Q. Explain about Unit pipe racks?

Unit pipe racks are the main arteries carrying the pipes and cables into the units, and as such should be centrally located. They are usually elevated, and are of sufficient height to allow vehicle access beneath. The width of rack will be determined by the number of lines and cable trays with an allowance for future requirements.

Piping should enter/leave from above or below the rack level. Piping should not flat turn on or off the rack closing out space for installation of future lines. Lines requiring expansion loops should be located close to pipe rack columns and should be grouped together to enable use of common supports. Space between levels must be sufficient to allow the largest lines to leave or enter the rack.

Electrical and instrument cable trays are normally run in or off the side of the pipe racks. The Piping Designer shall liaise with these disciplines to allocate these areas. Cable trays systems shall be kept away from hot lines. When there are large numbers of cable trays, they should be installed at the highest levels of the rack and process pipes should not be crossing or running above them.