Vessel anchors, vertical

Figure 3.28 Shear Transfer Methodology for Vertical Vessel Anchors...

The quencher arm shoiild be anchored to prevent pipe whip. It should also extend to the length (for horizontal vessels) or the height (for vertical vessels) of the vessel to evenly distribute the vapors in the pool. 

As far as vertical slim vessels are concerned, the most common damages in case of seismic event are the failure at the foundation, due to the excessive stress, and the loss of contained fluids because of failure of connected flanges, due to excessive relative displacements. For example, during the Loma Prieta earthquake a refinery was seriously damaged, where the most important effect was on the anchor bolts of about 20 vertical vessels, on a total of 50 vessels. During the Valparaiso earthquake in a ventilation-stack with diameter 18" the anchor bolts were subjected to a similar damage, with the yielding of bolts. 

Procedure 4-16 Design of Anchor Bolts for Vertical Vessels... 

A skirt is die most frequently used and most satis-faaory means of suppon for vertical vessels. It is attached by continuous welding to the bottom head of the vessel and is furnished with a base ring, which is secured to a concrete foundation or structural frame by means of anchor bolts. In most cases, the skirt is straight, but on tali, small-diameter towers, the skin could be flared. Access openings are required in vessel skirts for inspection and, when possible, should be oriented toward the main access way. Eidiibit 10-18 shows a typical skin arrangement. 

Determine the amount of expansion in the north-south direction, The distance to consider is from the anchored side of the exdhanger to the centerline of the vertical vessel. Reference Exhibit 16-15 for the thermal growth table. 

Most vertical vessels are supported by skirts, as shown in Fig. 12. la. Skirts are economical because they generally transfer the loads fix>m the vessel by shear action. They also transfer the loads to the foundation through anchor bolts and bearing plates. 

Anchors for tall vertical vessels are frequently not required to resist shear, since the shear is resisted by friction created by the large compressive force attributable to overturning. See 3.6 for the evaluation of frictional resistance. However, there are cases where the anchor may be required to transfer the shear load, such as for shorter vertical vessels or those subject to seismic design. See 3.11 for seismic design of anchors. Following are two alternative methods for designing the anchors to resist shear ... 

Anchors need not be designed for shear if it can be shown that the factored shear loads are transmitted through frictional resistance developed between the bottom of the base plate and grout at the top of the concrete foundation. If there is moment on a base plate, the moment may produce a downward load that will develop frictional resistance even if the eolumn or vertical vessel is in uplift, and this downward load ean be eonsideied in calculating frictional resistance. Care should be taken to assure that the downward load that produces frictional resistance occurs simultaneously with the shear load. 

Historically, the foundation anchors for tall vertical vessels and stacks have tended to stretch beyond yield when subjected to strong ground motion, which probably prevented collapse of these vessels. Based on this experience, it is recommended that... 

DTs are vertical, cylindrical vessels with a multitude of horizontal trays. The extracted material enters at the top and is supported by the tray. The material is mixed above each tray, and it is conveyed downward from tray to tray, by agitating sweeps anchored to a central rotating shaft. The heat for increasing meal temperature and evaporating the solvent is supplied by steam, introduced directly and indirectly into the meal via the trays. Figure 10a illustrates a typical Schumacher DT. 

Vertical cylindrical vessels which are directly anchored to foundations and free along the height. This category includes the distillation columns and many other reactors. The distribution of the mass along the height is usually rather uniform and it may be considered as continuous, even though some internal discontinuities could be present. 

The prestressed concrete vessel has a cavity with a diameter of about 12 and a depth of about 38 m, containing some 3,300 m of water. The concrete vessel is a monolith with a cross-section of about 27 and a height of about 43 m. It is anchored to the foundation mat structure by means of prestressing tendons. The pressure retaining capability of the vessel is ensured by a large number of prestressing tendons - partly horizontal tendons run around the cavity, partly vertical tendons run from the top to the bottom, - and by reinforcement bars. 

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