PIPELINE STABILITY & BUOYANCY CONTROL CALCULATION 1.0 BASE DATA PIPELINE DIA (STEEL) INCH LINEPIPE WALL THICKNESS STEEL SPECIFIC GRAVITY CORROSION COATING (3LPE) THICKNESS
D t Ss tcc
CORROSION COATING (3LPE) SPECIFIC GRAVITY
CCs
PRODUCT SPECIFIC GRAVITY, SRR
Ps
SLURRY SPECIFIC GRAVITY
SWs
WATER (PIPELINE FILL) SPECIFIC GRAVITY
FWww
SATURATED SOIL SPECIFIC GRAVITY COVER TO TOP OF PIPE DENSITY OF CONCRETE STEEL SPECIFIC WEIGHT
SSs h
CORROSION COATING SPECIFIC WEIGHT
Wtcc
PRODUCT SPECIFIC WEIGHT
Wtpr
SLURRY SPECIFIC WEIGHT
Wtw
WATER SPECIFIC WEIGHT
Wtww
SATURATED SOIL SPECIFIC WEIGHT
Wtss
SATURATED SOIL,20% FLUIDISED, SPECIFIC WEIGHT (80%Wtss)
Wtsf
Wtst
2.0 OVERBURDEN FROM BACKFILL CALCULATIONS FULL OUTSIDE DIAMETER, Do = D + 2tcc
Do
2.1 SATURATED OVERBURDEN, UNFLUIDIZED, CONDITION SPECIFIC WEIGHT OF SUBMERGED OVERBURDEN, Wtsss = Wtss - Wtw
Wtsss
FORCE EXERTED BY OVERBURDEN, Wtsoil = Wtsss * h * Do
Wtsoil
2.2 SATURATED OVERBURDEN, 20% FLUIDISED CONDITION SPECIFIC WEIGHT OF FLUIDISED OVERBURDEN, Wtssf = Wtsf - Wtw
Wtssf
FORCE EXERTED BY SATURATED FLUIDISED OVERBURDEN, Wtsoilf = Wtssf * h * Do
Wtsoilf
3.0 PIPELINE WEIGHT CALCULATIONS
3.1 PIPE WEIGHT,Ws = (p/4) * (D2- (D - 2t)2) * Wtst
Ws
3.2 WEIGHT OF CORROSION COATING, Wc = (p/4) * ((D + 2tcc)2-D2) * Wtcc
Wc
3.3 WEIGHT OF PIPE EMPTY, We = Ws + Wc
We
3.4 WEIGHT OF PRODUCT IN PIPELINE, Wpp = ( p/4) * (D - 2t)2 * Wtpr
Wpp
3.5 WEIGHT OF PIPELINE PRODUCT FILLED, Wp = We + Wpp
Wp
3.6 WEIGHT OF WATER IN PIPELINE, Www = ( p/4) * (D - 2t)2 * Wtww
Www
3.7 WEIGHT OF PIPELINE WATER FILLED, Wcw = We + Www
Wcw
3.8 UPLIFT FORCE, Wq = (p/4) * Do2 * Wtw
Wq
4.0 STABILITY ASSESSMENT , PIPELINE EMPTY 4.1 SUBMERGED WEIGHT, UNFLUIDISED, Wse Wse = We - Wq + Wtsoil
FACTOR OF SAFETY AGAINST UPLIFT, FOS FOS = (We + Wtsoil)/Wq 4.2 SUBMERGED WEIGHT, FLUIDISED, Wsef Wsef = We - Wq + Wtsoilf
FACTOR OF SAFETY AGAINST UPLIFT, FOS FOS = (We + Wtsoilf)/Wq
Wse >=0
FOS
Wsef <0
FOS
SINCE IT IS NOT STABLE WHEN PIPELINE IS EMPTY, THUS, REQUIRES CONCRETE WEIGHT
5.0 STABILITY ASSESSMENT, PRODUCT FILLED PIPELINE 5.1 SUBMERGED WEIGHT, UNFLUIDISED, Wsf Wsf = Wp - Wq + Wtsoil
FACTOR OF SAFETY AGAINST UPLIFT, FOS
Wsf >=0
FOS = (Wp + Wtsoil)/Wq 5.2 SUBMERGED WEIGHT, FLUIDISED, Wsff Wsff = Wp - Wq + Wtsoilf
