huangyhg

hss design wall thickness
per the aisc specification for steel buildings section b3-12 the design wall thickness for hss = .93t where t = nominal wall thickness.
how does this apply if we know the actual wall thickness? we buy relatively small quantities of pipe and know the actual wall thickness as opposed to the nominal thickness. a common pipe for us is 36" dia x .464 which appears to be .93*.5". so can i design with properties of .464 without reducing by another 7%?
by reading the commentary, it appears that the intent of this section was to account for mills working consistently on the bottom end of the tolerances.
your thoughts are greatly appreciated and i'm happy to answer any questions.
the design thickness is taken to be 0.93 times the nominal thickness. you are already using the actual thickness, so no further reduction is required.
taro is right. use 0.464".
from the old 9th to the recent 13th edition aisc has reduced listed values for the properties for tube shapes to reflect the 0.93t. i believe the weight per foot numbers did not change.
i had to look for myself to make sure, but aisc also changed the design values for "pipe" along with hss shapes.
i don't know how the mechanical industry looks at pipe stress - i doubt they are using the reduced values, yet.
the piping codes have been using 0.875*nominal thickness for a long, long time.

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