COMPRESS Tips
Learn to use the COMPRESS shortcut keys. Examples include:
"F3" - to generate Code reports
"F4" - to edit a component
"F7" - to set mode options
"F8" - to set datum
"Delete" - to delete a component
"Ctrl"+"F3" - to perform FEA-Nozzles calculations
"Insert" - to insert a component
"F2" - for nozzle design
COMPRESS can perform dimensional conversions automatically.
For example, when you input 6'7" and press the "tab" key, COMPRESS converts your input to 79". Similarly, you can also enter data as a basic mathematical expression. For example, an input of 1/167" will be automatically converted to 0.0625" when you press the "tab" key.
Use the COMPRESS "Undo" ("Ctrl"+"Z") and "Redo" ("Ctrl"+"Y") features to add back components deleted or changed by mistake.
The COMPRESS web based Support Center makes it easy to quickly locate the answers you need. In addition to searching the COMPRESS knowledgebase, COMPRESS calculation verification documents, manuals and video tutorials can also be downloaded as required.
Click the "Report" button on the Toolbar (adjacent to the F3 button) to toggle between the design and report windows for the same file.
Every open COMPRESS file has two (or more) windows associated with it: the design window (graphic) and the report (calculation) window.
COMPRESS determines the rated MDMT of each carbon steel component using Figure UCS-66.2. The pressure used when determining the MDMT is the vessel MAWP. This provides a colder rated MDMT than using the component's MAWP.
Vessels may be supported by support lugs or ring girders. The same design dialog is used but the method of analysis is very different. Lugs generate local stresses in the shell analyzed using WRC-107. Ring girders are analyzed as structural rings subject to radial loads directed inward and outward.
Support skirts may be comprised of multiple segments. This is useful when the skirt is comprised of different materials. Skirts may be comprised of both tapered and cylindrical sections.
Allowable compressive stresses for support skirts are determined using UG-23(b).
Determining the MAWP of a head involves only one equation for circumferential stress and one equation for the straight flange.
The MAWP of a transition may be limited by membrane stress, by longitudinal stress or by the junction reinforcing area requirements.
The MAWP of a nozzle may be limited by any one of a number of criteria. COMPRESS determines the nozzle MAWP by iteratively performing the Code calculations. The pressure is increased incrementally until one of the limiting Code criteria is just met. The corresponding pressure is by definition the MAWP.
Applying external loads on flanges will result in a reduced pressure capacity for that flange. COMPRESS automatically reduces the pressure rating of ANSI/ASME flanges based on the "equivalent pressure" related to the external loads.
Specify Minimal Reports to shorten the Code reports generated by COMPRESS.
COMPRESS considers the effect of external loads on the nozzle neck. For brevity, this calculation is only reported if the stresses are excessive.
COMPRESS provides a database of all materials listed in Section II, Part D. Any of these may be added to the material lists in the component dialogs.
COMPRESS provides a database of all structural sections from the AISC Manual of Steel Construction. These include angles, wide flanges, WTs, channels, flat bars and pipes. Any of these may be added to the lists that appear for stiffener rings and support legs.
The WRC-107 does not consider rectangular attachments on spherical shells. Thus, COMPRESS does not support clips or support legs attached to heads. Another concern for legs attached to the bottom head is the stability of the vessel under possible head buckling; this analysis is outside the scope of COMPRESS.
The WRC-107 is limited to rectangular attachments where the longer side is no more than four (4) times the length of the shorter side. A longer side may be entered as an attachment dimension; however, the WRC-107 analysis will be based on the 4:1 profile limit, which is conservative
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