Fluid flow through a vertical to horizontal 90 degrees elbow bend III
Thrust Block Design (Horizontal Elbow)
30
THRUST BLOCKS FOR HORIZONTAL ELBOW ( Ø 900 mm, 90 deg ) Horizontal Thrust TABLE 1 DIMENSIONS IN mm FOR CONCRETE BLOCKS FOR 90 DEGREES BENDS - HORIZONTAL THRUST L A B C D E F 900 1779 3500 3300 5349 4000 1496 400 96.802 Design Parameters = 900 mm = 90 deg = 0.6362 = 18 = 24 = 10 Coefficient of frict = 0.40 = 0.150 m = 0.000 m At Working Pressure = 6 bars = 600 FGL = + 9.000 = 1.50 IL = + 6.400 = 1.50 GWT = + 4.400 = 1.20 At Hydrotest Pressure = 9 bars = 900 = 1.13 = 1.13 = 1.20 Soil Bearing Capacity (SBC) = 100 kPa PIPE DIAMETER (mm) CONC. VOL. (m 3 ) Pipe Diameter ( Angle of the be Area of Pipe (A m 2 Unit weight of soil kN/m 3 Unit weight of concr kN/m 3 Unit weight of water kN/m 3 Height of soil above thrust block Submerged height of thrust block ( Working Pressure ( kN/m 2 Factor of Safety against Overtu Factor of Safety against Slidin Factor of Safety against Buoyan Working Pressure ( kN/m 2 Factor of Safety against Overtu Factor of Safety against Slidin Factor of Safety against Buoyan Figure 1: Plan and Section for horizontal thrust block
description
Thrust blocks for horizontal elbows designed for 90, 60, 45, 30 22.5, and 11.25 degrees angle of bend.
Transcript of Thrust Block Design (Horizontal Elbow)
THRUST BLOCKS FOR HORIZONTAL ELBOW ( Ø 900 mm, 90 deg )Horizontal Thrust
TABLE 1 DIMENSIONS IN mm FOR CONCRETE BLOCKSFOR 90 DEGREES BENDS - HORIZONTAL THRUST
L A B C D E F
900 1779 3500 3300 5349 4000 1496 400 96.802
Design Parameters
= 900 mm= 90 deg= 0.6362
= 18
= 24
= 10Coefficient of friction (μ) = 0.40
= 0.150 m
= 0.000 m
At Working Pressure
= 6 bars = 600 FGL = + 9.000
= 1.50 IL = + 6.400
= 1.50 GWT = + 4.400
= 1.20
At Hydrotest Pressure
= 9 bars = 900
= 1.13
= 1.13
= 1.20
Soil Bearing Capacity (SBC) = 100 kPa
PIPE DIAMETER
(mm)CONC.
VOL. (m3)
Pipe Diameter (DP)Angle of the bend (q)
Area of Pipe (AP) m2
Unit weight of soil (gS) kN/m3
Unit weight of concrete (gC) kN/m3
Unit weight of water (w) kN/m3
Height of soil above thrust block (h1)
Submerged height of thrust block (h2)
Working Pressure (PW) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Working Pressure (PH) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Figure 1: Plan and Section for horizontal thrust block
G10
Robert.tan: Elbow Data given from FRP Table
Check on Soil Bearing Pressure
Thrust Block Plan Area = 24.767 Volume of soil = 3.715= 2323.260 kN (neglecting buoyancy) Wt of soil = 66.870 kN (on top of thrust block)
ΣV = Wt. of conc + Wt. of soil= 2390.130 kN
Static vertical pressure =ΣV
Plan Area96.507 kPa < SBC, Ok
Thrust Block Stability Check
1. At Working Pressure - 6 bar
== 539.810 kN
a. Check against OverturningTaking moments about O
x =A*(C+2B)
= 2.38 m3(B+C)y = D / 2 = 2.000 m
== 5522.70 kN.m
== 0.000 kN
== 1079.62 kN.m
=
=5522.696
= 5.1154 > 1.5 , Ok1079.621b. Check against Sliding
== 929.304 kN
=
m2 m3
Wt of conc. (WC)
Thrust (TW) 2PWAP sin q/2
Resisting Moment (MR) WC * x
Buoyant Force (BF) w * vol. sub.
