ATEX Retractor System TANKO-RT/-RTS
Annexes
Translation - Operating/installation instructions 2020/01
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Appendix 2: Corrosion Resistance of Steels (Excerpts from Data Sheets)
Material number 1.4301 (AISI 304) as a component that does not come into contact with the medium
(e.g. clamp on the clamp connection).
Stainless austenitic chrome-nickel steel
1.4301 is the standard for austenitic chrome-nickel steels. It is used in numerous areas, because of its
high corrosion resistance and ease of processing, as well as its attractive appearance in a high-gloss
polished, ground or brushed condition. Because 1.4301 is not resistant to intergranular corrosion when
welded, if large parts have to be welded and subsequent solution annealing is not possible, 1.4307
should be used.
The moderate carbon content of 1.4301 means that this grade tends to be sensitive. The formation of
chromium carbides and the associated areas of depleted chrome around these depositions make this
steel susceptible to intergranular corrosion. Although there is no risk of intergranular corrosion in the
condition supplied (solution-annealed), it can set in after welding or when used at high temperatures.
It exhibits good corrosion resistance in natural environmental media (water, rural and urban
atmospheres) in the absence of significant chlorine and salt concentrations. 1.4301 is not suitable for
applications involving contact with seawater, nor is it suitable for use in swimming pools.
Material no. 1.4401 (AISI 316)
The corrosion resistance of 1.4401 is significantly better than that of stainless steel grades 1.4301 and
1.4307, particularly when chlorides are also present, thanks to the addition of 2 - 3% molybdenum.
1.4401 has excellent corrosion resistance in natural environmental media (water, rural and urban
atmospheres), as well as in industrial sectors with moderate chlorine and salt concentrations, in the
food industry and the agricultural food sector.
Due to its relatively high carbon content it must be taken into account that 1.4401 is not resistant to
intergranular corrosion.
Furthermore, it should also be pointed out that 1.4401 is not resistant to sea water.
Material no. 1.4404 / 1.4408 (AISI 316L)
The corrosion resistance of 1.4404 is significantly better than that of stainless steel grades 1.4301 and
1.4307, particularly when chlorides are present, thanks to the addition of 2–3% molybdenum.
1.4404 exhibits excellent corrosion resistance in natural environmental media (water, rural and urban
environments), as well as in industrial sectors with moderate chlorine and salt concentrations, in the
food and pharmaceutical industries and in the agricultural food sector. Due to its low carbon content
1.4404 is even resistant to intergranular corrosion after welding.
1.4404 is not resistant to sea water!
Material no. 1.4430
Austenitic TIG welding rod for similar types of stabilized and non-stabilized CrNi and CrNiMo steels,
particularly in chemical plant construction. Resistant to heat and scaling up to 800 °C, and can be used
with wet corrosion up to 400 °C. Not sufficiently resistant to nitric acid attack.
Used for base materials including: 1.4404; 1,4435 and 1.4571.