L
plate material is used in +20°C
Variable Unit
Recommended quality limits for
water for AISI 316L
Hydrogen ion
concentration
pH 6-9
Alkalinity (as CaO3) mg/l < 300
Chloride mg/l
< 500 mg/l at 25°C
< 200 mg/l at 50°C
< 60 mg/l at 80°C
0 mg/l, when T > 100°C
* Contact Vahterus when > 100°C
Sulphate mg/l < 100
KMn04 - consumption mg/kg < 20
Aluminium mg/l < 0.3
Iron (Fe) mg/l < 0.3
Manganese mg/l < 0.1
Sodium + Potassium mg/l < 200
Conductivity mS/m < 200
Calcium mg/l < 20