Orifice flanges, closeness

The reason the orifice flanges are kept close to the orifice plate is that when the liquid velocity decreases, downstream of the orifice plate, the pressure of the liquid goes partly back up. Figure 6.8 illustrates this point. It is called pressure recovery. Whenever the velocity of a flowing fluid (vapor or liquid) decreases, its pressure goes partly back up. An extreme example of this is water hammer. The reason the pressure at the end of the pipe in Fig. 6.8 is lower than at the inlet to the pipe is due to frictional losses. 

The primary lid is made of forged carbon steel (TStE 355) and is bolted with 28 bolts to the cask body. The primary lid is sealed off with a metal and an elastomer gasket. In the primary lid, one penetration is located for performing the necessary leak-tightness tests. This orifice is closed with a small lid (flange) and a metal gasket. 

Orifice flanges need not be accessible from grade or a platform but should be positioned at a location and elevation that can be reached by a portable ladder. Care must be taken at horizontal banks of lines to allow for adequate space for side-oriented taps and, when required, close-coupled transmitters. liqjend-ing on service, orifice flanges can be mounted in the vertical and horizontal seaions of piping, as shown in Exhibit 14-21, or with specific upstream and downstream dimensional requirements, as shown in Exhibit 14-22. For less common flow instruments (e.g., Pitot tubes and Annubars), advice from the instrument engineer is necessary for location and dimensional requirements. 

The reason the orifice flanges are kept close to the orifice plate is that when the liquid velocity decreases downstream of the orifice plate, the pressure of the liquid goes partly back up. Figure 10.8... 

Corner taps. Static holes drilled one in the upstream and one in the downstream flange, with the openings as close as possible to the orifice plate. 

The orifices are to be closed by blind flanges or caps. For control valves, flushing inserts can be ordered and installed. Pumps can be protected by installing blanks on the suction and pressure side. There is the alternative to protect sensitive plant parts through the installation of so-called start-up strainers or flushing sieves. When using start-up strainers for pumps it has to be considered that this will reduce the NPSHA-value. Therefore, in the case of cavitation-prone pumps operation with start-up strainers should be maintained only for a short time. 

The container is charged with molten lead through the orifice t when the ram head is slightly advanced so as to close tightly the container bore. The press is set on its foundation so that its front end is inclined down so as to permit the complete escape of air from the container while it is being filled the inclination is 1 12. A chamber u which is easily accessible from the side of the press, is arranged in the container flange... 

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