Line locations pipe racks

Multielevation piperacks are usually needed to handle all the required services for piping, electrical, utilities, and instmmentation. The two-level rack is one of the most common but three-level ones are also used. The utility lines are usually mn in the upper level and the process lines in the lower levels. The larger-diameter lines are located to the outside of the rack to be closest to the column supports. Access platforms are required at the battery limit to provide operators access to the block valves and blinds. If long mns of hot pipe are required, a portion of the pipe rack needs to be dedicated to an expansion loop. A horizontal space in the piperack is provided for a set of lines to be flat-turned into a set of expansion loops with the large pipes located on the outside. AH of the pipe turns are in the same horizontal plane, which is an exception to normal piping practice. A flat turn takes up and blocks space for other pipes. Flat turns are generally only made from the outside of the rack to minimize this blockage. 

Many ftictors must be considered when locating each line, valve, and instrument in a pipe rack. Exhibit 11-10... 

When locating lines in the rack, the plant layout designer should run the largest lines near the outside where possible to reduce the overall load on the supporting beams. Meter runs should be installed direaly next to die columns so diat access is available by portable ladder or mobile platform, as shown in Exhibit 11-11. Maer runs are located in the pipe rack only when absolutely necessary. 

Such equipment as drums and deaerators is often located above pipe rack columns. To avoid wasting valuable rack space with the large support columns, the inside face of the pipe rack column must line up with the inside face of the equipment support column, as shown in Exhibit 11-26. This approach also allows the feed-water outlet piping to run venically down to the pump before the expansion loq> is added. 

If the water users are located in a structure, the underground portion of the lines should terminate with bevel ends 12 in (300 mm) above grade. Cooling and hot water headers to the pumps are run under the pipe rack, between the rows of pumps, as Exhibit 13-24 shows. A self-draining hydrant valve is used if the installation is in a freezing climate this detail is displayed in item 8 of Exhibit 13-25. 

The location of the pipe in the rack is selected to minimize the congestion and eliminate line crossing. If a process line connects two nozzles which are elevated higher than the piperack, then the upper level of the rack is used. Similarly, if the nozzles are both below the piperack, then the lower level rack is used. Other cases in which one nozzle is below and the other above use the least congested part of the piperack. Lines with valves are more easily accessed from the upper level, but require an access platform. 

Figure 12 shows the plan and elevation views of a process unit piping (9). A dmm is supported off the piperack. Heat exchangers are located far enough back from the support columns so that they are accessible and their shell covers can be removed. Pumps are located underneath the piperack, but sufficient room is provided for maintenance equipment to access the motors and to remove the pump if necessary. The motor is always oriented away from the process equipment and located on that side of the piperack. Instmment valve drops are shown supported from the columns. The instmment trays themselves mn on the outside of the support columns. Flat turns are only made from the outside position of the piperack. Nozzle-to-nozzle pipe mns are made whenever possible. Larger lines are located on the outside of the piperack. Connections to nozzles above the rack are made from the top... 

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