Vessels, process heads

The bolting material for the reactor vessel closure head is fabricated from SA 540, B23 or B24, Class III material. This material conforms to the requirements of 10 CFR 50, Appendix G and the intent of Regulatory Guide 1.65, "Materials and Inspections for Reactor Vessel Closure Studs." Nondestructive examination will be performed according to Subarticle NB-2580 of Section III of the ASME Code, during the manufacturing process. 

For the AB sequence, events occur very fast. Clad oxidation starts at 344s into the accident, while gap release starts at 382 s and core degradation at 693 s. The whole process ends with the vessel lower head failure at 10121s. 

Vessel heads can be made from explosion-bonded clads, either by conventional cold- or by hot-forming techniques. The latter involves thermal exposure and is equivalent in effect to a heat treatment. The backing metal properties, bond continuity, and bond strength are guaranteed to the same specifications as the composite from which the head is formed. AppHcations such as chemical-process vessels and transition joints represent approximately 90% of the industrial use of explosion cladding. 

The heatable areas of the diyer are the vessel wall and the screw. The diyer makes maximum use of the product-heated areas—the filling volume of the vessel (up to the knuckle of the dished head) is the usable product loading. The top cover of the vessel is easily heated by either a half-pipe coil or heat tracing, which ensures that no vapor condensation will occur in the process area. In addition to the conical vessel heated area, heating the screw effectively increases the heat exchange area by 15-30 percent. This is accomphshed via rotary joints at the base of the screw. The screw can be neated with the same... 

For vaporAiquid separators there is often a liquid residence (holdup) time required for process surge. Tables 1, 2, and 3 give various rules of thumb for approximate work. The vessel design method in this chapter under the Vapor/Liquid Calculation Method heading blends the required liquid surge with the required vapor space to obtain the total separator volume. Finally, a check is made to see if the provided liquid surge allow s time for any entrained water to settle. 

Process flow diagrams are more complex and show all main flow streams including valves to enhance the understanding of the process as well as pressures and temperatures on all feed and product lines within all major vessels and in and out of headers and heat exchangers, and points of pressure and temperature control. Also, information on construction materials, pump capacities and pressure heads, compressor horsepower, and vessel design pressures and temperatures are shown when necessary for clarity. In addition, process flow diagrams usually show major components of control loops along with key utilities. 

A shell of revolution is the form swept out by a line or curve rotated about an axis. (A solid of revolution is formed by rotating an area about an axis.) Most process vessels are made up from shells of revolution cylindrical and conical sections and hemispherical, ellipsoidal and torispherical heads Figure 13.3. 

Process vessels are built up from preformed parts cylinders, heads, and fittings, joined by fusion welding. Riveted construction was used extensively in the past (prior to the 1940s) but is now rarely seen. 

Absorption of a gas in a liquid. Vessels have collapsed when ammonia vapor from the head space dissolved in water within the vessel (Lees, Loss Prevention in the Process Industries, 2d ed., But-terworths, London, 1996). A similar potential should be considered for HCl and water. 

In the past, filament-wound parts consisted primarily of axisymmetric cylinders, spheres and domed vessels. Several manufacturing techniques have been developed that allow more complex shapes and curvatures while maintaining the cost effectiveness associated with process automation [52], These methods have emerged because of advances in programming software. These advances enable precise positioning of the moving head and allow real-time simulation of fiber paths. 

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