pad-eye calculations and frame stress verification...simulation of lifting @ 2.5 swl using 4 lifting...

W-Industries, Inc.Subsea Control Project: 14035 - BLIND FAITH UPS PANEL11500 Charles Road Engineer: Haider KazzazHouston, TX 77041 Date: April 20, 2007

Revision: 0D, (ECN: 14035-11) Length from Bolt Hole Center to Padeye Edge ( R ) 2.5 inches

Height (H) 1.75 inchesPadeye Width (W) 5 inches

Padeye Thickness (t) 0.5 inchesHole Diameter (D) 1.125 inchesPadeye Radius (R) 2.5 inches

Shackle Pin Diameter (Dp) 1 inchessafe working load for the unit (SWL) 3158 lbs

Number of pad-eyes (n) 4 lbsLift Point SWL (LPSWL) = SWL / n 789.5 lbs

%Out of Plane (%OOP) 5 %Sling Angle (θ) 60 degrees from horizontal

Pad-Eye Design Load (Fr) = 3xSWL / (N-1) . Cos(90-θ) 3,647 lbsVertical Load (Fv) = Fr x Sin (θ) 3,158 lbs

Horizontal Load (Fh) = Fr x Cos (θ) 1,823 lbsWeld Metal tensile strength (Wt) 69,610 psi

Lug Material 316LLug Material Yield Stress (Fy) 24,650 psi

Case -1 : Pad-eye Shear Stress

Actual Shear Stress (fv)= 1,882 psi

Allowable Shear Stress (fv) =0.4xFy 9,860 psi

Shear stress case pass (safe) when the actual shear stress is lower than the allowable shear stress

Checking Shear stress is OK

Case-2 : Pad-eye Combined stress

Actual Combined Bending, Tension and Out of Plane Stress: = 4,326 psi

Allowable Combined Stress =0.6xFy 14,790 psi

Combined stress case pass (safe) when the actual combined stress is lower than the allowable combined stress

Checking Combined stress is OK

Case-3 : Pad-eye Bearing stress

Bearing Stress = 7,293 psi

Allowable Bearing Stress =0.9xFy 22,185 psi

Bearing stress case pass (safe) when the actual combined stress is lower than the allowable combined stress

Checking Bearing stress is OK

Case-4 : Tear - Out Shear Stress

Stress Concentration Factor (SCF) = 3

Tear Out Shear Stress = 5,646 psi

Allowable Tear Out Shear Stress =0.85xFy 20,953 psi

Tear Out Shear Stress pass (safe) when the actual stress is lower than the allowable Tear - Out Shear Stress

Checking Tear - Out Shear Stress is OK

Pad-Eye Calculations and Frame Stress Verification

=× p

r

DtF

Figure - 1

=

−××

22

DRt

Fr

=

×

××+

×+

×

×

6

%

6

22 tW

HFOOPWtF

Wt

HF rvh

=− tDtRFSCF

h

r

...2.

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Case-5 : Pad-eye FEA

Results

Criteria of checking the FEA results

The loading is safe when Von Mises Stress (Figure-3) is lower than the allowable stress:

14100 psi

Allowable Stress = 0.85 x Fy = 20,953 lbs

Checking Loading Stress OK

Material Steel : Structural ( SS 316L)

Young Modulus 2.751e+007psi

Poisson Ratio 0.27

Density 0.289lb_in3

Thermal Expansion 0.0000117

Yield Strength 24656.4psi

Applied Loads: > sling load (3647 lb)> Out of Plane-1 (5% of Sling Load-182 lbs)> Out of Plane-2 (5% of Sling Load-182 lbs)

Figure - 3

Figure - 2

( ) =+++−+−+−= ]6)()()([21 222222

. yzxzxyzyzxyxMisesV τττσσσσσσσ

AllowableMisesV σσ <.

