Lifting Lug

in support lug calculation stresses in shell lug support attack angle is 0?

what is attack anglr concept this is reference to pressure vessel design?

****************************************************

Support Lugs
Support material: SA285 Gr.C
This support is attached to: SHELL
Distance from baseplate to datum: 1,600 mm
Local shell outer diameter, new: 1,119.6 mm
Local shell thickness, new: 11 mm
Local shell inner corrosion: 3 mm
Local shell outer corrosion: 0 mm
Lug allowable stress Sb =1,103.799 kgf/cm2
Top plate width Wp = 70 mm
Top plate thickness ta =12 mm
Base plate width b = 245.2 mm
Base plate thickness tb =16 mm
Base plate load bearing width Lb =100 mm
Shell to center of load bearing area d =195.2 mm
Gusset height h =343 mm
Gusset thickness tg =12 mm
Gusset separation Lg =200 mm
Lug length, circumferential directionL =250 mm
Lug attachment fillet weld size: 7 mm
Pad width, circumferential direction: 300 mm
Pad length, longitudinal direction: 430 mm
Pad thickness te =11 mm
Pad attachment fillet weld size: 8 mm
Radial/bending lug stiffness ratio: 2
Number of support lugs: 4
ITEM NO. 105-A-501A/B
86/98

Stresses in Shell at Lug Supports
Condition
Total
Weight
(kg)
Shear
V
(kgf)
Moment
M (kgfm)
Lug
orient
Lug Loading Stress in Shell
(kgf/cm2)
W
(kg)
Pr
(kgf)
VL
(kgf)
ML
(kgfm)
Vc
(kgf)
Mc
(kgfm)
Primary
Circ (PL)
Primary
Long
(PL)
Combined
PL+Pb+Q
Wind, operating,
corroded
Attack angle = 0°
4,095 410 304
0° 614 -137 413 80.57 0 0.00 1,149.518 577.36 1,202.67
90° 1,024 0 1,024 199.85 68 13.35 1,172.649 598.523 1,271.289
180° 1,024 137 1,225 239.18 0 0.00 1,168.993 601.476 1,273.75
270° 1,024 0 1,024 199.85 -68 -13.35 1,172.649 598.523 1,271.289
Wind, operating,
corroded
Attack angle = 45°
4,095 410 304
0° 614 -73 472 92.09 -73 -14.16 1,145.51 577.149 1,198.1
90° 614 -73 472 92.09 73 14.16 1,145.51 577.149 1,198.1
180° 1,024 73 1,166 227.66 73 14.16 1,173 601.616 1,278.32
270° 1,024 73 1,166 227.66 -73 -14.16 1,173 601.616 1,278.32
Wind, operating, new
Attack angle = 0° 4,364 410 305
0° 655 -137 453 88.38 0 0.00 829.059 417.482 864.283
90° 1,091 0 1,091 212.95 68 13.35 845.581 432.036 909.842
180° 1,091 137 1,293 252.34 0 0.00 843.823 433.653 911.388
270° 1,091 0 1,091 212.95 -68 -13.35 845.581 432.036 909.842
Wind, operating, new
Attack angle = 45° 4,364 410 305
0° 655 -73 512 99.91 -73 -14.16 826.739 417.201 861.4
90° 655 -73 512 99.91 73 14.16 826.739 417.201 861.4
180° 1,091 73 1,234 240.81 73 14.16 846.214 433.934 914.412
270° 1,091 73 1,234 240.81 -73 -14.16 846.214 433.934 914.412
Wind, empty, corroded
Attack angle = 0° 1,752 410 304
0° 263 -137 61 11.97 0 0.00 20.811 14.975 90.626
90° 438 0 438 85.52 68 13.35 -28.615 -19.545 82.329
180° 438 137 640 124.85 0 0.00 -58.636 -34.591 -150.035
270° 438 0 438 85.52 -68 -13.35 -28.615 -19.545 82.329
Wind, empty, corroded
Attack angle = 45° 1,752 410 304
0° 263 -73 120 23.49 -73 -14.16 16.803 18.35 91.891
90° 263 -73 120 23.49 73 14.16 16.803 18.35 91.891
180° 438 73 581 113.33 73 14.16 -46.895 -29.107 -125.006
270° 438 73 581 113.33 -73 -14.16 -46.895 -29.107 -125.006