Pressure compound cylinder

The residual shear stress distribution in the assembled cylinders, prior to the appHcation of internal pressure, may be calculated, from pressure P, generated across the interface. The resulting shear stress distribution in the compound cylinder, when subjected to an internal pressure may be calculated from the sum of the residual stress distribution and that which would have been generated elastically in a simple cylinder of the same overall radius ratio as that of the compound cylinder. 

Figure 13.45. Stress distribution in a shrink-fitted compound cylinder (a) Due to shrinkage (h) Due to pressure...

Manning, W. R. D. (1947) Engineering 163 (May 2nd) 349. The design of compound cylinders for high pressure service. 

Fixed-Roof Tanks. The effect of internal pressure on plate structures, including tanks and pressure vessels, is important to tank design. If a flat plate is subjected to pressure on one side, it must be made quite thick to resist bending or deformation. A shallow cone-roof deck on a tank approximates a flat surface and is typically built of 3/ 16-in. (4.76-mm) thick steel (Fig. 4a). This is unable to withstand more than a few inches of water column pressure. The larger the tank, the more severe the effect of pressure on the structure. As pressure increases, the practicality of fabrication practice and costs force the tank builder to use shapes more suitable for internal pressure. The cylinder is an economic and easily fabricated shape for pressure containment. Indeed, almost all large tanks are cylindrical. The problem, however, is that the ends must be closed. The relatively flat roofs and bottoms or closures of tanks do not lend themselves to much internal pressure. As internal pressure increases, tank builders use roof domes or spheres. The spherical tank is the most economic shape for internal pressure storage in terms of required thickness, but it is generally more difficult to fabricate than a dome- or umbrella-roof tank because of its compound curvature. 

Easier to achieve than the autofrettage in order to increase the yield pressure is the construction of a compound cylinder. Here a second cylinder (or jacket)... 

CompoundShrinka.g e. In its simplest form (Fig. 8a) compound shrinkage consists of machining the inner radius of an outer component I, (Qp so that it is smaller than the outer radius of an inner component II, The difference between the two is known as the radial interference 5. To assemble the cylinders, outer component I is heated and/or inner component II cooled so that the outer component can be sHpped over the inner as shown in Figure 8b. When the temperature of the assembly returns to ambient, a compressive stress (pressure) is generated across the interface which simultaneously compresses the inner and expands the outer component and, in so doing, displaces radius (r/j by Uj and radius ( jj by U, Unfortunately, it is difficult to carry out this operation without setting up stresses in the axial direction (32). 

Chemica.1 Properties. Reviews of carbonyl sulfide chemistry are available (18,23,24). Carbonyl sulfide is a stable compound and can be stored under pressure ia steel cylinders as compressed gas ia equiUbrium with Hquid. At ca 600°C carbonyl sulfide disproportionates to carbon dioxide and carbon disulfide at ca 900°C it dissociates to carbon monoxide and sulfur. It bums with a blue flame to carbon dioxide and sulfur dioxide. Carbonyl sulfide reacts... 

Highly irritating and poisonous Very soluble in water. Liquid liberates heat as it dissolves in water. The entrapment of water in an anhydrous hydrogen fluoride cylinder can cause rapid generation of heat and pressure which can lead to an explosion. Containers should never be heated to >52°C. A liquid hydrogen fluoride spill area should not be entered unless protective clothing (impervious to the compound) and a self-contained gas mask are worn Fumes in air... 

Tandem Compound high and low pressure cylinder on same centerline usually requires 80 psi or greater steam to be economical. 

A mixture of propyne containing 30% of propadiene under a pressure of 3.5 bar was accidentally brought to 95°C at a spot in the storage cylinder. It then detonated. Commercial propyne becomes dangerous at 3.4 bar and at 20°C. It is lowered to 2.1 bar if the compound is heated to 120°C. Some authors think that the stability of the commercial mixture is close to that of ethylene. 

Modem designs fitted with non-retum valves through which the plasticised rubber compound passes into the injection cylinder portion are capable of giving precise shot volume. The non-retum valve is activated by the injection pressure. The injection ram/non-retum valve unit ensures complete purging of the injection chamber. 

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