A pipe rack is the main artery of a processing unit. It connects all equipment with lines that cannot run through adjacent areas. Because it is located in the middle of the most plants, the pipe rack must be erected first, before it becomes obstructed by rows of equipment. Pipe racks carry process, utility piping and also include instrument and electrical cable trays as well as equipment mounted over all of these. Fig. 1 shows a typical pipe rack.\n\n\n\nThis is a small presentation on Pipe Rack and Rack Piping. It will be very helpful for beginners in the piping industry. This article will cover the following points in brief:\n\n\n\nINTRODUCTIONPIPE RACKPipe Rack design criteriaShapesFuture SpaceWidth of Pipe RackClearancePipe Rack LoadingRACK PIPINGPositions of Lines (Process & Utilities)Hot Lines & Cold LinesBigger Size LinesPipe SpacingAnchor BayUnit Battery LimitExpansion LoopsPipe RouteTrays\n\n\n\nData Required for Pipe Rack Development\n\n\n\nThe primary data required for the detailed development of a pipe rack:-\n\n\n\nPlot PlanP&ID\u2019sClient SpecificationConstruction MaterialsFireproofing requirementsStatutory requirements\n\n\n\nFig. 1: Typical pipe rack\n\n\n\nPipe Rack Design Criteria\n\n\n\nShapes of Pipe Rack\n\n\n\nThere are various shapes of pipe rack like L\/T\/U\/H\/Z. These shapes shall be considered based on the area available.\n\n\n\nFuture Space Requirement in Pipe Rack\n\n\n\nThe total width of the pipe rack shall include 25% extra space for future expansion\/modification in the unit for rack-width up to 16 m and 10% for rack-width above 16 m. The future space %age is normally based on client requirements.\n\n\n\nWidth of Pipe rack\n\n\n\nThe width of the rack shall be 6 m, 8 m, or 10 m for single bay and 12 m, 16 m, or 20 m for double bay having 4 tiers maximum. The spacing between pipe rack portals shall be taken as 6m in general. However, it can be increased to 8m depending on the size of the pumps to be housed below the pipe rack.\n\n\n\nClearance criteria in Pipe rack\n\n\n\nFor units, clearance beneath pipe rack shall be 4 m minimum both in longitudinal and transverse directions.\n\n\n\nFor Offsite, clearance beneath pipe rack shall be 2.2 m minimum both in longitudinal and transverse directions.\n\n\n\nRoad clearance shall be 7 m for the main road and 5 m for secondary road.\n\n\n\nRack Width Selection Criteria \n\n\n\nRefer Fig. 2 for details\n\n\n\nFig. 2: Rack width selection criteria\n\n\n\nPipe Rack Loading\n\n\n\nPipe rack loads shall be given by stress group to Civil & structural discipline for pipe rack design.\n\n\n\nSustain Load (Dead Load): Weight of piping, valve and load insulationThermal Load: Load by thermal expansion of piping & Reaction force by the internal pressure of expansion bellowsDynamic LoadLoad by the vibration of piping & by wind and earthquakeSustained Load (Live Load): Liquid load for the hydrostatic pressure test\n\n\n\nGuidelines for Rack Piping\n\n\n\nPosition of Lines in a Pipe Rack: \n\n\n\nPredominantly process lines are to be kept at a lower tier and, utility & hot process lines on the upper tier.\n\n\n\nHot Lines & Cold Lines in a Pipe Rack: \n\n\n\nGenerally, hotlines & cold lines are to keep at different tiers or at different groups on a tier.\n\n\n\nPipe Spacing inside Pipe rack: \n\n\n\nMinimum spacing between adjacent lines shall be decided based on O.D. of bigger size flange (minimum rating 300# to be considered), O.D. of the smaller pipe, individual insulation thickness, and additional 25mm clearance. Even if the flange is not appearing the min. spacing shall be based on the above basis only. Actual line spacing, especially at \u2018L\u2019 bend and loop locations, shall take care of thermal expansion\/thermal contraction\/non-expansion of adjacent line. Non-expansion\/thermal contraction may stop the free expansion of the adjacent line at \u2018L\u2019 bend location.\n\n\n\nBigger Size Lines: \n\n\n\nLarge size lines (14\u201d and larger) shall be arranged close to the column in order to decrease the bending moment of the beam. Water lines more than 30\u201d shall not be routed over pipe rack, these shall be routed underground.\n\n\n\nAnchor Bay in a Pipe rack\n\n\n\nAnchors on the racks are to be provided on the anchor bay if the concept of anchor bay is adopted. Otherwise, anchor shall be distributed over two to three consecutive bays.\n\n\n\nAnchors shall be provided within the unit on all hotlines leaving the unit.\n\n\n\nPipe Route: \n\n\n\nRacks shall be designed to give the piping shortest possible run and to provide clear head rooms over main walkways, secondary walkways, and platforms.\n\n\n\nTrays: \n\n\n\nGenerally, the top tier is to be kept for Electrical cable trays (if not provided in the underground trench) and Instrument cable ducts\/trays. Cable tray laying to take care of necessary clearances for the fireproofing of structure.\n\n\n\nBattery Limit (ISBL): \n\n\n\nProcess lines crossing units (within units or from unit to the main pipe way) are normally provided with a block valve, spectacle blind, and drain valve. Block valves are to be grouped and locations of block valves in the vertical run of pipe are preferred. If the block valves have to be located in an overhead pipe-way, staircase access to a platform above the lines shall be provided.\n\n\n\nExpansion loops in a Pipe Rack\n\n\n\nRefer to Fig 3.\n\n\n\nFig. 3: Examples of Expansion Loops\n\n\n\nThe expansion loop is provided on the high-temperature lines. This information shall be given by the stress group. All the loops shall be located around one column only.Make lines into a group and install a large size piping and high-temperature piping to the edge of the pipe rack.When necessary to install an expansion loop on the condensate line, do it horizontally to prevent water hammering. But do as above if the horizontal loop is impossible.\n\n\n\nEven though the presentation is not a detailed one still it will be useful for the beginners.