Accelerated Weld Corrosion in C65500 SB96 CuSi Esterification Vessel

[t4runner1987]

I have exhausted my personal resources. Looking for some guidance. We have a two SB-96 C65500 vessels that typically operate at 118 to 133°C. The previous vessels lasted +30 years and I'm not positive on their operating temperatures then. Current vessels have lasted 10 years and are on the scheduled to be replaced. Some impressive weld corrosion at accelerated rates. I am looking for any publication references for the operating threshold for SB-96 C65000. I have looked at ASME Sec. II Part B where it lists Max temp 204°C. Here's the kicker, whats actually inside the vessel. MMA 4.5%, MAA 1.9%, MEOH 5%, H20 16.5%, H2SO4 23%, MAAm 15%, NH4HSO4 29.5%, HIBAm/HIBA 1%, MHiB 1.8% and Misc 1.8%. These vessels use steam and bayonet heaters for a distillation process and the vapors are collected. I'm currently considering our operating temperatures are to high due to the specific acids and ammonia. Any guidance would be greatly appreciated.

 

[t4runner1987]

 

[EdStainless]

Any help here?

https://alloys.copper.org/alloy/C65500

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P.E. Metallurgy, Plymouth Tube

 

[t4runner1987]

Little bit. I see where it indicates increased corrosion rates at elevated temperatures. Temperatures aren't specific. Acids, water, and salts make for accelerated corrosion as well. Contaminants such as water, sulfides, acids and various organic compounds can increase corrosion significantly, got it. So it seams from some of this data, temperatures above 200°F will pose a problem.

 

[metengr]

Looks like dealloying of silicon from silicon bronze in high-temperature steam, containing acid species.... right out of "The Corrosion of Copper and Its Alloys: A Practical Guide for Engineers, Roger Francis, page 184

 

[t4runner1987]

Looking for these as well.
ASTM G161 Standard Guide for Corrosion Related Failure Analysis
ASM Metals Handbook, “Corrosion,” Volume 13, ASM International, Materials Park, OH.
A. Cohen, “Copper and Copper-Base Alloys,” Process Industries Corrosion – The Theory and Practice, NACE International, Houston,TX, 1986.
ASM Metals Handbook, “Failure Analysis and Prevention,” Volume 11, ASM International, Materials Park, OH.
Corrosion Basics – An Introduction,” NACE International, Houston, TX, 1984, pp. 117.

 

[t4runner1987]

Metengr, thats exactly what i was just looking at, Right out of API 571. Thank you so much for that reference!