Overturning Moment (MOT) TW * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Resisting Force (FR) (Wt. of Conc. - BF) * μ
Safety factor against sliding (FS)FR
TW
F.G.L.
h1
h2
x
y
O
WC
Tw
Figure 3: Diagram of forces on a horizontal thrust
GWT
Figure 2: Height of soil and the submerged height in a horizontal thrust block
BF
=929.304
= 1.7215 > 1.5 , Ok539.810
2. At Hydrotest Pressure - 9 bar
== 809.715 kN
a. Check against Overturning
== 1619.431 kN.m
=
=5522.696
= 3.4103 > 1.13 , Ok1619.431
b. Check against Sliding
=
=929.304
= 1.1477 > 1.13 , Ok809.715
3. Check against Bouyancy
=Wt. of Conc
=2323.260
= N/A > 1.2 , Ok0.000
FS
Thrust (TH) 2PHAP sin q/2
Overturning Moment (MOT) TH * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Safety factor against sliding (FS)FR
TH
FS
Safety factor against bouyancy (FB)BF
FB
THRUST BLOCKS FOR HORIZONTAL ELBOW ( Ø 900 mm, 60 deg )Horizontal Thrust
TABLE 1 DIMENSIONS IN mm FOR CONCRETE BLOCKSFOR 60 DEGREES BENDS - HORIZONTAL THRUST
L A B C D E F
900 1208 5110 442 6342 4000 1650 4250 67.796
steps 1 4 2 3
Design Parameters
= 900 mm= 60 deg= 0.6362
= 18
= 24
= 10Coefficient of friction (μ) = 0.40
= 0.150 m
= 0.000 m
At Working Pressure
= 6 bars = 600 FGL = + 9.000
= 1.50 IL = + 6.400
= 1.50 GWT = + 4.400
= 1.20
At Hydrotest Pressure
= 9 bars = 900
= 1.13
= 1.13
= 1.20
PIPE DIAMETER
(mm)CONC
VOL (m3)
Pipe Diameter (DP)Angle of the bend (q)
Area of Pipe (AP) m2
Unit weight of soil (gS) kN/m3
Unit weight of concrete (gC) kN/m3
Unit weight of water (w) kN/m3
Height of soil above thrust block (h1)
Submerged height of thrust block (h2)
Working Pressure (PW) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Working Pressure (PH) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Figure 1: Plan and Section for horizontal thrust block
G10
Robert.tan: Elbow Data given from FRP Table
Q10
Robert.tan: Note that E should be less than X1
Soil Bearing Capacity (SBC) = 100 kPa
Check on Soil Bearing Pressure
Thrust Block Plan Area = 17.333 Volume of soil = 2.600= 1627.101 kN (neglecting buoyancy) Wt of soil = 46.800 kN (on top of thrust block)
ΣV = Wt. of conc + Wt. of soil= 1673.900 kN
Static vertical pressure =ΣV
Plan Area96.572 kPa < SBC, Ok
Thrust Block Stability Check
1. At Working Pressure - 6 bar
== 381.704 kN
a. Check against OverturningTaking moments about O
x =A*(C+2B)
= 1.814 m3(B+C)y = D / 2 = 2.000 m
== 2951.920 kN.m
== 0.000 kN
== 763.407 kN.m
=
=2951.920
= 3.8668 > 1.5 , Ok763.407b. Check against Sliding
== 650.840 kN
m2 m3
Wt of conc. (WC)
Thrust (TW) 2PWAP sin q/2
Resisting Moment (MR) WC * x
Buoyant Force (BF) w * vol. sub.
