TECHNOLOGY
Tanker Corrosion Costs $ 5 0 , 0 0 0 Control seems most promising with use of inhibitors such as oil-soluble organic compounds N E W Y O R K . - E s t i m a t e d corrosion bill for a fleet of 2 0 tankers is $1 million p e r year, says R. W . Moore of Socony Vacuum Oil. This averages out to $50,0O0 p e r ship p e r year, h e told the N e w York Section Meeting-in-Miniature. Control of tanker corrosion has b e e n attempted with coatings, cathodic pro tection, dehumidification, and corrosion inhibitors. The latter seem to be most promising. Internal corrosion in tankers varies greatly with the environment of the ship, says Moore. T r a d e route, type of cargo, ballasting, and frequency of cleaning a r e all important factors. Tankers carry two types of cargoes. Those in t h e "clean trade" carry light products like gasoline and kerosine, while the "dirty trade" is the haulage of heavy fuel oil, lubricating oil, and c r u d e . With t h e light products, m e t a l surfaces r e m a i n clean and are t h u s more readily attacked b y the salt w a t e r used for ballast and cleaning, as well a s t h e d a m p salt atmosphere at sea. I n t h e dirty t r a d e , inner surfaces of t a n k e r s a r e coated with an oily film which, helps to protect against corrosion. T h e Butterworth machine, used for cleaning tanks, consists of two nozzles mounted on a more or less universal joint. This apparatus is lowered into a tank and all parts of t h e inside of t h e tank are thoroughly flushed with hot s e a water under high pressure. This process removes any loose scale or rust, exposing fresh metal to the ravages of •corrosion. T h e hot sea water (often as "high as 180° F . ) , also promotes corro sion. Fresh water vessels are corroded only to a slight extent, and Moore r e p o r t s that fresh water tankers a n d "barges in predominately clean t r a d e h a v e been known to need no repairs after 14 years. Corrosion in tankers which make a delivery a n d then an empty return trip is manifest first by a layer of hard, rusty scale covering t h e entire metal struc t u r e . The rusty scale grows thicker with t i m e , and often falls loose in large slabs. S h i p s in this type of service usually b a v e several tanks filled with salt water "ballast o n the return trip. Corrosion fatigue, eventually result ing i n failure by cracking, is a result of t h e corrosive environment in the tanks and the stresses and strains which a vessel undergoes i n heavy seas. F a t i g u e failures, referred to in the industry as 816
"hard spots," a r e localized rather than general all-over wastage. Vessels carrying crude containing large amounts of active sulfur may be subject to severe corrosion. "Ships in the dirty trade, particularly those carry ing Middle East crude, are subject t o a severe type of pitting action/* says Moore. Especially serious damage, re sulting in early leaks which must be re paired, occurs w h e n crudes settle out a thick waxy sludge, which traps drops of water in place on horizontal sur faces. Natural corrosion process starts a pit underneath these drops of salt water. T h e center of t h e p i t becomes anodic to the surrounding area and growth of the pit is promoted.
Chief drawback to the practical use of coatings such as paints a n d metallic sprays is t h e expense of application. To be satisfactory t h e coatings m u s t be applied to clean, bare metal, b u t the process of removing all old rust from all die intricate places in a ship's structure is prohibitively expensive. Cathodic protection b y the use of magnesium anodes has b e e n used with some success. Expense of installation and of the renewal of the anodes is discouraging, and protection is attained only in the ballasted tank. Dehumidifi cation requires t h e operation and main tenance of a large a m o u n t of equip ment, b u t h a s p r o v e d helpful. Corrosion inhibitors are easily a p plied, and oil soluble organic inhibi tors of the film forming or polar t y p e have resulted in a 5 0 % reduction in corrosion in some instances. W a t e r sol uble inhibitors (such as sodium nitrite, phosphates, and alkaline solutions) have been tried with moderate success, says Moore.
Atomic Locomotive: H o w Soon? Using uranyl sulfate in water as fuel for modified w a t e r boiler reactor, engine could develop 7 0 0 0 hp. ρ υ τ of Salt Lake City comes latest the road" w o u l d b e t h e same as for ^ ^ proposal for p u t t i n g atoms to use Diesel locos. ful work. Proposal, complete with de As with other proposals for peace sign and cost information, is for an time harnessing of atomic power, h o w atomic-powered locomotive. Designer soon atomic locomotives come r o u n d Lyle B. Borst, University of Utah, be the b e n d d e p e n d s on cost being com lieves his locomotive could b e competi petitive with present engines. Borst esti tive with today's Diesel, at least under mates cost for one of his locomotives to certain conditions of use. b e about $1.2 million, a b o u t twice t h a t As described to railroad officials, the of a Diesel. More important, however, engine would b e similar in outward ap are operating costs, and here w h a t pearance to today's Diesel. It would would h a v e to b e p a i d for U 2 3 5 enters develop 7000 h p . , c o m p a r a b l e to a four- the picture. W h a t the Government is unit Diesel, a n d its w e i g h t would be paying for its U 2 3 5 is k n o w n to only a somewhat less—700,000 p o u n d s con select few. However, these are t h e costs Borst estimates could b e paid for fuel trasted to 900,000. Final drive would (fuel loading, discharging of spent he b y electric motors, b u t there the fuel, disposal of waste) under different similarities e n d . A modified water boiler, similar to operating conditions. If the unit were Los Alamos's water boiler research re used in average service—short hauls, actor, would provide h e a t . Reactor long h a u l s ; heavy hauls, light h a u l s fuel would b e uranyl sulfate in water. then atomic p o w e r could b e competi Borst plans n o secondary heat transfer tive at a fuel cost of less than $7000 medium such as liquid sodium, w o u l d per p o u n d ( a n d Borst figures a p o u n d exchange heat to water a n d make steam of fuel would be a d d e d every few within the reactor. T h e r e , w a t e r would months ). be converted to steam ( 2 5 0 pounds p e r But it is more t h a n likely t h a t such square inch, with a difference in tem a premium unit as an atomic locomo perature between fuel a n d water of 50° tive w o u l d get more than average serv to 60° F . ) . Remainder of the p o w e r ice. If it got as m u c h as 5 0 % more train would b e : turbine, generator, a n d than the U . S. average, Borst believes electric motors. O p e r a t i n g crew "on it could operate on a fuel cost of $ 1 1 , CHEMICAL
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