T A N K CARS By American Car and Foundry Company RICHARD W. LAHEY, Packaging Editor
Vna umicled tanJk-ca* tanm had* pmomd t* ia a oainaala canttiintian ta éaja tnanépontatio+t oj Âep*2ictc*é4é pàodnoU. rfjta* {OM* naa*A o£ trial in conuna^dal ttûMépo* tat/a*, i t utaè, apptavad tup tUa y.G.C. ^ / i / i > # e >>ecaW ^ ^ U ^ ^ i ^ , o ^ ii4^7 o 4 tka ά β α ϋ α / ^ Μ ^ α£ axprntiancm obtained éinca apf*UHMclf cancluéiualu dmmonatnataA îtê. éétpatiatity A * addition, nmaitatmaticm oaèté, a*o Iowa* and iakuiaa Ufa id inctmo&ed 9t il intotoaitinf ta nota tkcUvtftk *imtimttêaomé. aùont 70 pa% cant at tUa é fiesta fA at Hua étael plota **v obtained, te/file wit/t wetd+d jointe. tUa épaeifccatiané, paatnit aaiinta a joint o^facimncéf o£ 90 pma oant in calcnlatina tUa on+étinf at*e?nftA o£ tho tanL· Waldad tank* can Δα UnmduUtU -AulUtan o* load mo*o aaliln and fptota tliaotittalif AacGadc it ia uiUicawtp^tcpatift ta coua% tit'tt ftaadé and tna omvdappmd plata jaintl of tA$ *iimtad tannéNESTLED
in the Alleghenies, in the quiet
Pennsylvania town of Milton, is the tank-car shop of the American Car and Foundry Co. The peaceful aspect of the surroundings is no indication of the beehive of activity which prevails within this plant. I t has required all the ingenuity of the management and unbelievable efforts of the workers to meet the demands of the war for tank cars, storage tanks, process tanks, bubble towers, etc. One cannot help but be impressed with the efficient and confident spirit that pervades this organization. They have
e^very right to their pride in their production record, the quality of their product, amd particularly the all-welded tank-car teuiks which they confidently recommend &s safe, economical, and efficient. Production averages over 100 tank c=ara p e r week. They fabricate high and low pressure, welded and riveted as well i t s insulated tank-car tanks. The successful record of the all-welded tank-car tanks has led to their approval h*y t h e I.C.C. and hearty acceptance by chemical shippers. A.C.F. has had a leading part in this important develop-
Fitting parts of tank &«*thcr in preparation for welding, called "fitting up"
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ment. A complete welding technique has been developed, equipment for accurate and efficient preparation of plates has been built, clever jigs and handling equipment by which the tank parts are firmly held in place and properly positioned for weld-, ing have been developed, and highly skilled men have been «trained. This h a s been accomplished by establishing a comprehensive control of all the many details that enter into good welding practice. The most important single factor is t h e replacement of hand operations with automatically controlled machines. Double-Plate Planer A double-plate planer is the outstanding example of these accomplishments. I n one operation, this machine cuts to width, trues the noses, and bevels the upper a n d lower edges of two parallel sides of t h e plate. There are 15 cutting tools on each side of this planer which make 3 different cuts a t one pass on each edge of the plate. The planer is adjustable to cut plates from a minimum of 48 inches to a maximum of 163 inches in width and dimensions a r e controlled to the unbelievable maximum; tolerance of 0.002 inch. The importance; of this exact control of dimensions is] evident in the "fitting u p " and welding processes. The volume required for efficient operation of the planer has been obtained through the ability of American Car a n d Foundry Co. to standardize diameters of a goodly percentage of its tank production. Other methods in use for squaring and beveling plate edges include t h e single planer and cutting with gas torches. Both methods require hand setting, which is less accurate than the automatically set double-plate planer. Plates for high-pressure tanks a r e then shaped into cylinders in drop end rolls. The tanks are formed from three of these cylinders. On the other hand, t h e lowpressure tanks are fabricated from, three plates, each of which extends over t h e entire length of the tank and covers about one third of the circumference. These latter plates are shaped on long, solidhead, pyramid rolls. The edges are m e chanically précrimped prior to rolling. Tank heads are formed of plates t h a t are shaped by hot pressing or drawing in an 1,100-ton hydraulic press. I n this operation, the male section of t h e die AND
ENGINEERING
NEWS
pushes the plate through a ring die (female section). The plates are thus accurately shaped, dimensions are uniform, and the operation is performed with a minimum distortion of metal. The flanged ends are cut with a gas torch to proper depth and the edges beveled by chipping. By this pressing method of fabricating tank heads, it is possible to control dimensions more closely than when heads are spun. Here again, close control is of vital impor tance for the method of welding in use at this shop. Prior to welding, the shaped pieces must be carefully fitted together. The noses of adjacent plates for each circum ferential and longitudinal joint are butted to make an exact fit, by means of wire cables and take-up jacks. When plates are positioned, they are held firmly by welding several fitting bars on the ex terior surface across each outside joint. The importance of the edge preparations becomes evident in this operator*. Plates which are not held to exact dimensions cannot be brought into contact along the entire length of the joint. Any joint showing daylight through to the inside of the shell is closed with back ing wire placed in the outside groove. This prevents penetration of the inside weld to the outside groove. If the weld does penetrate, there is danger of its burn ing through and burning a hole in the plates. Weldins the Tanks The "Unionmelt" submerged arc fusion welding system is used on all joints of the tank shell. This system automatically controls feed of welding wire, amount of flux: fiisc&^time or speed of welding, and degree of heat. An accurate technique has been developed as a result of years of experience. The most important con tributing factor to the high degree of welding accuracy which has been attained is the choice of automatic equipment and controls. The interior welds are made with, welding heads mounted on a carrier called a "monitor". This monitor travels
X-raying the welded seam
This double-edge planer, th« only machine οί its type in existence, weishs 343,000 pounds
along the joint at a constant speed, guided automatically by a wheel that travels in the groove. The operator adjusts the heat as required by the variations in the amount of weld metal which must be de posited due to the width of the V formed by the abutting plates. Circumferential welds are made by rotating the tank shell; the monitor traveling at the same speed in the opposite direction maintains a set position at the bottom of the shell. Longitudinal seams are welded last, in order that all weld joints can be effec tively overlapped. Before the fitting bars are removed to permit the exterior welding, the tank anchors for. fastening to the car underframe are fillet-welded to the exterior of the tank shell by the same Unionmelt method. The welding head is mounted
Welding en outside circumferential,scam
VOLUME
22,
NO.
