Davit Cal 2251B (Davit Arm Calculation)

V-2251 B Doc No JI-191-030020-DM05-013 - Rev B2 Page 97

DESIGN OF DAVIT In accordance with pressure vessel design manual by Dennis Moss Notation : P Axial Load A Cross-sectional area Z Section modulus r Radius of gyration tp Wall thickness of pipe davit a Outside radius of pipe L1 Length of davit L2 Height of pipe from support fa Axial Stress fb Bending stress Fa Allowable axial stress Fb Allowable bending stress αβK Stress coefficients R Radius of bent of davit M1 Bending moment in davit at top support M2 Maximum bending moment in curved davit I Moment of Inertia Fy Minimum specified yield stress fv Vertical force fh Horizontal force W1 Weight of davit

Size of davit pipe used - OD 88.9mm * 7.62mm thk Weight of blind flange - 293.00 kg Weight of nozzle N2 - 24.00 kg Weight of nozzle N5 - 5.8 kg Miscellaneous weight - 10 kg Hence Total weight of the blind flange is 332.8 kg ~

335 19.458 36.46 2.885 7.62 44.45 562 375 17.22

kg cm² cm³ cm mm mm mm mm kg/cm²

= = = = = = = = =

739 3.016 2.225 1.136 0.3 1.75 22.12 14.76 244.78

lbs in² in³ in in in in in lb/in²

=

12

in

=

3.8943

in4

13250 psi 21000 psi 305 mm

162.09 35000 335 335 16

335

cm4 psi kg kg kg

= 739 = 739 = 35

lbs lbs lbs

kg

Material Specification of davit pipe - SA-106 Gr B Yield strength of pipe = Fy = 35000 psi Allowable bending stress Fb = 0.6*Fy = 21000 psi Allowable axial stress Fa = 13250 psi (From sec VIII Div 1 Appendix-L, Ed 2007 allowable compressive stress for columns) Axial Stress fa = P = A

17.22 kg/cm2 =

244.78 lb/in²

Page 98 Bending moment in davit pipe at top support M1 M1 = fv*L1 + 0.5*W1*L1 + fh*L2 = 27641.42 in-lb

V-2251 B Doc No JI-191-030020-DM05-013 - Rev B2

Maximum bending moment incured at davit M2 M2 = M1 (L2 - R) L2 = 5168.72 in-lb Coefficients α = tp* R= a² β=

1.176

6 = 5+6*α²

K= 1-

0.45

9 10+12α²

Bending Stress at M1, fb = M1 Z

0.6617

12423.11 psi

M2, fb = M2 * a * 2 I (3K √ 3*β) = 2011.68 psi

Combined stress fa + fb =