Page 252 - Pressure Vessel Design Manual

230 Pressure Vessel Design Manual

Stiffener Design
Unstiffened Baffle Check
Divide baffle into panels to limit deflection to the lesser of
Find load, p.
td2 or b/360. Deflection is calculated based on the appro-
62.4aSg priate Cases 1 through 3.
p =-
144
Find ba& thickness, tb. 1 b t
1 1

Find bafle defEection, 6.

a
Limit deflection to the smaller of td2 or b/360. If dellation
is excessive then:

a. Increase the baffle thickness.
b. Add stiffeners.
c. Go to curved baffle design. b‘ 1

If stiffeners are added, the first step is to find the maximum lk!
“a” and “b” dimensions that will meet the allowable deflec-
tion for a given panel size. This will establish the stiffener Figure 4-15. Example of stiffener layout.
spacing for both horizontal and vertical stiffeners. The ulti-
mate design is a balance between baffle thickness, stiffener
spacing, and stiffener size. Check bafle for panel size a’ x b’.
Check stiffener for length a or b.
-
Thermal Check of Baffle
Do’s and Don’ts for attaching stiffeners
Vessel radial expansion due to pressure.

0.85PRm
A1 =
tE
Vessel radial expansion due to temperature.

0 Thermal expansion of baffle.

A3 = 0.5b~ AT
DO DON’T
Differential expansion.

Bene$ts: Provides added stiffness and no corrosion trap.