|
Inhibition of pitting corrosion of the copper sprinkler tubes by removing dissolved oxygen in water with
sodium sulfite was studied on the wet sprinkler systems operated in 258 household sites. First, air in the
sprinkler tubing was removed by vacuum pumping. The tube was then filled with sodium sulfite dissolved
in water. Sodium sulfite was very effective in maintaining a very low dissolved oxygen concentration in
water in the sprinkler tube for the observation period of six months. Water leakage from the copper sprinkler
tube was reduced significantly by using sodium sulfite. Both pitting corrosion process and pitting corrosion
inhibition mechanism were investigated by examining microscopical and structural aspects of corrosion pits
formed in failed copper sprinkler tube. Pitting corrosion was caused by pressurized air as well as sediments
such as sand particles in copper tubes through oxygen concentration cells. It was confirmed microscopically
that growth of corrosion pits was stopped by reducing dissolved oxygen concentration to a very level by
using sodium sulfite.
Keywords : pitting corrosion, copper sprinkler tube, sodium sulfite, corrosion inhibition, SEM
|
|