Overturning Moment (MOT) TW * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Resisting Force (FR) (Wt. of Conc. - BF) * μ
F.G.L.
h1
h2
x
y
O
WC
Tw
Figure 3: Diagram of forces on a horizontal thrust
GWT
Figure 2: Height of soil and the submerged height in a horizontal thrust block
BF
=
=650.840
= 1.7051 > 1.5 , Ok381.704
2. At Hydrotest Pressure - 9 bar
== 572.555 kN
a. Check against Overturning
== 1145.111 kN.m
=
=2951.920
= 2.5778 > 1.13 , Ok1145.111
b. Check against Sliding
=
=650.840
= 1.1367 > 1.13 , Ok572.555
3. Check against Bouyancy
=Wt. of Conc
=1627.101
= N/A > 1.2 , Ok0.000
Safety factor against sliding (FS)FR
TW
FS
Thrust (TH) 2PHAP sin q/2
Overturning Moment (MOT) TH * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Safety factor against sliding (FS)FR
TH
FS
Safety factor against bouyancy (FB)BF
FB
THRUST BLOCKS FOR HORIZONTAL ELBOW ( Ø 900 mm, 45 deg )Horizontal Thrust
TABLE 1 DIMENSIONS IN mm FOR CONCRETE BLOCKSFOR 45 DEGREES BENDS - HORIZONTAL THRUST
L A B C D E F
900 1081 5174 467 4753 4000 2000 3600 52.633
steps 1 4 2 3
Design Parameters
= 900 mm= 45 deg= 0.6362
= 18
= 24
= 10Coefficient of friction (μ) = 0.40
= 0.150 m
= 0.000 m
At Working Pressure
= 6 bars = 600 FGL = + 9.000
= 1.50 IL = + 6.400
= 1.50 GWT = + 4.400
= 1.20
At Hydrotest Pressure
= 9 bars = 900
= 1.13
= 1.13
= 1.20
PIPE DIAMETER
(mm)CONC
VOL (m3)
Pipe Diameter (DP)Angle of the bend (q)
Area of Pipe (AP) m2
Unit weight of soil (gS) kN/m3
Unit weight of concrete (gC) kN/m3
Unit weight of water (w) kN/m3
Height of soil above thrust block (h1)
Submerged height of thrust block (h2)
Working Pressure (PW) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Working Pressure (PH) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Figure 1: Plan and Section for horizontal thrust block
G10
Robert.tan: Elbow Data given from FRP Table
Q10
Robert.tan: Note that E should be less than X1
Soil Bearing Capacity (SBC) = 100 kPa
Check on Soil Bearing Pressure
Thrust Block Plan Area = 13.502 Volume of soil = 2.025= 1263.180 kN (neglecting buoyancy) Wt of soil = 36.455 kN (on top of thrust block)
ΣV = Wt. of conc + Wt. of soil= 1299.636 kN
Static vertical pressure =ΣV
Plan Area96.255 kPa < SBC, Ok
Thrust Block Stability Check
1. At Working Pressure - 6 bar
== 292.143 kN
a. Check against OverturningTaking moments about O
x =A*(C+2B)
= 1.879 m3(B+C)y = D / 2 = 2.000 m
== 2373.234 kN.m
== 0.000 kN
== 584.286 kN.m
=
=2373.234
= 4.0618 > 1.5 , Ok584.286b. Check against Sliding
== 505.272 kN
m2 m3
Wt of conc. (WC)
Thrust (TW) 2PWAP sin q/2
Resisting Moment (MR) WC * x
Buoyant Force (BF) w * vol. sub.
