Welding skirt supports

Design and analysis of welded pressure vessel skirt supports. 

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 sldrt, the better it is able to adjust to temperature variations. A hot box design is... 

Components Parts that make up a piece of equipment or equipment itan. For example, a pressure boundary may consist of components (pipe, elbows, heat exchanger tubes, heads, shells, nozzles, skirts, supports, etc.) that are bolted or welded and assembled to make up equipment items [10]. 

Integral pipe attachments are welded directly to the pipe and are usually of special design. They are used in high temperature services, with moderate or severe loads, and in conjunction with supports, braces, and restraints where rigidity with the pipe shell is desired. Integral attachments may be grouped into five types ears, lugs, shoes, cylindrical tmnnions, and skirts (see Fig. 8). 

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. 

If there is no skirt, weld nuts to the underside of the head 16" C-C to support the insulation. 

Welded silos are fabricated in both fidly skirted and structural leg types. In the fully skirted silo, the tank side wall extends down to the foundation and provides the support for the structure. This enclosed area is extremely useful for locating items such as railcar unloader pumps, dehumidifiers and control panels, car unloading accessories, and flex hose. 

Sufficient space is provided within the stay cylinder to permit inspection of the welds. A 12 in. diameter access opening in the steam generator support skirt is provided. The insulation in this area is removable to the extent of the full size of the access opening. 

The pressurizer is supported by a cylindrical skirt welded to the pressurizer and bolted to the support structure. The skirt is designed to withstand deadweight and normal operating loads as well as the loads due to earthquakes, safety valve actuation, and Branch Line Pipe Breaks. Four keys welded to the upper shell provide additional restraint for earthquake, safety valve actuation, and Branch Line Pipe Break conditions. 

Rolled-anole Beahimg Plate. If the vertical vessel is not very high and a skirt is used to support the vessel rather than le, lugs, or columns, a simple design may suffice for the bearing plate. If the calculated thickness of the bearing plate is in. or less, a st l angle rolled to lit the outside of the skirt may he lap welded as shown in Fig. 10.3. 

In summary, all portions of the reactor vessel wall that are covered by water would be adequately protected against failure by melting or creep rupture. For the cases with no venting or partial venting of the support skirt, the creep rupture failure is predicted to occur in the portion of the vessel wall adjacent to the trapped gas pocket beneath the skirt. Partial venting would reduce the size of the gas pocket and delay the predicted time of failure, but the failure mechanism would still be creep rupture beneath the skirt attachment weld. With complete venting, however, there would be no gas pocket and this failure mechanism would be eliminated. 

Reactor Support Skirt welded to Vessel Shell... 

As already mentioned, Phenix was restarted in June 2003. The reactor was shut down in November 1998 for plant inspection, normal maintenance, and renovation works in view of its lifetime extension. The renovation works comprised buildings seismic reinforcement, sodium fires protection measures, installation of new emergency cooling circuits, and steam generator (SG) repair after the detection of a significant crack on one SG module. Inspection work comprised the ultra-sonic inspection of the welds of the core support conical skirt, and the visual inspection of the hanging structures of the vessel, and of the upper internal structures of the reactor block (above-core structures and subassembly heads). 

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