>HI their > >Could any one hear about the calcareous scale that deposit >at the sea water heat exchange tubes? The tubes service is >sea water. If yes is their any to dissolve since we are >tried many chemical type but still very hard and plug the >tubes. > >David David, Assuming the heat exchangers are carbon steel, then inhibited HCl acid will be the chemical of choice. Ensure acid strength is manitained by the addition of more HCl during the cleaning process. Once the acid strength stops declining then you've done all you can. Also double check the solution does not become Fe saturated. Tubes that are blocked solid will be more difficult to clean since the flow will preferentially go through alternate tubes. Continual flow past the scale build-up is the key during acid cleans. It will be cheaper and more time efficient to hydro-blast clean the tubes which remain blocked. Regards, SGD.

Not using seawater would be the best option (probably not an option). It has huge numbers of dissolved solids. David, do you have a water treatment vender on-site? (GE Betz, Nalco, Baker Petrolite etc... - I found Baker Petrolite the best but it all comes down to the local people in each of the areas). They would be best able to take a close look at changing/adding a treatment program. Most likely they will recommend a dispersant polymer used to help stop the scale forming. Satellite dosing systems close to hot exchangers also works (if problematic enough). In addition, you can also install a DATS monitoring system which can be used to monitor heat exchange/fouling tendancies - (I have never used one - but I know of them). If your still desparate I can dig up some info Baker Petrolite gave me on seawater cooling systems. Let me know. SGD