Overturning Moment (MOT) TW * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Resisting Force (FR) (Wt. of Conc. - BF) * μ
F.G.L.
h1
h2
x
y
O
WC
Tw
Figure 3: Diagram of forces on a horizontal thrust
GWT
Figure 2: Height of soil and the submerged height in a horizontal thrust block
BF
=
=505.272
= 1.7295 > 1.5 , Ok292.143
2. At Hydrotest Pressure - 9 bar
== 438.215 kN
a. Check against Overturning
== 876.430 kN.m
=
=2373.234
= 2.7078 > 1.13 , Ok876.430
b. Check against Sliding
=
=505.272
= 1.153 > 1.13 , Ok438.215
3. Check against Bouyancy
=Wt. of Conc
=1263.180
= N/A > 1.2 , Ok0.000
Safety factor against sliding (FS)FR
TW
FS
Thrust (TH) 2PHAP sin q/2
Overturning Moment (MOT) TH * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Safety factor against sliding (FS)FR
TH
FS
Safety factor against bouyancy (FB)BF
FB
THRUST BLOCKS FOR HORIZONTAL ELBOW ( Ø 900 mm, 30 deg )Horizontal Thrust
TABLE 1 DIMENSIONS IN mm FOR CONCRETE BLOCKSFOR 30 DEGREES BENDS - HORIZONTAL THRUST
L A B C D E F
900 790 4975 491 3157 4000 2000 3150 35.285
steps 1 4 2 3
Design Parameters
= 900 mm= 30 deg= 0.6362
= 18
= 24
= 10Coefficient of friction (μ) = 0.40
= 0.150 m
= 0.000 m
At Working Pressure
= 6 bars = 600 FGL = + 9.000
= 1.50 IL = + 6.400
= 1.50 GWT = + 4.400
= 1.20
At Hydrotest Pressure
= 9 bars = 900
= 1.13
= 1.13
= 1.20
PIPE DIAMETER
(mm)CONC
VOL (m3)
Pipe Diameter (DP)Angle of the bend (q)
Area of Pipe (AP) m2
Unit weight of soil (gS) kN/m3
Unit weight of concrete (gC) kN/m3
Unit weight of water (w) kN/m3
Height of soil above thrust block (h1)
Submerged height of thrust block (h2)
Working Pressure (PW) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Working Pressure (PH) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Figure 1: Plan and Section for horizontal thrust block
G10
Robert.tan: Elbow Data given from FRP Table
Q10
Robert.tan: Note that E should be less than X1
Soil Bearing Capacity (SBC) = 100 kPa
Check on Soil Bearing Pressure
Thrust Block Plan Area = 9.073 Volume of soil = 1.361= 846.841 kN (neglecting buoyancy) Wt of soil = 24.496 kN (on top of thrust block)
ΣV = Wt. of conc + Wt. of soil= 871.337 kN
Static vertical pressure =ΣV
Plan Area96.041 kPa < SBC, Ok
Thrust Block Stability Check
1. At Working Pressure - 6 bar
== 197.584 kN
a. Check against OverturningTaking moments about O
x =A*(C+2B)
= 1.881 m3(B+C)y = D / 2 = 2.000 m
== 1593.184 kN.m
== 0.000 kN
== 395.169 kN.m
=
=1593.184
= 4.0317 > 1.5 , Ok395.169b. Check against Sliding
== 338.736 kN
m2 m3
Wt of conc. (WC)
Thrust (TW) 2PWAP sin q/2
Resisting Moment (MR) WC * x
Buoyant Force (BF) w * vol. sub.
Overturning Moment (MOT) TW * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Resisting Force (FR) (Wt. of Conc. - BF) * μ
F.G.L.
