Blasting, painting and coating irrespective of weather conditions

NTPC
Bilaspur, Chattisgarh

Background

NTPC Koldam Hydro Power Project is on river Satluj in distt. Bilaspur, Himachal Pradesh. Koldam, the flagship Hydro Power Project of NTPC, has an installed capacity of 800 MW ( 4×200 MW) and provides the much needed peaking capacity to the Northern grid and annually generates 3054 GWh electricity. 

Problems

As we know that when a dam is in operational, the water flows at a very high speed/pressure to the turbine through the penstock. During this process, some silt also comes along with the water. This slit was causing high friction inside the spiral casing. To control this loss, NTPC decided to apply 500 micron ceramic coating inside the casing. 

But, during the blasting and coating job if relative humidity is more than 50% then there are chances of flash rust on the surface as the wet bulb and dry bulb become the same and 5OF or 3OC difference is not maintained between the dew point and surface body as per the standard specification of NACE and SSPC10. During the job done at NTPC koldam the relative humidity was 60%.

Our Solution

TDS provided desiccant based Dehumidification system to control relative humidity during the blasting and coating job which reduced the relative humidity from 60% to 35%.  TDS also installed heater banks as the temperature was very low inside the spiral casing area which helped to avoid condensation formation on the spiral casing.

Benefits

  • Condensation did not take place on the surface where the blasting and coating job was done
  • Proper ventilation and temperature control were provided inside the penstock and spiral casing.during the entire job
  • Coating and painting work was finished before scheduled time

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