24
DECEMBER
2.5,
1944
2193
of tiie welded joints of tanks built to I.C.C. or A.S.M.Iii.-U68 specifications is x-rayed to detect welding defects. If any defects are discovered, such unsatisfactory welds are effectively repaired by cutting out and rewelding. It requires from 80 to 110 x-ray pictures to cover all welds in a car tank. Each negative is numbered so that the photographed area on the tank can be immediately located. The detailed work of taking the pictures, developing them, and reading the negatives requires a well-equipped laboratory as well as the CONTINUED ON PAGE 2 2 2 7
ΐ?#%^^ This tank received a the insulation has been
bump at the circumferential end fern. The jacket to protect loose, but (he stem, although badly dented, remains tight
on a gantry for welding the tank anchors as well as all outside joints of the tank. The welding machine remains stationary and the shell is rotated for circumferential welds, while the gantry travels to weld the longitudinal seams. The inside and outside welding of tie tank shell, attachment of the anchors, the construction of the welded tank nozzle and protective housing, and attachment of the nozzle to the tank shell require approximately 325 lineal feet of welding. In all these critical welding operations, tie heat is set to penetrate almost through tie metal on both the inside and outside pass. There is, therefore, an overlap of the in side and outside welds. If the thickness of metal at the edges of the plate is not uniform, or if the noses of butting joints are not squarely against each other, the automatic control is replaced by the skill of the operator who must vary the heat of the weld to maintain the desired pene tration. This clearly illustrates the need for the accurate shaping of the edges which is so effectively accomplished by the double-plate planer. It also is evident that the "fitting up" or joining of the shaped plates must be carefully handled by highly skilled men. After the nozzle is fillet-welded to the top of the tank, the entire unit is stressrelieved in an accurately controlled oilfired furnace. Temperatures taken at four locations in the furnace are auto matically recorded to ensure compliance with annealing specifications. Testins Welded Tanks The testing procedure used for proving welded tanks provides positive proof of their quality. For instance, every inch 2194
Typical Unionmelt weld from tank shell
Welded tank car for liquefied petroleum 9es (Spec. I.C.C. 105 A — 3 0 0 W )
EOJîS'î.OK)'
sÎO EQUAliY SPACED HOltS WILL & TAP TOR I^STtf) BOLTS
'FILLET WELD
; FILLET WELD FUifTWCLD &RLLH YTCLD
Drawing o f "build-up nôzzk"
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Tank Cars (CONTINUED FROM PAGE 2 1 9 4 )
entire time of a sizable number of trained employees. The welding standards set b y A.C.F. require perfect welding. These standards are deliberately set above those required by any existing standard specifications to ensure tanks without fault. In addition to x-rays, certain physical tests of the welds are required by the specifications. Such tests include elonga tion, tensile across the weld, and tensile of the weld metal. These tests invariably show that the tensile strength and ductil ity of the weld metal are substantially above those of the parent metal. Specifications prescribe that the com pletely fabricated tanks must be hammertested while under hydrostatic pressure in addition to the hydrostatic pressure tests. According to employees of A . C F . , their welded tanks have never failed to pass these tests. The positive proof of satis factory welds obtained through x-rays precludes any failures in these tests. Tanks are then mounted on their under names and all valves, pipes, and other fittings including domes, dome covers, and protective housings if used, are a p plied. "^Insulation is then installed, if required, and the insulation jacket is ap plied in two pieces, each assembled on jigs and machine-welded. These two pieces are secured to the tank by^a bolted joint run ning lengthwise of the tank and about a t its horizontal center line. After gritblasting, the car is painted according to specifications.
construction will save approximately a ton in weight. T h e welded underframe is stronger, will last longer, and the main tenance cost will be lower. The welded underframe is assembled in sturdy jigs, which m a y be rotated so that all welds are positioned for the best type of welding. This construction uses the A.A.R. double Ζ bar center sill to replace the usual channel with cover plate of riveted construction. The striker and front draft lugs are fabricated from drop forgings and are welded to the center sill T h e bolster center filler as well as the rear draft lug constructions are of rolled steel securely welded together and to the center sill assembly. The bolster assembly is made of plates welded together a s well as welded to the center sill. The bolster cover plate is of substantial width and is curved to form cradles for the support ing wood slabbing. The use of welding not only reduces the amount of surface exposed to corrosion but eliminates all riveted joints which are corrosion breed ers. The construction is truly stream lined.
Vitamins in Cabbage That cabbage commonly contains approxi mately a thousand times as much vitamin C as vitamins Bi and B2 has been verified by studies at the U. S. Regional Vegetable Breeding Laboratory, Charleston, S. C.
Who Makes It? National Registry of Rare Chemi cals, ArmouT Research Foundation, 33rd, Federal, and Dearborn Sts., Chicago 16, 111., seeks: Norvaline Bromoacetyl