h1
h2
x
y
O
WC
Tw
Figure 3: Diagram of forces on a horizontal thrust
GWT
Figure 2: Height of soil and the submerged height in a horizontal thrust block
BF
=
=338.736
= 1.7144 > 1.5 , Ok197.584
2. At Hydrotest Pressure - 9 bar
== 296.376 kN
a. Check against Overturning
== 592.753 kN.m
=
=1593.184
= 2.6878 > 1.13 , Ok592.753
b. Check against Sliding
=
=338.736
= 1.1429 > 1.13 , Ok296.376
3. Check against Bouyancy
=Wt. of Conc
=846.841
= N/A > 1.2 , Ok0.000
Safety factor against sliding (FS)FR
TW
FS
Thrust (TH) 2PHAP sin q/2
Overturning Moment (MOT) TH * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Safety factor against sliding (FS)FR
TH
FS
Safety factor against bouyancy (FB)BF
FB
THRUST BLOCKS FOR HORIZONTAL ELBOW ( Ø 900 mm, 22.5 deg )Horizontal Thrust
TABLE 1 DIMENSIONS IN mm FOR CONCRETE BLOCKSFOR 22.5 DEGREES BENDS - HORIZONTAL THRUST
L A B C D E F
900 790 3923 964 2525 4000 1500 2500 26.374
steps 1 4 2 3
Design Parameters
= 900 mm= 22.5 deg= 0.6362
= 18
= 24
= 10Coefficient of friction (μ) = 0.40
= 0.150 m
= 0.000 m
At Working Pressure
= 6 bars = 600 FGL = + 9.000
= 1.50 IL = + 6.400
= 1.50 GWT = + 4.400
= 1.20
At Hydrotest Pressure
= 9 bars = 900
= 1.13
= 1.13
= 1.20
PIPE DIAMETER
(mm)CONC
VOL (m3)
Pipe Diameter (DP)Angle of the bend (q)
Area of Pipe (AP) m2
Unit weight of soil (gS) kN/m3
Unit weight of concrete (gC) kN/m3
Unit weight of water (w) kN/m3
Height of soil above thrust block (h1)
Submerged height of thrust block (h2)
Working Pressure (PW) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Working Pressure (PH) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Figure 1: Plan and Section for horizontal thrust block
G10
Robert.tan: Elbow Data given from FRP Table
Q10
Robert.tan: Note that E should be less than X1
Soil Bearing Capacity (SBC) = 100 kPa
Check on Soil Bearing Pressure
Thrust Block Plan Area = 6.845 Volume of soil = 1.027= 632.980 kN (neglecting buoyancy) Wt of soil = 18.481 kN (on top of thrust block)
ΣV = Wt. of conc + Wt. of soil= 651.461 kN
Static vertical pressure =ΣV
Plan Area95.176 kPa < SBC, Ok
Thrust Block Stability Check
1. At Working Pressure - 6 bar
== 148.933 kN
a. Check against OverturningTaking moments about O
x =A*(C+2B)
= 1.669 m3(B+C)y = D / 2 = 2.000 m
== 1056.520 kN.m
== 0.000 kN
== 297.867 kN.m
=
=1056.520
= 3.547 > 1.5 , Ok297.867b. Check against Sliding
== 253.192 kN
m2 m3
Wt of conc. (WC)
Thrust (TW) 2PWAP sin q/2
Resisting Moment (MR) WC * x
Buoyant Force (BF) w * vol. sub.
Overturning Moment (MOT) TW * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Resisting Force (FR) (Wt. of Conc. - BF) * μ
F.G.L.
