I would like to know how to prevent internal parts of equipments which are not in service for a long time from corrosion.In our plant some of equipments ( towers and coolers )are in two set and in pararel so at a time only one of them is in service and the other will be out of service for a long time ( more than two years).We have faced with severe internal corrosion which lead us to extra works and cost ( retubing ,...).We think to use nitrogen blanket but for some reasons it was not successfull.Any comments would be appreciated.

NON-USED EQUIPMENT STORAGE FROM INTERNAL CORROSION Nitrogen blanketting, under positive pressure, is the most effective and may be one of the economical means for preventive internal corrosion in non-used pressure vessels, turbine / compressor housing etc - with all bolts, flanges, man-hole and vessel boxed up well. Since already corrosion is seen in some of the exchangers - an assessment is to be done to the extent of damage before blanketting with Nitrogen is done. Tubes which are suspected to be on the verge of failure or with severe internal pitting / corrosion may have to be leak /kill tested before nitrogen blanketting is done. C.V.Srinivasan Nishi Engineers Pvt Ltd Chennai 20 India August 17 E-mail: nishi@vsnl.com >Masoud: > >The simple answer is to keep the equipment dry. If the >equipment is corroding then water ingress is occurring >somewhere. Keep manways, flanges, etc. bolted, etc. >Nitrogen has been used to maintain an inert atmosphere, >however, the vessel has to be tight. otherwise excessive >nitrogen will be used. There are also various inhibitors >that can be used, including those that emit vapors, spray >on, etc. > >At the other extreme, completely filling the vessel with de >oxygenated or inhibited water has been successful in >preventing corrosion. This approach has been used with >success in boiler tubes. > >Hope this helps! > > >David Hendrix >The Hendrix Group Inc.

Masod et al As Additional information on non-sued equipment storage: Nitrogen blanketting is not a new method but has been done quite successfully since 1975-1976 for our spare high speed turbine and high speed compressor rotors (when i was in service). This has been quite successful -if the care specified by M.J.Cronin- is ensured and taken care during preservation. Re-use of spare rotors has not given any problem if preserved under nitrogen blanketting -kept and monitored under positive pressure of 5-10 PSIG with periodic pressure gauge checks and for leaks in the boxes kept for storing the usedrotors. Trust this is of help to you. C.V.Srinivasan India August 19,2004 E-mail:nishi@vsnl.com >masood, et al... > >Nitrogen blanketing is most advantageous when the internal >surfaces are extensive and inaccessable. Boiler internals >are a good example. > >My experience has been: > >- Develop a procedure for drying and blanketing > >- Use quality dry nitrogen, (keep testing records) > >- Use forced hot air to ensure the internals are dry > >- install a pressure gauge on each component protected > >- Pressureize to 5-10 psig only > >A good website to visit is : > >http://www.cortecvci.com/index2.php > >They have an extensive preservation manual that mentions >nirtogen blanketing as well as use of corrosion inhibitors, >which the company sells.. > >I believe that this topic is important enough to consider a >seperate part of the bulletin board dedicated to it.... > >Many millions of dollars can hang in the balance when the >method of preserving/mothballing is decided... > >My opinion only > >MJCronin