Wind Load
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Wind Load (W): Transverse wind load on structural members, piping, electrical trays,equipment, platforms, and ladders should be determined in accordance with project approved design code. Longitudinal wind should typically be applied to structural framing, cable tray vertical drop (if any), large dia pipes vertical drop (if any) and equipment only. The effects of longitudinal wind on piping and trays running parallel to the wind direction should be neglected. Earthquake Loads (E): Earthquake loads in the vertical, transverse, and longitudinal directions should bedetermined in accordance with the project design criteria. Vertical, transverse, and longitudinal seismic forces generated by the pipes, raceways, supported equipment, and the piperack structure should be considered and should be based on their operating weights. Pipes must be evaluated for seismic loads under both full and empty conditions and then combined with the corresponding gravity loads. Friction Loading (Tf): Friction forces caused by hot lines sliding across the pipe support during startup and shutdown are assumed to be partially resisted through friction by nearby cold lines. Therefore, in order to provide for a nominal unbalance of friction forces acting on a pipe support, a resultant longitudinal friction force equal to 7.5% of the total pipe weight or 30% of any one or more lines known to act simultaneously in the same direction, whichever is larger, is assumed for piperack design. Friction between piping and supporting steel should not be relied upon to resist wind or seismic loads. Anchor and Guide Loads (Ta): Piperacks should be checked for anchor and guide loads as determined by the Pipe Stress Group. It may be necessary to use horizontal bracing if large anchor forces are encountered. For conventional pipe rack systems, it is normally preferred to either have the anchors staggered along the piperack so that each support has only one or two anchors, or to anchor most pipes on one braced support. For initial design, when anchor and guide loads are not known, use a longitudinal anchor force of 5.0 kN acting at midspan of each bent transverse beam (refer
project design criteria). Guide loads are usually small and may be ignored until they are defined by the Pipe Stress Engineer. For non-continuous pipe rack systems, piping may be transversely guided or anchored at both cantilever frames and anchor bays. Longitudinal anchors may be located only at anchor bays. Please note that, all friction forces and anchor forces with less magnitude, (say ~ 5.0 kN), applied to the top flange of the beam, may be considered as resisted by the total beam section. When anchor loads have large magnitude and are applied to the top flange of the beam, the effect of torsion must be addressed.If the beam section is inadequate to take care of this torsional force, alternatives to be considered, such as provide horizontal bracings at the load locations.
project design criteria). Guide loads are usually small and may be ignored until they are defined by the Pipe Stress Engineer. For non-continuous pipe rack systems, piping may be transversely guided or anchored at both cantilever frames and anchor bays. Longitudinal anchors may be located only at anchor bays. Please note that, all friction forces and anchor forces with less magnitude, (say ~ 5.0 kN), applied to the top flange of the beam, may be considered as resisted by the total beam section. When anchor loads have large magnitude and are applied to the top flange of the beam, the effect of torsion must be addressed.If the beam section is inadequate to take care of this torsional force, alternatives to be considered, such as provide horizontal bracings at the load locations.