h1
h2
x
y
O
WC
Tw
Figure 3: Diagram of forces on a horizontal thrust
GWT
Figure 2: Height of soil and the submerged height in a horizontal thrust block
BF
=
=253.192
= 1.7 > 1.5 , Ok148.933
2. At Hydrotest Pressure - 9 bar
== 223.400 kN
a. Check against Overturning
== 446.800 kN.m
=
=1056.520
= 2.3646 > 1.13 , Ok446.800
b. Check against Sliding
=
=253.192
= 1.1334 > 1.13 , Ok223.400
3. Check against Bouyancy
=Wt. of Conc
=632.980
= N/A > 1.2 , Ok0.000
Safety factor against sliding (FS)FR
TW
FS
Thrust (TH) 2PHAP sin q/2
Overturning Moment (MOT) TH * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Safety factor against sliding (FS)FR
TH
FS
Safety factor against bouyancy (FB)BF
FB
THRUST BLOCKS FOR HORIZONTAL ELBOW ( Ø 900 mm, 11.25 deg )Horizontal Thrust
TABLE 1 DIMENSIONS IN mm FOR CONCRETE BLOCKSFOR 11.25 DEGREES BENDS - HORIZONTAL THRUST
L A B C D E F
900 790 2836 1406 1964 3000 850 2000 13.333
steps 1 4 2 3
Design Parameters
= 900 mm= 11.25 deg= 0.6362
= 18
= 24
= 10Coefficient of friction (μ) = 0.40
= 0.650 m
= 0.000 m
At Working Pressure
= 6 bars = 600 FGL = + 9.000
= 1.50 IL = + 6.400
= 1.50 GWT = + 4.400
= 1.20
At Hydrotest Pressure
= 9 bars = 900
= 1.13
= 1.13
= 1.20
PIPE DIAMETER
(mm)CONC
VOL (m3)
Pipe Diameter (DP)Angle of the bend (q)
Area of Pipe (AP) m2
Unit weight of soil (gS) kN/m3
Unit weight of concrete (gC) kN/m3
Unit weight of water (w) kN/m3
Height of soil above thrust block (h1)
Submerged height of thrust block (h2)
Working Pressure (PW) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Working Pressure (PH) kN/m2
Factor of Safety against Overturning (FOT)
Factor of Safety against Sliding (FS)
Factor of Safety against Buoyancy (FB)
Figure 1: Plan and Section for horizontal thrust block
G10
Robert.tan: Elbow Data given from FRP Table
Q10
Robert.tan: Note that E should be less than X1
Soil Bearing Capacity (SBC) = 100 kPa
Check on Soil Bearing Pressure
Thrust Block Plan Area = 4.779 Volume of soil = 3.107= 319.996 kN (neglecting buoyancy) Wt of soil = 55.919 kN (on top of thrust block)
ΣV = Wt. of conc + Wt. of soil= 375.916 kN
Static vertical pressure =ΣV
Plan Area78.653 kPa < SBC, Ok
Thrust Block Stability Check
1. At Working Pressure - 6 bar
== 74.827 kN
a. Check against OverturningTaking moments about O
x =A*(C+2B)
= 1.340 m3(B+C)y = D / 2 = 1.500 m
== 428.723 kN.m
== 0.000 kN
== 112.240 kN.m
=
=428.723
= 3.8197 > 1.5 , Ok112.240b. Check against Sliding
== 127.998 kN
m2 m3
Wt of conc. (WC)
Thrust (TW) 2PWAP sin q/2
Resisting Moment (MR) WC * x
Buoyant Force (BF) w * vol. sub.
Overturning Moment (MOT) TW * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Resisting Force (FR) (Wt. of Conc. - BF) * μ
F.G.L.
h1
h2
x
y
O
WC
Tw
Figure 3: Diagram of forces on a horizontal thrust
GWT
Figure 2: Height of soil and the submerged height in a horizontal thrust block
BF
=
=127.998
= 1.7106 > 1.5 , Ok74.827
2. At Hydrotest Pressure - 9 bar
== 112.240 kN
a. Check against Overturning
== 168.361 kN.m
=
=428.723
= 2.5465 > 1.13 , Ok168.361
b. Check against Sliding
=
=127.998
= 1.1404 > 1.13 , Ok112.240
3. Check against Bouyancy
=Wt. of Conc
=319.996
= N/A > 1.2 , Ok0.000
Safety factor against sliding (FS)FR
TW
FS
Thrust (TH) 2PHAP sin q/2
Overturning Moment (MOT) TH * y + BF * x
Safety factor against overturing (FOT)MR
MOT
FOT
Safety factor against sliding (FS)FR
TH
FS
Safety factor against bouyancy (FB)BF
FB
