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Continued from The MP Blog, p. 13. The following items relate to chemical treatment. Please be advised that the items are not peer-reviewed, and opinions and suggestions are entirely those of the inquirers and respondents. NACE International does not guarantee the accuracy of the technical solutions discussed. MP welcomes additional responses to these items. They may be edited for clarity. Microbial corrosion in water pipeline carbon steel (CS). There have been few leaks reported with insuffcient details. Chlorine is added before the water enters the pipeline network. The client obtained One of our clients has a water analysis from an outside agency internal corrosion in to measure microbial counts and found its utility water pipe- none. Based on the above information, lines. The corrosion is mani- our analysis is as follows, for which we request comments. fested in mounds located mostly at the The saturation indices are in the range bottom of the pipeline. The pipeline is of scale dissolution. The mounds on the pipeline clearly indicate microbiologically infuenced corrosion (MIC). The reason that water sample analysis showed negative microbial count could be the type of microbes, which are mainly sessile and not of a foating type. Hence, they cannot be easily captured in a fowing water sample. We have suggested analyzing corrosion products for carbon and organic carbon to further confrm that the corrosion product has dead microbes. Is there any other definite way to confrm the presence of microbes in the water by taking samples? The client took samples on site using the dipstick method. Q A A negative result for bacteria using dipsticks is not necessarily proof that bacteria are absent. Many bacteria require specialized growth media to detect them, particularly if their environment has a chemistry that is not normally encountered. Species such as pseudomonas can adapt to such environments; however, they then may need a similar environment in the growth media before they will be detectable. You may need the services of a microbiologist. Not all laboratories providing microbiological testing services actually employ microbiologists. The golden rule in MIC is to frst try to prove that the situation has not been caused by MIC at all! Only when you fail to prove this, you can try to fnd a story for the corrosion case in terms of the involvement of "bugs." Here are some ideas: • How are you persuaded that the mounds were caused by MIC mechanisms? One way to fnd out A 62 MATERIALS PERFORMANCE May 2013 NACE International, Vol. 52, No. 5