Pressure vessels requirements

Most pressure vessels require rupture disks for which designs are specified according to ASME or other international standards codes. They may protect from either overpressure or vacuum conditions. It is composed of a membrane that will instantaneously fail (within milUseconds) at a specified differenfial pressure. Figure 4.18 shows a horizontal vessel that failed because it was poorly vented or due to a failure in the rupture disk. 

A dual-stack cell design that enclosed two stacks within the same pressure vessel was developed to reduce the number of pressure vessels required in some power systems. This conflguration was termed a common pressure vessel. These powered the Iridium constellation of 88 satellites (98 satellites, including orbital spares). While these batteries have functioned reasonably well, there are some difficulties in maintaining all the cells at a similar state of charge. However, these single pressure vessel batteries continue to perform well in orbit. 

Vendor must possess valid certificates for fabrication of pressure vessels (required by statutory authorities)... 

It should be noted that the term, "Firebox Quality," as applied In ASm A-212 Grade B formulation. Is a grade terminology that Imposes rigid controls and close supervision of mill practices The term denotes a material intended for application In pressure vessels required to withstand repeated thermal and mechanical shock. A 212, Grade B, Firebox Quality Is superior to either... 

Influence of process type on pressure vessel requirements... 

The carrying out of pressure and leakage tests also requires suitable preparation. Since the vessels-as long as pressure vessels are concerned-have already been subjected to a pressure test in the manufacturer s works, pressure tests are generally limited to the assembled pipes. In certain cases, however the Technical Regulation on Pressure Vessels requires a pressure test of the apparatus in a built-in state /4.18/. 

Cladding can also be accomplished by other methods such as arc or gas welding in which relatively thick layers of weld metal are deposited either by manual or machine methods on surfaces. The interior of pulp digesters or other pressure vessels requiring an alloy composition to resist the chemical conditions can be constructed in this manner. 

Until very recently liquid hydrogen has been in limited supply and its use has been restricted to small quantities at any one time. The transfer of small quantities of liquid from storage dewars to the use points has been effected by pressurization of the dewar with hydrogen or helium gas or by the use of specially designed centrifugal pumps. As the use of liquid hydrogen for missiles and for other activities increases, the quantity of gas required to pressurize and transfer the liquid from a dewar becomes large audits cost and that of the pressure vessel required become important considerations in the selection of the type of transfer system to be used. 

---