Corrosion monitoring of internally fusion bonded epoxy lined pipes

[chrysa1975]

I need corrosion monitoring transmitters to be used in internally fusion bonded epoxy carbon steel piping systems so as any holiday of the FBE to be noticed and underneath CS corrosion to be caught up and avoided. I understand that the element material is usually the same material with the pipe and that the probe body is a superior material from the element and corrosion resistant to the fluid. Could you please advice for the element material considering also that the equivalent material instead of FBE lined items, e.g. for pipes NPS<2 is UNS S31254. Since probe body has to be a superior material from the element and corrosion resistant to the fluid, UNS S31254 or INCONEL 625 may be selected. What about the material of the element? How can I achieve corrosion monitoring of Internally coated pipes?

 

[SJones]

I'm not quite sure about the aims of the monitoring programme and the function of the 'transmitters'. The only way that you will determine whether there are holidays in the coating is by an iron count of the fluid. As you know, there will always be holidays anyway; so, perhaps you will be trying to assess fluid corrosivity as a means of quantifying the degradation rate at holidays but that should go against the technical reasoning for selecting internal FBE as a corrosion control measure in the first place, i.e. you should have already had a handle on the degradation rate(s). The 'transmitters' could then be electrical resistance (ER) probes in order to give a reasonably rapid response time in detecting change of corrosivity (assuming that the internal fluid environment is conducive to using ER probes - is it seawater by any chance because then galvanic or LPR probes might also come into play?).

Try to get hold of NACE International Publication 3T199 Techniques For Monitoring Corrosion & Related Parameters In Field Applications and determine exactly why you are measuring, what you want to measure, and what you are going to do with the data.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdoweb/