Forums are temporarily disabled while we are working on a new login procedure.

When migrating the old forums over to our new forums we were unable to retain the identity of the authors, so the old posts will show up as "anonymous". All NEW posts will show up credited to their authors. So please participate and share knowledge just as you have in the past.

You must log in if you are an existing user or register if you are a new user in order to contribute to the discussions.

Discussion Forums - The Hendrix Group
HomeHomeDiscussionsDiscussionsGeneral Corrosi...General Corrosi...corrosion in steam turbine rotorcorrosion in steam turbine rotor
New Post
8/29/2006 9:00 AM
In our Process Plant we have a Steam Turbine which works at 11000 rpm and by counter-pressure. This Plant stopped working since July 2005, due to high Natural Gas Price, and preventative on September, 2005 this Turbine had been checked out and it was found strong corrosion that had never seen before ( 28 years). Our oxygen levels are strictly controlled (less than 20ppb) and it has been always like that. Phospate residual levels are on average 0.8 ppm. The Temperature and the Steam Pressure have maintained their design values as well. Exhaust Steam Pressure 3 bar Exhaust Steam Temperature 206%C2°C We consider the following as the possible causes: The Turbine had been in a humid environment for about two months. ( it was closed) A change of the oxygen scavenger replacing Hydrazine. It has been used since April 2005. This compound contains cycle hexylamine, methoxy propylamine, diethyl hydroxylamine. This complex generates quelates which can be seen (black color) in the corrosion showed. In the oxide deposits it was sensed a strong Ammonia smell. There are white color salt deposits not incrusted in each of the Turbine stages From previous event main corrective actions derived from root cause analysis conducted here were: Very strict control in oxygen scavenger addition, returned to hydrazine, less than 50 ppb residual oxygen. Turbine drying and blanketing immediately after shooting down. Ammonia monitoring in process condensate between normal limits. Vibrations monitoring between normal parameters. Controlling temperature and pressure of exhaust steam (preventing, at least trying, early condensation phenomenon) Controlling de-mineralized water quality, according with attached file. we are having serious doubts about the possibility of being affected by a catalyst renewal (exchanged in January, 2005) in our natural gas Reformer, here process condensate is recovered and re-injected in steam circuit, according to design procedure, that%E2%80™s why we are thinking in this situation as a possible source of the problem. The difference between normal conditions (before catalyst exchange) and current conditions is a rise in ammonia content in such condensate. nickel is the main compound in the catalyst , and the only BIG difference between this one and the older catalyst, during the last 28 years vs current problematic is catalyst supplier change.
HomeHomeDiscussionsDiscussionsGeneral Corrosi...General Corrosi...corrosion in steam turbine rotorcorrosion in steam turbine rotor



With a little delay, our Calculation of Ammonium Salt Deposition more
Our sulfidic corrosion calculators are now available at more

Stay Current

Sign up for our quarterly newsletter

covering updates on corrosion

Sign Up