pressure thickness design
pressure thickness design
(OP)
I have a wall in a pressure vessel (1000F and 50psia) that we are designig. it is 15"x30" and we are comparing a flat plate and a hemispherical shell for the wall.
I have been reference to the following equations for determining the thickness of each of the above...
flat plate: t=d(ZCP/SE)
half pipe: t=PR/(2SE-0.2P)
where d is the shorter dimension
D is the longer dimension
Z is noncircular correction =3.4-2.4d/D
C is the joint factor (0.7)
R is the radius (7.5)
E is the joint efficiency (0.33)
P is the design pressure (50)
and using allowable stress of A516-70(1000F) S=12,000
in calculating it out i get that the flat plate is about 44x as thick as the half pipe! is this reasonable? am I using the equations correctly? any advice?
Thank you
I have been reference to the following equations for determining the thickness of each of the above...
flat plate: t=d(ZCP/SE)
half pipe: t=PR/(2SE-0.2P)
where d is the shorter dimension
D is the longer dimension
Z is noncircular correction =3.4-2.4d/D
C is the joint factor (0.7)
R is the radius (7.5)
E is the joint efficiency (0.33)
P is the design pressure (50)
and using allowable stress of A516-70(1000F) S=12,000
in calculating it out i get that the flat plate is about 44x as thick as the half pipe! is this reasonable? am I using the equations correctly? any advice?
Thank you





RE: pressure thickness design
Think about it - are your balloons spherical/cylindrical, or flat plates? For a given geometry and internal pressure, the sphere/cylinder is the most efficient use of material.
RE: pressure thickness design
RE: pressure thickness design
i'm guessing you don't, 'cause you're asking.
well, it ain't !
i'm guessing your structure is a flat panel, without stiffeners. flat plates don't like pressure (as noted above). they will deflect and in-plane membrane tension (like "hoop stress" in a fuselage) will help the plate react the pressure. displacements may still be too large to be acceptable ... so break up the flat plate with stiffeners (angles/tees welded/fastened to the plate).
i'm guessing you don't have access to an FEM ... how about Roark ?
if this is the way you ant to go, we can help with equations/solutions. you can look this stuff up on-line as well.
RE: pressure thickness design
RE: pressure thickness design
RE: pressure thickness design
RE: pressure thickness design
Timishenko's "Theory of Plates and Shells"
Young's "Roark's Formulas for Stress and Strain"
RE: pressure thickness design
Kenneth J Hueston, PEng
Principal
Sturni-Hueston Engineering Inc
Edmonton, Alberta Canada