Pressure vessels upper section

Another aspect to be noted is that the ASME Boiler and Pressure Vessel Code Section II, where specifications of materials are provided, changed the specification of 9Cr-lMo-V in 2006 to reflect the field experience of the fossil industry. As a result, the upper limit of A1 was lowered, and an upper limit was newly introduced for Ti and Zr. There is a possibility that more changes would be made ujx)n the decision of the Code committee. 

In the petroleum industry, mixed-media filters are usually of the pressure type. Either vertical or horizontal pressure vessels are used. Fig. 5 provides a cross-section of a typical horizontal filter system using mixed media. Note that a pipe lateral-underdrain system is used with silica gravel, providing support for the filter bed. An all-water backwash is used typically the backwash flow rate b 15 to 20 gal/min/sq ft, depending upon the water temperature. A surface wash device b used to aid in the cleaning cycle. It provides increased agitation of the upper portion of the filter bed, improving backwash efficiency. 

Maximum allowable working pressure (MAWP) The maximum permissible gauge pressure of a vessel in its operating position at a designated temperature. The pressure is based on calculations for each element in a vessel, using nominal thickness exclusive of additional metal thickness allowed for corrosion. The MAWP is the basis for the upper limit of pressure setting of the safety relief devices that protect the vessel (see Section 3.6). 

J.2.4 A slot measuring 22mm wide x 46mm deep is machined in one side of both the upper section and the base section such that when the pressure vessel assembly is lowered, firing plug end first, into the box support, the side-arm is accommodated in this slot. Packing pieces of steel 30mm wide and 6mm thick are welded to the lower... 

A cross-section of the reactor pressure vessel together with that of the containment vessel is shown in Fig. 3. Effective layout of the primary components makes the reactor compact by installing the most of components inside the vessel The core locates in the lower part, the steam generator in the middle part, the CRDMs and pressurizer in the upper part inside of the reactor pressure vessel, and the primary coolant pumps are connected directly to the flange of this vessel. Major specifications of the core, the CRDMs, the SGs, the pressurizer, and the primary coolant pumps are shown in Table 1. 

The RPV consists of an upper head and a vessel. It is designed and manufactured in accordance with section III of the ASME Boiler and Pressure Vessel Code. The vessel and the upper head are made of low alloy steel and fabricated from forged sections. All the inner surface of the RPV in contact with reactor coolant is clad with stainless steel. 

The RCGV function provides a safety-related means of venting remotely from the control room, non-condensible gases from the reactor vessel upper head and the pressurizer steam space during post-accident conditions (see CESSAR-DC, Section 6.7.1.2.1). Positive indication of vent isolation valve position is displayed in the control room (see CESSAR-DC, Section 7.5, Table 7.5-2). 

The two first-mentioned reactions of CsOH are of little significance in a reactor accident, since only small amounts of these materials are present in the primary circuit outside the reactor pressure vessel. The reaction with stainless steel surfaces, however, may lead to significant retention of cesium in the reactor pressure vessel, in particular at the upper core structural materials there will be a more detailed discussion of these reactions in the context of severe reactor accidents (see Section 7.3.2.). 

The fluidised bed reactor is a vertical pressure vessel with a total height of up to 40 m. A fluidised bed of polymer particles in gaseous ethylene is maintained by a recycle compressor. The ethylene recycling gas enters the reactor through a distributor plate at the bottom to achieve an even gas flow over the entire cross-section and to hold the particles when the gas flow is turned off. In the characteristically conical upper part of the reactor, the gas velocity decreases with the increasing diameter of the reactor to keep the particles in the fluidised bed. The gas leaves the reactor at the top. It is cleaned from entrained particles by a eyelone, the reaction heat is removed by a recycle gas cooler and the gas is then routed back to the bottom reactor inlet. 

As shown previously (Section 14.7), thermal transpiration or thermomole-cular flow arises when gas is contained in two vessels at equal pressures but different temperatures and a connection is made between the vessels. A vacuum microbalance represents just such a system. The long tube surrounding the hang-down wire separates the sample, immersed in the coolant bath from the warm upper portion of the apparatus. With vacuum microbalances the effects of thermal transpiration are further exacerbated by the temperature gradient along the hang-down wire. 

The apparatus used is represented in Fig. 376 in vertical section taken through the centre of the apparatus. It consists of a cast-iron cistern, A, having semicircular ends, and open on the upper side at one end of it is a cylindrical vessel, b, with hemispherical ends. This vessel is of considerable strength, and ahould be capable of withstanding a pressure of five... 

In many practical cases, the conditions for criticality described in the previous sections are only necessary to ensure safe operation. Such conditions do not guarantee, indeed, that the maximum allowable temperature in the reactor, Tma, is not exceeded. For instance, this upper temperature limit can be imposed, in liquid systems, by the bubble point of the reacting solution or by the decomposition temperature of some compounds in it, or, in gaseous systems, by the maximum internal pressure the vessel can comply with. 

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