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Pad-eye Weld Calculations:

Weld Modulus

Total Weld Length Wl: 11 inches

Weld Section Modulus 11 in2 (Treated as a line)

Combined Stress Calculation

Weld Bending 295 lb/in

Weld Shear 166 lb/in

Weld Tension 287 lb/in

Combined stress 605 lb/in

Allowable stress and force per in of leg Allowable force per in of leg = .707*.47*yield stress= 8190.9 (lb/in)/(1 in leg)

Allowable Weld Stress (0.47xWt) Weld Allowable 11,586 psi

Weld Fillet Calculation

= Minimum Fillet Weld Size (ω) = 0.0738 inch

Applied Fillet Weld Size Used (ωa)= 0.25 inch

Actual Effective Weld Throat Area (wa)= 1.94 in2

Transverse Load Capability= 22,525 lbs

Criteria of checking the weld lengthEach stress (Twisting, Bending, Shear, Tension and Combined) should be less than the allowable force per in of legCheckingWeld length and stresses are OK

Criteria of checking the Weld FilletThe actual applied weld fillet should be greater than the calculated minimum fillet size (w)CheckingApplied Fillet Weld size (Wa) OK

=×

=x

hb S

HFf

==LFf h

v

==LFf v

t

ω==legofinperforceallowable

fff actual

allowable

actual

=×+× tW 22

=+×=3

2WtWSx

( ) =++= 22vtbactual ffff

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Simulation of Diagonal Lifting @ 1.5 SWL

Results



7010 psi

Allowable Stress =0.85xFy= 20,953




Poisson Ratio 0.27

Density 0.289lb_in3



Testing @ 1.5 SWL = 1.5 x 3158 = 4737 lbs

Figure - 5

Figure - 4

( ) =+++−+−+−= ]6)()()([21 222222



Figure - 4

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Simulation of Lifting @ 2.5 SWL Using 4 Lifting Points

Results



16800 psi

Allowable Stress =0.85xFy= 20,953




Poisson Ratio 0.27

Density 0.289lb_in3



Testing @ 2.5 SWL = 2.5 x 3158 = 7900 lbs

Figure - 7

( ) =+++−+−+−= ]6)()()([21 222222



Figure - 6

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Summary and Conclusion

A) Pad-eye design verificationActual Allowable Fail if Actual Stress >= Allowable stress

Stress PSI Stress PSI Ok / Fail

1,882 9,860 OK

4,326 14,790 OK

7,293 22,185 OK

5,646 20,953 OK

14100 20952.5 OK

B) Pad-eye Weld length VerificationActual Allowable Fail if Actual Stress >= Allowable stress

Stress lb/in Stress (force per in of leg) lb/in Ok / Fail

Weld Bending 295 8190.9 OK

Weld Shear 166 8190.9 OK

Weld Tension 287 8190.9 OK

Combined stress 605 8190.9 OK

C) Pad-eye Weld Fillet Verification

Applied Minimum Calculated Fail if Applied fillet <= Minimum FilletFillet (in) Fillet (in) Ok / Fail

Weld Fillet Calculation 0.25 0.0738 OK

D) FEA for FrameActual Allowable Fail if Actual Stress >= Allowable stress

Stress lb/in Stress PSI Ok / Fail

Simulation of Diagonal Lifting @ 1.5 SWL 7010 20952.5 OK

Simulation of Lifting @ 2.5 SWL Using 4 Lifting Points 16800 20,953 OK

ConclusionThe pad-eye is designed using 1/2” SS 316L @ 3 SWL. The pad-eye shape and dimensions were determined using engineering analysis, geometry constrains as well as FMC guidelines G03.33.

All the above mentioned items for the pad-eye part and weldment show a safe operation under the 3 SWL applied load.

The simulation of diagonal lifting @ 1.5 SWL shows that the Von Mises Stress found to be lower than the allowable stress

The simulation of lifting @ 2.5 SWL shows that the Von Mises Stress found to be lower than the allowable stress

Case # and Description

Case-3 : Pad-eye Bearing stress

Case-4 : Tear - Out Shear Stress

Case-5 : Pad-eye FEA


Case-2 : Pad-eye Combined stress


Case -1 : Pad-eye Shear Stress

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pad-eye calculations and frame stress verification...simulation of lifting @ 2.5 swl using 4 lifting...

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