Page 186 - Pressure Vessel Design Manual

164 Pressure Vessel Design Manual
PeD 48Mx wh
-
Longitudinal Stresses a,, = compression side = (-) - - -
-
4t nD2t rcDt
~ ~~ ~~ ~
In the following equations, D is in inches. The term
“48Mx” is used for ft-lb or ft-kips. If in.-lb or in.-kips are e Allowable longitudinal stresses.
used, then the term “4M: should be substituted where
‘‘48M,” is used. The allowable stresses SlEl or B may be tension : SlEl =
substituted in the equations for t to determine or veri5
thickness at any elevation. Compare the stresses or thick- compression:
nesses required at each elevation against the thickness
required for circumferential stress due to internal pressure
to determine which one will govern. If there is no external A=- 0.125t
pressure condition, assume the maximum compression will Ro
occur when the vessel is not pressurized and the term PeDMt
will drop out. B=from applicable material chart of ASME Code,
Section 11, Part D, Subpart 3.
PiD 48Mx Wh Note: Joint efficiency for longitudinal seams in compres-
+
O~ = tension side = - -
-
4t nD2t rcDt sion is 1.0.
~
Tension Compression