Materials Performance

MAR 2017

Materials Performance is the world's most widely circulated magazine dedicated to corrosion prevention and control. MP provides information about the latest corrosion control technologies and practical applications for every industry and environment.

Issue link: http://mp.epubxp.com/i/792600

Contents of this Issue

Navigation

Page 15 of 80

13 NACE INTERNATIONAL: VOL. 56, NO. 3 MATERIALS PERFORMANCE MARCH 2017 THE BLOG Continued f rom page 11 ClO 2 is a unique area of technolog y that is quite complex. When you publish such articles, you need to make sure that they are being peer-reviewed by people who are well versed in the technolog y. Otherwise, questions like those above are missed. Thanks, enjoy your journals. Greg D. Simpson, R&D;, Pureline Treatment Systems Author Reply Thank you for your questions. I need to point out that MP has a strict limit on size for contributions and case histories have to be conf ined to the essentials. This was a f iref ighting exercise and when tubes are leaking, causing shutdown, you need to f ind a solution quick ly. Our dis- cussion centered on the perceived causes and our solution. However, below we have tried to answer your questions. 1. e method for generation of ClO 2 is vendor-related information and can't be disclosed. 2. e treatment was continuous with ClO 2 concentration in the range between 0.6 and 0.8 mg/L inlet concentration. Excursions were up to 1.1 mg/L. 3. Although the graph was not for the water we were dealing with, it showed the persistence of ClO 2 compared with chlorine. Most of the information on ClO 2 was taken from our reference 3, which we found very helpful. 4. e cooling water loop is only partly once through. A temperature control recycles up to 60% of the outfall water back to the cooling water system. e ClO 2 levels measured in the outfall indicated low values <0.1 mg/L. However, as mentioned in the article, the detection method only detected ClO 2 . Other breakdown products; for example oxidizers like chlorite, were not measured. Francis showed (MP 21, 8, 1982, p. 44) that continuous chlorine levels of more than a few tenths of a ppm will increase erosion-corrosion of aluminium brass tubes, especially when no ferrous sulfate dosing is carried out. While chlorite is not such a strong oxidizer as chlorine, a concentration of a few ppm would be more than enough to hinder protective film formation and increase the risk of erosion-corro- sion, by raising the redox potential. 5. ClO 2 injection rate was calculated based on flow meter data. Concen- trations in the outfall were moni- tored on a weekly basis based on HACH Method 10126. No monitoring of chlorite levels was done. 6. No bacterial testing was done. e effect of dosing ClO 2 was based on heat exchanger inspections during maintenance work. It was concluded that ClO 2 had a positive effect in reducing biological growth. erefore, the company decided to continue dosing, but replace the material in the heat exchanger. Roger Francis, FNACE, RFMaterials, and Claes Hedvall , Borealis AB

Articles in this issue

Links on this page

Archives of this issue

view archives of Materials Performance - MAR 2017