FACTOR OF SAFETY AGAINST UPLIFT, FOS FOS = (Wp + Wtsoilf)/Wq
FOS
Wsff >=0
FOS
6.0 PIPELINE STABILITY IN UNFILLED TRENCH 6.1 CHECK EMPTY CASE TO BE STABLE CHECK We ≥ Wq 6.2 CHECK WATER FILLED CASE TO BE STABLE CHECK Wcw ≥ Wq
4.1304
12.3846
OPTION I - CALCULATION OF SADDLE BLOCK ADDITIONAL 20% SF OF BUOYANCY FORCE = 1.2 Wq
1.2 Wq
NET UPWARD FORCE = 1.2 BUOYANCY FORCE - PIPE WEIGHT = 1.2 Wq - We USE CONCRETE SADDLE AT A SPACING OF : TOTAL UPLIFT FORCE IN ONE SADDLE = NET UPWARD FORCE * SADDLE SPACING SADDLE BLOCK DIMENSION SIDE SLAB THICKNESS, tside
tside
TOP SLAB THICKNESS, ttop LENGTH WIDTH, b = Do + ( 2 * tside ) = b C/S AREA OF SADDLE SUBMERGED WEIGHT OF SADLE BLOCK
ttop L b
OPTION II - CALCULATION OF CONTINUOUS CONCRETE PROTECTION ADDITIONAL 20% SF OF BUOYANCY FORCE = 1.2 Wq NET UPWARD FORCE = 1.2 BUOYANCY FORCE - PIPE WEIGHT = 1.2 Wq - We
1.2 Wq
C/S AREA REQUIRED = NET UPWARD FORCE / SPECIFIC DENSITY OF CONCRETE OUTER DIAMETER REQUIRED, Dp MINIMUM CONCRETE PROTECTION THICKNESS = ( Dp - Do) / 2 SELECTED CONTINUOUS CONCRETE PROTECTION THICKNESS (FOR STABILITY) ADDING 20% MARGIN
42 1.0668 0.01588 7.85 0.003
INCH Meters Meters
1066.8 mm 15.88 mm
Meters
3 mm
0.94 0.905
1200
1.025
0.02
1
1004
1.5 1.2 Meters 30 kN/m3 3 77.01 kN/m 3 9.22 kN/m
1.5 0.2 1
3 8.88 kN/m 3 10.06 kN/m 3 9.81 kN/m 3 14.72 kN/m
11.772 kN/m
3
1.073 Meters
3 4.66 kN/m
6.00 kN/m run of pipe
3 1.72 kN/m
2.21 kN/m run of pipe
1.2
4.0375 kN/m run of pipe 0.0930 kN/m run of pipe 4.1304 kN/m run of pipe 7.470019501 kN/m run of pipe 11.6005 kN/m run of pipe 8.254165194 kN/m run of pipe 12.3846 kN/m run of pipe 9.089087489 kN/m run of pipe
1.0401 kN/m run of pipe therefore stable
1.114437064
-2.7486 kN/m run of pipe NO, THEREFORE NOT STABLE
0.70
8.5101 kN/m run of pipe therefore stable
1.94
4.7214 kN/m run of pipe
therefore stable
1.52
<
9.08909 UNSTABLE
>=
9.08909 THEREFORE STABLE
10.90690499 kN/m run of pipe 6.7765 kN/m run of pipe 6 Meters 40.659 kN 1.5025 1.2 1.803
0.4 m 0.6 m 1.2 m 1.873 m ???? ???
10.90690499 kN/m run of pipe 6.7765 kN/m run of pipe
1.02003 1.2234
7.98204
0.226 m2
1.803
1.199375645 0.063287822 M
76 mm
0.127 0.06329 63.2878
0.1564 0.0782
9.81019 77.01
0.4 1.3365 1.073 1.873 1.473 1.7676
0.22599
1.14467 1.19933 0.67393
0.6911
-0.0237 0.22588
1.20086 1.19968 1.44065
1.3553
