Carbonic acid is formed in steam systems when carbon dioxide reacts with water to form carbonic acid. An internet search using the query carbonic acid corrosion will pull up a lot of information to review. Carbonic acid corrosion is the final result of your piping being chemically dissolved and then being deposited in steam traps, condensate returns, and any other point where condensate can collect. The confirmation of carbonic acid corrosion is to check and see if the red brown material is magnetic. Place a small sample on a sheet of paper. Place a magnet under the paper. If the material follows the magnet as you move it around under the sheet of paper, you are looking at iron oxide which is the end result of carbonic acid corrosion. Put another way, you are looking at the results of carbonic acid attack on your expensive piping system.
Left untreated expect the following-
1. Many leaks in steam and condensate piping
2. Isolation and block valves which fail and will not close
3. Leaks in steam process equipment resulting in many repairs
4. Problems with pump seals failing
5. Valve packing failures
6. Screwed fitting which can not be taken apart
The solutions are simple-
1. Proper steam trap selection and application. Bucket traps and disc (thermodynamic) traps do not vent air unless equipped with an air vent. Use Float and Thermostatic traps.
2. Add traps at any points where condensate can form such as ahead of manual and automatic control valves and at low points in the system which can collect condensate.
Make sure your boiler room water softener is operating properly.
3. Make sure your deaerator is operating properly. Pressurized units should be operating at 225-227 degrees F and 5-7 psig. Atmospheric deaerators should be operating at 200-205 degrees F with extra care on proper boiler chemicals.