Operator access 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. 

Review of surrounding plants/facilities Existing pipe racks Maintenance and operations access Sewers and storm water drainage Existing fire and radiation circles Hazardous chemical releases from upwind locations Existing electrical area classification Close access to substations... 

Shut-off valves at utility headers are located inside the rack area in the horizontal position, directly above the header if room permits. Operating valves must be accessible from platforms or by chain operators. The location of the valve must also permit the chain to fall free of obstructions that would hamper operation. An additional 20% of space must be allowed for future pipe rack growth. An alternative approach to such expansion is shown in Exhibit 11-13. 

Provisions should be made for clearances between piping and vessels, piping in pipe racks, pipe flanges, and other equipment, expansion loops, headroom above access routes or access platforms, accessibility for suitable support points, valve orientation, operation and accessibility, and clearance to permit removal of in-line equipment with minimal dismantling of equipment. 

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