Vahterus Plate, User Manual

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3.2 Fluids

The structural materials are selected based on the information (media, temperatures, 

flows) provided by the customer. You can also contact Vahterus for material and flow 

director material options. 

If the heat exchanger is used in conditions that differ 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 fluid varies according to conditions that differ from the 

information on the Technical Data sheet and could result in a difference 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 flow rate, dirt on the plate, 

impurities, etc., whose effect 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 fluids 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

Potassium

mg/l

< 200

Conductivity

mS/m

< 200

Calcium

mg/l

< 20