I'm trying to understand the thresholds in both water chemistry and tensile stress which are required to initiate SCC in "yellow" brass fluid fittings exposed to water. i.e. why does the same fitting fail in one installation and not in another, when the water chemistry is almost identical?
Stress corrosion cracking is highly sensitive to certain types of ions in very low concentrations. You should explain what you mean by "almost identical" water chemistry.
regards,
Bojan.
You bring up a good point. My description was pretty subjective. To elaborate (without going into too much detail)... water chemistry reports from multiple facilities show similar levels of constituents which are attributed with SCC in yellow brass, within 5-10% variation from facility to facility. For instance: Chlorides, ~5 ppm; Sulfate, ~1 ppm; Ammonium, < 1 ppm. From what we understand, those levels are considered "low" (from a SCC in brass standpoint). Curiously, yellow brass water fittings are failing at a high rate due to SCC at one facility, but zero failures at other facilities with similar water.
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