Chance Technical Design Manual

EQUATION 8-60

EQUATION 8-68

W p = [D s x p x (42.0 2 - 40.124 2 )] / (4 x 144) = [490.0 x p x (1764.0 - 1609.935)] / (576) = 411.74 plf

F b = M max /S

where M max = Maximum moment at mid-span between pipeline anchor sets = (W n x L b 2 )/8 L b = [(8 x S x F b )/W n ] 1/2 = [(8 x 0.7032 x 8255.6 x 144)/453.0] 1/2 = 121.5 ft Allowable Span Length (L d ) Based on Mid-Span Deflection • Mid-span vertical displacement (Y) at center of span: EQUATION 8-69 Y = L d /360 L d /360 = (5 x W n x L d 4 ) / (384 x E x I) L d = [(384 x E x I) / (360 x 5 x W n )] 1/3 L d = [(384 x 29,000,000 x 25525.8/144) / (360 x 5 x 453.0)] 1/3 L d = 134.2 ft Y = (134.2/360) x 12 = 4.5 in ALLOWABLE SPAN LENGTH (L P ) BASED ON THE MECHANICAL STRENGTH OF PIPELINE BRACKET • Rated ultimate mechanical strength (UC p ) of pipeline bracket = 80,000 lb • Rated mechanical working capacity (WC p ) of pipeline bracket (using FS m of 2.0): EQUATION 8-70 WC p = UC p /FS m

• Moment of inertia (I) = 25515.8 in 4 • Section modulus (S) = 0.7032 ft 3 Properties of coating: • Weight per linear foot (W c ):

EQUATION 8-61

W c = [D c x p x (42.032 2 - 42.0 2 )] / (4 x 144) = [70.0 x p x (42.032 2 - 42.0 2 )] / (4 x 144) = 1.03 plf

Buoyancy: • Gross buoyancy (W g ):

EQUATION 8-62

2 /12 2 )] / 4 = [90.0 x p x (42.032 2 /12 2 / 4 = 865.8 plf

W g = [D b x p x (42.032

DESIGN EXAMPLES

• Net buoyancy (W n ):

EQUATION 8-63

W n = W g - W p - W c

= 865.8 - 411.74 - 1.03 = 453.03 plf (use 453.0 plf) Allowable Span Length (L b ) Based on Bending Stress • Maximum design pressure (P):

EQUATION 8-64

= 80,000/2 = 40,000 lb

P = [(2 x F y x T w )/OD] x F x E x T = [(2 x 65,000 x 0.938)/42.0] x 0.5 x 1.0 x 1.0 = 1451.7 psi (use given P d of 1440.0 psi)

EQUATION 8-71

WC p = (W n x L p /2) x 2 L p = WC p /W n = 40,000/453.0 = 88.3 ft

• Hoop stress (F h ):

EQUATION 8-65

F h = (P d x OD)/(2 x T w ) = (1440.0 x 42.0)/(2 x 0.938) = 32,238.8 psi

ALLOWABLE SPAN LENGTH (L a ) BASED ON THE UPLIFT CAPACITY OF ANCHORS IN SOIL (BORING B-1) • Ultimate uplift capacity (UC a ) ranges from 45,900 to 41,700 lb with overall anchor depths below ground line of 51’-0 to 60’-0. See Figure 8-25. Use UC a = 40,000 lb. • Working uplift capacity (WC a ) (using FS s of 2.0): EQUATION 8-72 WC a = UC a /FS s

• Longitudinal stress (F l ):

EQUATION 8-66

F l = (0.25 x P d x OD)/T w = (0.25 x 1440.0 x 42.0)/0.938 = 16,119.4 psi Allowable longitudinal bending stress (F b ):

EQUATION 8-67

= 40,000/2 = 20,000 lb

F b + F l = 0.75 x (F x E x T) x F y

F b = [0.75 x (0.5 x 1.0 x 1.0) x 65,000] - 16,119.4 = 8,255.6 psi

• There are two anchors located at each anchor support lo cation along the pipeline, therefore, the total working up lift capacity (WC s ) per anchor set = WC a x 2 anchors = 20,000 x 2 = 40,000 lb.

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