asme学习笔记.docx

-2007
PV-ELITE
Mating flange loads
The use of mating flange value for bolt design calculations will result in incorrect MAWP calculations. You probably don’t want to calculate MAWP based on the mating flange values, but rather based on the value developed by this flange at a given pressure.
Flange design
1For slip-on type flanges, calculate the small end of the hub equal to roughly the thickness required for the design pressure.
2For weld neck, slip-on, and reverse flange, calculate the large end of the hub as the small end of hub plus 1/16th(for small end thickness less than one inch) or 1/8th(for small end thickness greater than one inch). Then calculate the hub length equal to the small end thickness plus the minimum slop (3:1) for the hub. The effect of those choices is to design the small hub pared with standardized flanges. This has the additional effect of keeping the moment arms and diameters (of the bolt circle and flange OD) small, and keeping the flange light. finally, a selection of the small hub
keeps the amount of machining required for a flange to a minimum.
3 Select a preliminary number of bolts. This is a multiple of four based on the diameter of the flange. The algorithm chosen tends to select more and smaller bolts than would be found on standard flanges. This also has the effect of minimizing the flange outside diameter and the weight of the flange.
4 Select a bolt size that will give the required bolt area for this number of bolts.
5 Using this bolt size, calculate a final number of bolts based on:
The area required divided by the area available per-bolt or the maximum allowed spacing between bolts of the size.
6. using this number of bolts, calculate the bolt circle based on :
The OD of the hub plus the minimum ID spacing of the bolt or the OD of the gasket face plus the actual size of the bolt or the minimum spacing between the bolts or for reverse flange, the vessel OD plus the bolt ID spacing.
7. calculate the