Support Planning:- Types of support:Sleeper type: Durable, economical and easy to install, the precast concrete pipeline sleepers / supports are the answer to problems associated with metal, wood and cast-in-place concrete pipe sleepers. With the precast concrete pipeline sleeper there is no more corrosion or decay problems. Manufactured of high-strength steel reinforced concrete, the pipeline sleepers are resistant to salt and corrosive environments. With the precast pipeline sleepers, the product is delivered to the jobsite and can be set immediately when required, versus the cast-in-place sleepers which require costly onsite construction, supervision, weather delays and the task of getting ready-mix concrete to the most remote project sites. Onshore piping laid on sleepers at grade shall have minimum clearance of 400mm between bottom of pipe and finished grade. Rack type / Multi Level Lines: Whenever possible the Pipe rack shall be single level. On single level pipe racks, process piping shall be placed outsides with utility and service piping on the middle.
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Where multilevel racks are required, generally process lines shall be placed on the lower rack levels, and utility and service piping shall be placed on the upper rack level. 1· If both ends of a process line are lower than the lower level, the line should be run in the lower level. 2· Process lines that connect two nozzles elevated higher than the top level should be located in the top level. 3· Process lines having one end lower than the lower level can run in either the lower or upper level. Specific elevations shall be established and maintained for lines running the north / south direction, and different elevations for lines running east / west. North / south and east / west pipe racks shall intersect midway between deck levels. At every change of direction the piping should change elevation, but care should be taken to minimize pockets. Electrical and Instrument Cable Trays: These will normally be run in or off the side of the pipe racks.
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Piping Designers shall liaise with these disciplines to allocate these areas. Cable trays systems shall be kept away from hot lines. Continuous Pipe racks (conventional pipe rack) system: This is essentially a system where multiple 2-dimensional (2D) frame assemblies (commonly called bents), comprised of two or more columns with transverse beams, are tied together in the longitudinal direction utilizing beam struts (for support of transverse pipe and raceway elements and for longitudinal stability of the system) and vertical bracing to form a 3D space frame arrangement. Pipe racks supporting equipment such as air-cooled heat exchangers must utilize the continuous system approach. Data collection for pipe rack design: Due to the fast track nature associated with most of the projects, often the final piping, raceway, and equipment information is not available at initiation of the pipe rack design. Therefore, as a Civil/Structural Engineer, you should coordinate with the Piping group, Electrical, Control Systems, and Mechanical groups to obtain as much preliminary information as possible.
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When received, all design information should be documented for future reference and verification. In the initial design, the Engineer should use judgment when applying or allowing for loads that are not known, justifying them in the design basis under Design Philosophy (a part of your calculation). The following should be reviewed for design information:- Plot plans and equipment location plans. 3D model showing piping layout, cable tray layout, Pipe rack bent spacing and elevation of support levels in the transverse direction, Elevation of longitudinal beam struts and locations of vertical bracing. Vendor prints of equipment located on the rack, e.g., air coolers and exchangers. The vendor prints should include the equipment layout, mounting locations and details, access and maintenance requirements, and the magnitude and direction of loads being transmitted to the pipe rack. Electrical and control systems drawings showing the routing and location of electrical and instrumentation raceways and/or supports.
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Underground drawings that show the locations of buried pipes, concrete structures and foundations, duct banks, etc. Pipe rack construction material (Steel, Cast-in-situ concrete, Pre-cast concrete) shall be as per project design criteria. Type of Yard Piping: Process Piping, Drain Oil, Off-Gas Piping, Utility Piping and Others. Arrangement:- Piping arrangement shall be planned by grouping process and utility respectively. Small diameter piping shall be arranged in one area to allow easier support. Electrical and instrumentation ducts shall be arranged at the end of supports to allow easier check and maintenance. When horizontal loop is required in gravity flow piping such as flare, condensate lines, etc., such piping shall be arranged at the end of supports. Others:Road Crossing: In general, equipment layout shall be prepared considering straight pipe rack, however other shapes like L/T/U/H/Z etc can also be considered based on area available. The total width of pipe rack shall include 30% extra space or 1.5m (min) for future modifications in unit at later stage at all levels/tiers.
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