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A platform for research: civil engineering, architecture and urbanism
Stainless steels for water systems
The aim of the contract was to assess the susceptibility of standard stainless steel tube grades and fittings to corrosion in 'worst case' potable and related water environments. For this purpose, five stainless steel test circuits were constructed. These included a 'high chloride' (HC) (80 deg C, 60 ppm Cl), biocide (B) (40 deg C, 50 ppm 'free' Cl), microbially induced corrosion (MIC) (35/25 deg C, seeded with sulphate reducing and aerobic bacteria), low chloride (LC) (70 deg C, 50 ppm Cl) and control (CMIC) (25 deg C, 30 ppm Cl (water supply level)) circuit. Each of the circuits incorporated a large number of test loops fabricated from 304 and 316 (thin-walled, BS 4127/2) and 316 (thick-walled, DIN 2463) stainless steel tube. The test loops were assembled using a number of fitting/joining systems, including 304 and 316 stainless steel capillary fittings joined using solder, braze and adhesive fillers, 316 stainless steel and brass compression fittings, and 316 (thick-walled) stainless steel, 'Mannesmann' press fittings. Copper capillary and polybutylene compression fittings were also included in testloops exposed in the B circuit for comparison purposes. The circuits were also used to assess the level of transfer of iron, nickel and chromium to the water. The general performance of 304 and 316 stainless steel tube, exposed in their as-received condition in the five circuits for the whole of the operating periods, was excellent. Most of the corrosion problems identified related to the poor corrosion properties of fitting components and lack of fitting integrity. In the case of the most aggressive HC circuit, a gradual increase in the number of corrosion problems was observed over the 22-month operating period. These were mainly associated with the exposure of cold-worked and prescaled 304 stainless steel tube to excessive chloride levels (600 ppm), impaired corrosion resistance of nitrided 316 stainless steel, compression fitting ferrules and isolated cases of sub-standard joining. The work has demonstrated that the corrosion resistance of 316 (thin- and thick-walled) stainless steel tube is not compromised by the worst case conditions investigated in this study.
Stainless steels for water systems
The aim of the contract was to assess the susceptibility of standard stainless steel tube grades and fittings to corrosion in 'worst case' potable and related water environments. For this purpose, five stainless steel test circuits were constructed. These included a 'high chloride' (HC) (80 deg C, 60 ppm Cl), biocide (B) (40 deg C, 50 ppm 'free' Cl), microbially induced corrosion (MIC) (35/25 deg C, seeded with sulphate reducing and aerobic bacteria), low chloride (LC) (70 deg C, 50 ppm Cl) and control (CMIC) (25 deg C, 30 ppm Cl (water supply level)) circuit. Each of the circuits incorporated a large number of test loops fabricated from 304 and 316 (thin-walled, BS 4127/2) and 316 (thick-walled, DIN 2463) stainless steel tube. The test loops were assembled using a number of fitting/joining systems, including 304 and 316 stainless steel capillary fittings joined using solder, braze and adhesive fillers, 316 stainless steel and brass compression fittings, and 316 (thick-walled) stainless steel, 'Mannesmann' press fittings. Copper capillary and polybutylene compression fittings were also included in testloops exposed in the B circuit for comparison purposes. The circuits were also used to assess the level of transfer of iron, nickel and chromium to the water. The general performance of 304 and 316 stainless steel tube, exposed in their as-received condition in the five circuits for the whole of the operating periods, was excellent. Most of the corrosion problems identified related to the poor corrosion properties of fitting components and lack of fitting integrity. In the case of the most aggressive HC circuit, a gradual increase in the number of corrosion problems was observed over the 22-month operating period. These were mainly associated with the exposure of cold-worked and prescaled 304 stainless steel tube to excessive chloride levels (600 ppm), impaired corrosion resistance of nitrided 316 stainless steel, compression fitting ferrules and isolated cases of sub-standard joining. The work has demonstrated that the corrosion resistance of 316 (thin- and thick-walled) stainless steel tube is not compromised by the worst case conditions investigated in this study.
Stainless steels for water systems
Nichtrostender Stahl für Wasserleitungen
Lewus, M. (author) / Tupholme, K. (author) / Hobson, S. (author) / Lee, B. (author) / Dulieu, D. (author)
1997
184 Seiten, 73 Bilder, 48 Tabellen, 56 Quellen
Report
English
Corrosion of stainless steels in potable water systems
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