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Section 5
5-87
ASME Boiler and Pressure Vessel Code, Section III, NB-
3687.2, 1971, for Class I components is used to calculate the
flexibility reduction factor.
Set p = 0 or omit for this flexibility increase calculation to occur
with internal pressure equal to zero.
Set p > 0 to specify internal pressure to use in this flexibility
calculation. Pressure reduces the flexibility increase.
Set p = -9999 to ignore this additional flexibility calculation and
use only beam theory.
Set p = flexibility reduction factor (-FLEXF below); which must
be a negative number less than –1.0 .
___________________________________________________
0) ASME PIPE ELBOW FLEXIBILITY FACTORS
THEORY [ASME SECTION NB-3687.2]
This Section only applies if
(Bend Radius/Mean Radius) ≥ 1.70
or
if (Arclength) > (2 * Mean Radius)
FLEXF = (Flexibility Factor) =
165 1
1
2
.*( )
*( )
*
(Pr )( )( .)
Mean Radius
t Bend Radius ess Mean Radius FACT+
where
FACT
MR t BR MR
Et
.
*( / ) *( / )
//
=
6
43 13
MR = Mean Radius of elbow wall
BR = Bend Radius
Press = Internal Pressure
t = elbow wall thickness
E = Modulus of Elasticity
If the Flexibility Factor computed is less than 1.0, then STAAD
will use 1.0 . The Flexibility Factor directly multiplies or
contributes to most non-shear terms in the elbow flexibility matrix.