Lifting Lug Calculation

www.engineersknowledge.com LIFTING LUG

* DESIGN DATA Wi =

- Total empty empty weight weight - Safety Factor - Number of Lifting Lug * SKETCH OF LIFTING LIFTING LUG : w2

z N

kg

= =

1.25 2

V

We

t2

α

d w1

P M

L2

R 

 N

w1

L1 w2

Dimension : Lug thickness

t1

mm

Lifting Lug materia

Lug pad thickness

t2

mm

Pad materia

 Angle of lifting

α

Lug length at bottom

L2

mm

Lug hole diameter 

d

mm

Lug outside radius

R

mm

Lug pad length

M L1

mm mm

Weld leg at lug to pad

N w1

mm mm

Weld leg at pad to shell

w2

mm

Impact factor 

Df 

Height of Lug hole Lug pad width

1.5

* DEFINITION OF ALLOWABLE STRESS - Lug Yield Strength σya - Lug allowable stress σa = 0.6* σya - Pad Yield Strength σyb - Pad allowable stress σap = 0.6* σy b - Allowable tension stress σt = smaller value of (1.5* σa) or (0.6*σya) - Allowable bending stress σb = smaller value of (1.5* σa) or (0.66*σy a) - Allowable shear stress σs = 0.4*σya - Allowable weld stress σw = 0.49* σt

=

kg/mm2

= =

kg/mm2 kg/mm2

=

kg/mm2

=

kg/mm2

=

kg/mm2

=

kg/mm2

=

kg/mm2

t1

www.engineersknowledge.com LIFTING LUG

* DYNAMIC EFFECT ON EQUIPMENT - Dynamic Load W = W i * z * Df 

=

kg

- Vertical load per lug V=W/N - Vertical load per lug W e = V / cos α

=

kg

=

kg

- Horizontal load per lug P = V * tan α

=

kg

=

kg/mm2

=

mm2

* STRESS AT LUG - Shear stress at top of lug due to We S1 = W e / A where : A = t1 * (2R - d) Criteria :

S1 <

s

OK or NOT OK

σ

- Tension stress at top of lug due to V S2 = V / (L2 * t1) Criteria :

S2 <

t

S3 <

S4 <

b

C1 <

a

SW2 <

SW3 <

=

w

kg/mm2 OK or NOT OK

σ

=

σw

kg/mm2 OK or NOT OK

=

w

kg/mm2 OK or NOT OK

σ

* APPLIED LOAD DURING LIFTING - Radial load Pr = V - Circumferential shear  Vc = W e

kg/mm2 OK or NOT OK

- Bending Stress in weld part at Lug to Pad SW3 = (6 * P * L1) / (2 * w1 * L2^2 ) Criteria :

=

σ

SW1 <

kg/mm2 OK or NOT OK

- Shear stress in weld part at Shell to Pad SW2 = W e / (2 * (M + N) * w2) Criteria :

=

s

σ

* STRESS AT WELD - Shear stress in weld part at Lug to Pad SW1 = W e / (2 * L2 * w1) Criteria :

kg/mm2 OK or NOT OK

- Combined stress at top of lug C1 = ((S1 + S4)^2 + S3^2)^0.5 Criteria :

=

σ

- Shear stress at top of lug due to P S4 = P / (L2 * t1) Criteria :

kg/mm2 OK or NOT OK

σ

- Bending stress at top of lug due to P S3 = (6 * P * L1) / (t1 * L2^2) Criteria :

=

=

kg

=

kg

- Longitudinal shear  Vl = P - Circumferential moment Mc = W e * L1

=

kg

=

kg.m

- Longitudinal moment Ml = P * L1

=

kg.m

- Torsion moment Mt

=

0

kg.m