Support structure

There are various methods that are used in the support structures of pressure vessels, as outlined below. 

One of the most common methods of supporting vertical pressure vessels is by means of a rolled cylindrical or conical shell called a skirt. The. skirt can be either lap-, fillet-, or butt-welded directly to the vessel. This method of support is attractive from the designer s standpoint because it minimizes the local stresses at the point of attachment, and the direct load is uniformly distributed over the entire circumference. The use of conical skirts is more expensive from a fabrication standpoint, and unnecessary for most design situations. 

The critical line in the skirt support is the weld attaching the vessel to the skirt. This weld, in addition to transmitting the overall weight and overturning moments, must also resist the thermal and bending stresses due to the temperature drop in the skirt. The thinner the skirt, the better it is able to adjust to temperature variations. A hot box design is used for elevated temperatures to minimize discontinuity stresses at the juncture by maintaining a uniform temperature in 

There are various methods of making the attachment weld of the skirt to the shell. The preferred method is the one in which the center line of the shell and skirt coincide. This method will minimize stresses at the juncture. Probably file most common method, however, is to make file OD of the skirt match the OD of the shell. Other methods of attachment include lapwelding, pedestal type, or a shear ring arrangement. The joint efficiency of the attachment weld also varies by the method of attachment and is usually the governing factor in determining the skirt thickness. This weld may be subject to cracking in severe cyclic service. 

The most common governing conditions for determining the thickness of the skirt are as follows  

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Pipe hangers are essentially frictionless but require taller pipe-support structures which cost more than structures on which pipe is laicT Devices that reduce friction between laid pipe snbjec t to thermal movement and its supports are used to accomplish the following ... 

Tube bundles are designed to be rigid and self-contained and are mounted so that they expand indepeudently of the supporting structure. 

Design Features There are three classes of thickeners, each differentiated by its drive mechanism (1) bridge-supported, (2) center-column supported, and (3) traction drives. The diameter of the tank will range from 2 to 150 m (6.5 to 492 ft), and the support structure often is related to the size required. These classes are described in detail in the subsection Components and Accessories for Sedimentation Units. ... 

Sedimentation systems consist of a collection of components, each of which can be supplied in a number of variations. The basic components are the same, whether the system is for thickening or clarifying tank, drive-support structure, drive unit and lifting device, rake structure, feedwell, overflow arrangement, underflow arrangement, instrumentation, and flocculation facilities. 

Drive-Support Structures There are three basic drive mechanisms. These are (1) the bridge-supported mechanism, (2) the center-... 

Rotary Drum Filters The rotaiy drum filter is the most widely used of the continuous filters. There are many design variations, including operation as either a pressure filter or a vacuum filter. The major difference between designs is in the technique for cake discharge, to be discussed later. All the alternatives are characterized by a horizontal-axis drum covered on the cylindrical portion by filter medium over a grid support structure to allow drainage to manifolds. Basic materials of construc tion may be metals or plastics. Sizes (in terms of filter areas) range from 0.37 to 186 m (4 to 2000 ft ). 

The advantages of this type are low headroom and low power requirement. The disadvantages are the high cost of maintenance of the screen and the supporting structure owing to vibration and low capacity compared with inchned high-speed vibrating screens. 

The peak value of the asymmetry is considered to determine the electrodynamic stresses 10 design the meehanieal system and the supporting structure for the current-carrying components. 

We discuss in detail in Chapter 28, the procedure to design a bus system, including its mounting and supporting structure and hardware for a required fault level. 

The hollow fine fiber configuration (refer to Figure 51) consists of a bundle of porous hollow fine fibers. These fibers are externally coated with the actual membrane and form the support structure for it. Both ends of each fiber are set in a single epoxy tube sheet, which includes an 0-ring seal to match the inside diameter of the pressure vessel. 

An enclosure is usually an air-supported structure which permits the collection and treatment of gaseous wastes produced by surface impoundments. Enclosures are susceptible to wind damage and can be harmed by the wastes they cover. Subject to these limitations, control effectiveness approaches 100 percent (University of Arkansas and Louisiana State University, 1985). 

From the viewpoint of accommodation to the filter-supporting structure, some cloths cannot be used, even though the filtering characteristics are excellent. For rotary drum filters, for example, the cloth is pressed onto the drum by the caulking method, which uses cords that pass over the drum. In this case, the closely woven cloths manufactured from monofilament polyethylene or polypropylene fiber are less desirable than more flexible cloths of polyfilament fibers or staple cloths. 

Information normally excluded from P I diagrams includes electrical wiring (normally separate electrical diagrams must be consulted), nonprocess equipment (e.g., hoist, support structures, foundations, etc.) and scale drawings of individual components. 

Melting and slumping of the fuel onto the lower core support structures and into the vessel bottom head. 

Satisafactory compressor installations many times depend on how well the foundation or support structure was designed. An inadequate foundation design can result in equipment damage due to excessive vibration. The money saved by cutting comers on foundation design effort may be spent many times in costs associated with high maintenance and lost production. 

For describing structural loading functions needed for design analysis, the use of overdriven detonation data representing the net overpressure (run-up side less protected side overpressure) on the arrester element and supporting structure is preferable to data representing only the run-up side, side-on overpressure. However, the run-up side transient history of side-on overpressure for overdriven detonations should provide a conservative estimate for design purposes (see Chapter 6). 

Chemical evidence has been advanced for the formulation of p nitrosoindoles as either 115 or 116 (sec reference 119 and references therein), but ultraviolet spectral comparison with both methylated forms clearly indicated that 116 was favored. Infrared spectral data are also considered to support structure 116. °... 

The infrared spectra of 4-arylazopyrazol-5-ones have been- successively interpreted to support structures 62 (R = o-ClCeHi), either 62 (R = Me) or 63, 63/ and 64. The available ultraviolet spectral evidence favors structure 64. "... 

Determine total dollars per fC of finned surface including standard (or specified) support structure, ladders, etc. 

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