STEEL CYLINDERS FOR COMPRESSED GAS CONTAINERS. 
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Steel Cylinders for Compressed Gas 
Containers. 
The manufacture of industrial gases, such as oxygen, carbon-dioxide, 
and anhydrous ammonia, has now reached considerable dimensions in 
Australia, and the Institute has received inquiries regarding processes 
for the manufacture of the steel cylinders which are used to contain 
such gases, but which are not at present made in the Commonwealth. 
The weldless cylinders used for this purpose are generally solid- 
drawn from a dise of steel. In drawing the cylinders, the process in 
England is a horizontal one, and the cylinders are drawn partly cold 
and partly hot. In America, the process is entirely hot—annealing 
taking place as necessary—the ram working vertically downwards. 
Tt is stated that this method has the great disadvantage that the scale 
formed causes fluting of the exterior surface of the cylinder, and it has 
recently been suggested that, if the ram were arranged to work upwards 
instead of downwards, the scale would not free itself automatically, and. 
would result in a polished eylinder, free from’ external fluting. The 
dies are lubricated with a mixture of graphite and tar. 
Generally speaking, the manufacture of cylinders is a simple 
problem from a practical point of view. Assuming that the plates are 
delivered in squares, the first operation is to shear off the corners so as 
to make a circular disc. This is done “hot” in one operation. The 
disc is then passed on to a series of vertical presses—three or four in 
number—in which, by means of die-plates and rams of gradually 
reducing diameter, it is reduced by stages to something like elongated 
thimble form. By that time, .the steel is too cold to work, and has 
probably become hardened somewhat as the result of the drawing-down 
process to which it has been subjected. It has therefore to be re-heated 
and annealed. In the re-heating process, care must be taken that the 
temperature of the furnace does not reach the “scale point.” Tn any 
case, the process should be carried out in a “ reducing” flame by means 
of producer gas and a properly regulated air supply. 
During the time that the partially drawn cylinders are being 
re-heated, the dies and rams of the presses are being changed. The 
partially drawn cylinders are then subjected to further pressing, the 
process being repeated until they have been drawn down to the required 
diameter. They are then allowed to cool. The next operation is to 
cut them to length. This is done with an ordinary parting tool, in a 
lathe. The cylinder is then inspected for obvious flaws, both inside and 
out, and the walls are callipered to establish uniformity of thickness, 
after which the cylinder is ready for “necking down”. 
The necking down of the cylinders is performed by a series of small 
steam hammers fitted with suitable swage blocks. For this process, 
it is not usual to heat more of the cylinder than is absolutely necessary, 
the butts remaining black. Swaging is carried out till the neck is 
closed.. No welding takes place, as the temperature is too low. The 
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