User load combinations
Once an analysis has been run, use Tools/Display combinations to see all code and non-code combinations. AutoPIPE automatically combines the loads required to calculate piping code stresses. The "Other" category contains loads, which need to be combined by the user in order to analyze piping loads on equipment, piping loads on supports, and deflections under various applied loading conditions.
In order to evaluate cold (ambient) load and operating loads on supports and equipment, users may combine individual loads by using Tools/User-defined Combinations/Non-code. For the combination name, choose something meaningful such as GR+T1, GR+T1+W1, etc. Typically, combinations for support and equipment loads are made using the Sum or Absolute Sum combination methods, although users may also use the SRSS combination or Resultant maximum methods to combine loads. On the same screen, select the loads to be combined to make up your operating loads (see Figure below).
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After defining all your operating load combinations (GR+T1, GR+T1+W1, GR+T1+W2, etc.), it may be a good idea to create 2 more combinations for your MIN and MAX to more easily review support loads. Typically, engineers will use the MIN and MAX for their GR and all operating load combinations, ignoring the individual loads for Tl, Wl, W2, El, E2, etc. The MIN and MAX sort through all the selected loads and load combinations, and produce Minimum and Maximum results. The MIN and MAX results for support loads and deflections are a great tool for creating summary reports for the civil/structural engineer responsible for piping support design, saving significant man-hours in the review of worst case loads on supports and equipment.
For reporting purposes, users can minimize output by selecting Tools/Non-code Combinations /Select and de-selecting individual loads or combinations which do not need to be reported. After saving these combinations, the model.cmb file can be copied and renamed to another job, eliminating the need to create user combinations each time.
Please note that users can input a "-1" in the load factor field to analyze wind and seismic loads in the negative direction, e.g. GR+T1-WI, GR+T1-W2. This "-1" feature can be used if gaps or friction do not significantly affect piping loads at a particular support point or equipment connection. This negative direction can be included as part of your user load combinations, enabling users to evaluate results using operating load combinations with wind and seismic analyzed in both the negative and positive directions. AutoPIPE does consider gaps and friction only for the load directions chosen for the original analysis.
Rotating equipment analysis
AutoPIPE will automatically take forces and moments from all selected loads and user combinations, and perform a rotating equipment analysis per selected rotating equipment code without having to manually enter loads from each operating condition. After defining operating load combinations as described above, go under Tools/Rotating Equipment. After inputting the equipment ID, select the rotating equipment code. Pump is API 610, compressor is API 617, Turbine is NEMA SM23. AutoPIPE also provides a User defined rotating equipment element in order to analyze equipment using vendor supplied allowable loads for up to four different terminal anchor points.
Depending on the rotating equipment code chosen, AutoPIPE will then ask the user to input the anchor points for suction, discharge, and other external connections as well as shaft axis. The API 610 analysis will require additional input for location of connection on the pump itself (side, top, or end), orientation, Table 2 factor, and center point offsets.
Once this basic information has been entered, AutoPIPE will automatically take the loads from all selected operating loads and user load combinations, and perform the rotating equipment analysis for each of these loading conditions.