Laboratory studies have shown that ammonia in concentrations as low as 0.4 percent in systems containing 2 percent hydrogen sulfide by volume is effective in controlling vapor zone corrosion.*** Results of experimental field work with 55,000-barrel tanks showed that the efficiency of protection gradually increased from 16 percent when an inhibitor injection rate of 1.4 pounds per tank per day was employed to almost complete protection when 12 to 15 pounds per day were added to the tank vapor zone. The uninhibited corrosion rate measured simultaneously in tanks in similar service averaged 273 mdd, or 0.053 ipy, for the entire test period.
The Interstate Oil Pipe Line Company is now using ammonia in treating eight tanks at three pipe line stations. Three tanks at Magnolia Station in southern Arkansas and two at Moore Station in northern Louisiana are receiving ammonia from bulk storage. The three remaining tanks under treatment are at the Yellowstone Station near Billings, Montana. Ammonia usage is economical and is equally effective in both areas despite the great differences in climatic conditions.
