It is known that Austenitic stainless steels (SS304,SS316,…) are prone to SCC in chloride bearing environments. The chloride is normally controlled within a certain limit to prevent stress corrosion cracking. In some cases, such as hydrotest, standards normally suggest 50 ppm chloride limitation.
In case the chloride content cannot be controlled, a higher alloyed stainless steel or another suitable material is selected to prevent SCC. ASME Section I (PG-5.5) forbids using the austenitic stainless steels in the boiler pressure parts that are in contact with water.
On the other hand Stainless steels are also prone to crevice and pitting corrosion and their application is normally limited to prevent this type of corrosion (1000 ppm is a common restriction for SS316 at ambient temp.)
My question : Why in table A.2 of ISO 15156-3, the level of chloride content is limited to such a broad range ? (for instance to 50000 ppm in presence of max. 1000 ppm H2S and pH>=4.5). Does this imply chloride content becomes less significant for SCC risk in sour service environments?
In case the chloride content cannot be controlled, a higher alloyed stainless steel or another suitable material is selected to prevent SCC. ASME Section I (PG-5.5) forbids using the austenitic stainless steels in the boiler pressure parts that are in contact with water.
On the other hand Stainless steels are also prone to crevice and pitting corrosion and their application is normally limited to prevent this type of corrosion (1000 ppm is a common restriction for SS316 at ambient temp.)
My question : Why in table A.2 of ISO 15156-3, the level of chloride content is limited to such a broad range ? (for instance to 50000 ppm in presence of max. 1000 ppm H2S and pH>=4.5). Does this imply chloride content becomes less significant for SCC risk in sour service environments?
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