Instrument locations pipe racks

Main banks of aboveground instrument runs in cable trays (such as those coming from the control room and supported on process unit pipe racks) that are located inside process unit battery limits should be considered for fireproofing by one of the following passive methods ... 

Multielevation piperacks are usually needed to handle all the required services for piping, electrical, utilities, and instrumentation. The two-level rack is one of the most common but three-level ones are also used. The utility lines are usually run 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. All 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... 

Pipe racks and elearical and instrument cable trays should be located in the same general area, preferably down the middle of the structure. 

Another responsibility of the plant layout designer is to establish the location of the instrument cable trays and analyzer houses. Both items are coordinated with the instrument engineer during the early phase of the job. The main instrument cable runs are located either in elevated trays, generally in the pipe rack, or below ground in cable trenches. These requirements are dis-cu.ssed in Chapters 11 (Pipe Racks) and 13 (Underground Piping). 

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. Instrument valve drops are shown supported from the columns. The instrument 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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