pressure vessel stiffener rings

huangyhg

pressure vessel stiffener rings
i'm a pump engineer so i need some help. i've been asked to determine if stiffener rings are required on some small (48" dia) vessels. they are normally operating in the 50 psig range, but can be subjected to as much as 15 in hg vacuum. i found some helpful information in the asme career development series "overview of pressure vessel design" but that article is missing the figures i need to determine the proper fudge factors. does anyone know where i can get all the data i need (for free of course; i know there are a lot of software programs out there but its not likely i will need to make this type of calc very often). thanks
as a first check you could see what external pressure would collapse a 48" diameter pipe.  if i'm not mistaken, that formula is in asme b31.3  let me know if its not there, i've got it somewhere.
   going the big inch!
thanks biginch. i checked out b31.3 and in para 304.1.3 it does address this subject but unfortunately it only refers to ug-28 and ug-30, which i guess is part of the pressure vessel code. i think that is what i need, i just don't have it. and i don't think my boss is willing to fork over hundreds of bucks to purchase it so i can make one calc.
check this out
cheap #@%q@!#$@!
see if you can locate "useful information for design of tanks" (title may vary slightly), published by aisi/spfa.  also, roark's formulas for stress and strain has equations for external pressure (be sure and add in safety factor if using roark, he just gives critical buckling pressure).  neither approach is exactly the same as asme, but if it doesn't actually need to meet asme code, they will work.  if they do need to meet asme code, then there's no real substitute for having it.
thanks jstephen. i looked in roarks but that's probably not going to do it for me. it looks like i just flat need the asme pressure vessel code because i need to calculate minimum wall thickness required for a slight external pressure (this is a thin walled vessel, 7-12 gauge)
the pressure vessel handbook by eugene f. megyesy should give you what you need to check for the external pressure and fit your budget