In-Plant Corrosion Testing in Ozone Bleach NG Environments, 1999 Engineering Conference Proceedings

Pekka Pohjanne

VTT Manufacturing Technology

P.O.Box 1704

FIN-02044 VTT, Finland

Marko Siltala

UPM-Kymmene, Pulp Center

P.O.Box 42

FIN-68601 Pietarsaari, Finland

The corrosion behavior of different stainless steel grades was investigated with mill tests both in ozone bleaching and in ozone production environments. The corrosion resistance was evaluated both by immersion and electrochemical

tests.

The mill tests showed that the AISI 316L and the other more alloyed stainless steels do have good corrosion

resistance both in the reaction tube and in the ozone reactor (T = 60…70 o C, pH = 2.5…3.0, Cl - = 0.1…0.15 g/l, O3-dosage ca. 3.3 kg/t). The AISI 304L type stainless steel is not suitable for use in ozone bleaching due to poor

localized corrosion resistance. The low corrosion rates of the highly alloyed UNS S31254 and UNS S32654 stainless

steels were surprising.

The ozone gas feed line environment (T = 20…30 o C, pressure 1000 kPa, O3-content = 9.5%) was very corrosive to

all stainless steels examined.