Safety Valve Calc
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Transcript of Safety Valve Calc
Safety valve nozzle M/S.CETHAR VESSELS (P ) LTDM/S.BINANI CEMENTS
Date:-02-09-06Rev:-00 .
Prepared by Verified by Approved by .
SAFETY VALVE NOZZLE DESIGN CALCULATION AS PER ASME B31.1-2010
Description Input Unit
Safety valve set pressure = P 289.30
Design temperature 471.00 °C
Nozzle material specification SA182 F12CL2 -
Young's Modulus of material @ design temp = E 2.48E+07 psi
Allowable stress for saf.valve nozz.matl @ design t 18200.00 psi
Weight of valve = W 422.00 kgs
Nozzle height from od of run pipe = H2 154.94 mm
Dist. betw. od of run pipe to centre line outlet pipe 484.94 mm
Run pipe outside diameter =O.D 273.00 mm
Thickness of run pipe = Tr 33.90 mm
Saf. valve nozz.od @ pipe conn (point-1) = dn1.=2r 204.00 mm
Saf. valve nozz.thk @pipe conn (point-1) = T'b. 63.15 mm
Saf. valve nozz.od @ valve conn (point-2) = dn2. 204.00 mm
Saf. valve nozz.thk @ valve conn (point-2) = tn2. 62.49 mm
Valve rise time = to 0.04 sec
Moment arm = L 610.00 mm
Moment arm for point (1) =L1 19 inch
Moment arm for point (2) =L2 13 inch
Seismic coefficient 1.5 -
Average od of saf.valve nozzle = do 8.031 inch
Average id of saf.valve nozzle = di 3.06 inch
Moment of inertia of saf.valve nozzle = I 199.95
0.006669 sec
Ratio = to/ T 6.00 -
Dynamic load factor (fig II.3.2 of apx.-II of asme b31 1.11 -
BENDING MOMENTS AT POINTS (1) & (2)
Reaction force @ discharge elbow exit = F1 8026.30 kg
471570.83 in-lb
Seismic force = Fs = mass x acceleration 1395 lbf
Bend.moment @ pt 1due to seismic force =Ms(1) = 26505 in-lb
Bend.moment @ pt 2 due to seismic force =Ms(2) = 18135 in-lb
Combined bend.moment @ pt 1 = M1 = M1(1) + Ms 498075.83 in-lb
Combined bend.moment @ pt 2 = M2 = M1(2) + Ms 489705.83 in-lb
Mean radius of run pipe = Rm 4.707 inch
Mean radius of saf valve nozzle @ pt 1 = r'm 2.773 inch
STRESS INTENSIFICATION FACTORS AT POINTS (1 )& ( 2)
Outer radius of saf valve nozz @ pt 1 = rp 4.02 inch
3.43 -
Stress intensification factor for pt 2 (butt weld) = i(2 1.00 -
kg/cm2
inch4
Safety valve installation period = T = 0.1846 x √(Wh3/EI)
Bending moment @ pt 1& 2 due to force F1=M1(1)& M1(2) = F1 X L X DLF
Stress intensification factor for pt 1 (branch conn) = i(1) = ((Rm/Tr)^2/3)x(r'm/Rm)^0.5 x (T'b/ Tr) x (r'm/rp)
Safety valve nozzle M/S.CETHAR VESSELS (P ) LTDM/S.BINANI CEMENTS
Date:-02-09-06Rev:-00 .
Prepared by Verified by Approved by .
PREDICTED STRESSES AT POINT (1) - BRANCH CONNECTION
Ratio = Do/ Tr for run pipe 8.05 -
Ratio = dn1/ T'b for safety valve nozzle 3.23040380048 -
ts = lesser of Tr or (i1)T'b 1 inch
rb = r'm 2.773 inch
Section modulus of point (1) =Z1= π rb^2 ts 32.00
Pressure stress(1) for branch conn. =Ps(1) 8282.30 psi
40040.63 psi
PREDICTED STRESSES AT POINT (2) - BUTT WELD
Ratio = dn1/ tn2 for safety valve nozzle 3.26 -
49.79
Pressure stress(2) for butt weld =Ps(2) 3357.44 psi
Factor 0.75 x i(2) 0.75 -
1 -
9835.21 psi
COMPARISON OF PREDICTED STRESS WITH ALLOWABLE STRESS
Increase factor for hot allowable stress = k 1.20 -
Allowable hot stress @ design temp = k x Sh 21840.00 psi
48322.93 psi
13192.64 psi
Comb stress(1) condition check Cs(1) <= (k x Sh) NOT SAFE -
Comb stress(2) condition check Cs(2 )<= (k x Sh) SAFE -
inch3
Flexure stress(1) for branch connection = Fs(1)=(0.75x i(1)x M(1))/ Z(1)
Section modulus of point (2) =Z2= (π/32) x (dn2^4- di^4)/dn2 inch3
If factor 0.75x i(2) is less than 1.0 it should be taken as 1.0
Flexure stress(2) for butt weld = Fs(2)=(0.75x i(2)x M(2))/ Z(2)
Combined stress at point (1) branch conn = Cs(1)= Pr.stress Ps(1) +Flex.stress Fs(1)
Combined stress at point (2) butt weld =Cs(2) = Pr.stress Ps(2) + Flex.stress Fs(2)
Safety valve nozzle M/S.CETHAR VESSELS (P ) LTDM/S.BINANI CEMENTS
Date:-02-09-06Rev:-00 .
