VOL. I BOOK 4 CHAPTER I SECTION 3 additional sixteen tubes leaking. These were replaced, but after one week of operation this unit again developed serious tube leakage, The leaks all occurred in a pronounced encircling indentation of the tubes at a location immediately above the bottom tube sheet. In view of the conditions found, all units at Fred were opened and inspected. The condition found was fairly widespread and 1,716 defective tubes were replaced. As the stock of new tubing on hand was not sufficient to meet this situation and due to the urgency of placing these stills in good operating condition prior to the large influx of personnel for the operational phase, the Jobsite undertook to manufacture approximately five good tubes from six defective ones. The faulty end of the tube was cut off and a stub end was silver-soldered in its place. A jig was made at the Jobsite to insure proper alignment of the two parts of the tube. After this soldering, stress and acid tests were made on all soldered joints and all proved satisfactory, The raw feed on Site Fred was taken directly from the lagoon. At certain seasonal periods.sea moss accumulation was heavy. A dual strainer was installed in the supply line to the power and distillation plant on this site to prevent this moss from entering the plant salt water systems. However, some moss and sand did enter the system which was particularly harmful to the Climax Raw Feed Control Valves of the stills and required continual repair. The heat exchangers of the Cleaver Brooks 60E distillation units were con- structed with soft-soldered joints where the 2-1/8-inch tubes entered the tube headers. These joints developed leaks after approximately six months' operation. The Jobsite maintenance crews repaired these joints with silver solder as the leaks developed and thereby considerably prolonged their operating life. Difficulties were also experienced with the 5/8-inch tubes of these heat exchangers due to development of holes opposite the raw feed inlet. The Admi- ralty metal tubes originally installed in this assembly were replaced with CuproNickel tubes with little appreciable gain in tube life. In order that distillation units would not be kept out of operation due to failure of the heat exchangers, spare heat exchangers were maintained in readiness at all times. Heavy maintenance costs were incurred with the pumps used for the brine blow down. These pumps were manufactured principally from copper alloy materials, which did not withstand the corrosive action of the hot brine. A test was conducted in the use of a stainless steel pump, which was available at the Jobsite. This was highly successful, for after six months' operation no repairs to this pump were required. The costs of maintenance of the original pumps were analyzed and compared with the cost of their replacement with the stainless steel pump. The savings in maintenance costs by the use of the stainless steel pumps will amortize the investment in new pumps in approximately one year, and therefore a program of replacement of these pumps was initiated, 4-4