Mel, In the table you mentioned from AWWA research foundation, does it include the ppm of ammonia threshold for SCC in 90-10 Cu-Ni?
In addition, does anyone have data on the cracking initiation time of 90-10 Cu-Ni? There are some data on other copper alloys, but I couldn't find any for Cu-Ni.
Thanks,
Yingying
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Yingying Wei
Air Products and Chemicals, Inc.
Allentown PA
(610) 481-2245
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Original Message:
Sent: 09-28-2022 09:36 AM
From: Mel Esmacher
Subject: Stress corrosion of Cu in NH4- environment
Feng,
There are several good references on copper alloy SCC in ammonia containing environments, I wrote Chapter 14 of the book; Stress Corrosion Cracking – Theory & Practice, 2011, Ed. Raja/Shoji, entitled "SCC in Boiler and Cooling Water Systems, where I list several references related to brass (Cu-Zn) SCC. In this chapter, there is a chart that ranks SCC risk of various classes of copper alloys (from MTI Publication No.15), and I also list a table from AWWA Research Foundation that lists the ppm of ammonia threshold for SCC in Admiralty Brass as less than 0.2 ppm ammonia.
In regards to pure copper (99.9%), I do believe the literature has case histories about SCC failures of high purity copper in ammonia, etc., but typically the ammonia level would be greater to cause SCC in a high purity copper alloy, as compared to Cu-Zn alloys.
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Original Message:
Sent: 9/27/2022 11:49:00 PM
From: Min Feng
Subject: Stress corrosion of Cu in NH4- environment
Hello all
There are some reports about stress corrosion cracking of copper(alloyed with zinc) in the NH4- environment , is there any specific case study material?
Now I have a chiller with pure copper tube (99.9%Cu), does this have risk of stress corrosion cracking in the NH4- or nitrates environment? Any threshold concentration limit for pure copper NH4- stress corrosion cracking?
Thanks
BR
Feng Min
Fixed Equipment Engineer
Site Maintenance Department
Nouryon(诺力昂)