Prepared by Verified by Approved by .
SAFETY VALVE NOZZLE DESIGN CALCULATION AS PER ASME B31.1-2010
Description Input Unit
Safety valve set pressure = P 270.30
Design temperature 573.60 °C
Nozzle material specification SA182 F12CL2 -
Young's Modulus of material @ design temp = E 2.48E+07 psi
Allowable stress for saf.valve nozz.matl @ design t 4000.00 psi
Weight of valve = W 422.00 kgs
Nozzle height from od of run pipe = H2 200.00 mm
Dist. betw. od of run pipe to centre line outlet pipe 520.00 mm
Run pipe outside diameter =O.D 273.00 mm
Thickness of run pipe = Tr 34.10 mm
Saf. valve nozz.od @ pipe conn (point-1) = dn1.=2rp 184.20 mm
Saf. valve nozz.thk @pipe conn (point-1) = T'b. 59.60 mm
Saf. valve nozz.od @ valve conn (point-2) = dn2. 184.20 mm
Saf. valve nozz.thk @ valve conn (point-2) = tn2. 58.80 mm
Valve rise time = to 0.04 sec
Moment arm = L 610.00 mm
Moment arm for point (1) =L1 20 inch
Moment arm for point (2) =L2 13 inch
Seismic coefficient 1.5 -
Average od of saf.valve nozzle = do 7.252 inch
Average id of saf.valve nozzle = di 2.56 inch
Moment of inertia of saf.valve nozzle = I 133.66
0.009058 sec
Ratio = to/ T 4.42 -
Dynamic load factor (fig II.3.2 of apx.-II of asme b31 1.15 -
BENDING MOMENTS AT POINTS (1) & (2)
Reaction force @ discharge elbow exit = F1 9297.74 kg
565950.31 in-lb
Seismic force = Fs = mass x acceleration 1395 lbf
Bend.moment @ pt 1due to seismic force =Ms(1) = 27900 in-lb
Bend.moment @ pt 2 due to seismic force =Ms(2) = 18135 in-lb
Combined bend.moment @ pt 1 = M1 = M1(1) + Ms( 593850.31 in-lb
Combined bend.moment @ pt 2 = M2 = M1(2) + Ms( 584085.31 in-lb
Mean radius of run pipe = Rm 4.703 inch
Mean radius of saf valve nozzle @ pt 1 = r'm 2.453 inch
STRESS INTENSIFICATION FACTORS AT POINTS (1 )& ( 2)
Outer radius of saf valve nozz @ pt 1 = rp 3.63 inch
2.95 -
Stress intensification factor for pt 2 (butt weld) = i(2 1.00 -
PREDICTED STRESSES AT POINT (1) - BRANCH CONNECTION
Ratio = Do/ Tr for run pipe 8.01 -
Ratio = dn1/ T'b for safety valve nozzle 3.09060402685 -
ts = lesser of Tr or (i1)T'b 1 inch
rb = r'm 2.453 inch
kg/cm2
inch4
Safety valve installation period = T = 0.1846 x √(Wh3/EI)
Bending moment @ pt 1& 2 due to force F1=M1(1)& M1(2) = F1 X L X DLF
Stress intensification factor for pt 1 (branch conn) = i(1) = ((Rm/Tr)^2/3)x(r'm/Rm)^0.5 x (T'b/ Tr) x (r'm/rp)
Safety valve nozzle M/S.CETHAR VESSELS (P ) LTDM/S.BINANI CEMENTS
Date:-02-09-06Rev:-00 .
Prepared by Verified by Approved by .
Section modulus of point (1) =Z1= π rb^2 ts 25.00
Pressure stress(1) for branch conn. =Ps(1) 7692.97 psi
52555.75 psi
PREDICTED STRESSES AT POINT (2) - BUTT WELD
Ratio = dn1/ tn2 for safety valve nozzle 3.13 -
36.86
Pressure stress(2) for butt weld =Ps(2) 3010.22 psi
Factor 0.75 x i(2) 0.75 -
1 -
15845.12 psi
COMPARISON OF PREDICTED STRESS WITH ALLOWABLE STRESS
Increase factor for hot allowable stress = k 1.20 -
Allowable hot stress @ design temp = k x Sh 4800.00 psi
60248.72 psi
18855.34 psi
Comb stress(1) condition check Cs(1) <= (k x Sh) NOT SAFE -
Comb stress(2) condition check Cs(2 )<= (k x Sh) NOT SAFE -
inch3
Flexure stress(1) for branch connection = Fs(1)=(0.75x i(1)x M(1))/ Z(1)
Section modulus of point (2) =Z2= (π/32) x (dn2^4- di^4)/dn2 inch3
If factor 0.75x i(2) is less than 1.0 it should be taken as 1.0
Flexure stress(2) for butt weld = Fs(2)=(0.75x i(2)x M(2))/ Z(2)
Combined stress at point (1) branch conn = Cs(1)= Pr.stress Ps(1) +Flex.stress Fs(1)
Combined stress at point (2) butt weld =Cs(2) = Pr.stress Ps(2) + Flex.stress Fs(2)
Safety valve nozzle M/S.CETHAR VESSELS (P ) LTDM/S.BINANI CEMENTS
Date:-02-09-06Rev:-00 .
Prepared by Verified by Approved by .
NONMANDATORY Rules for the design of saftey valve installation
a Design pressure and velocity
P inlet pressure (Absolute) 925 psi
T Inlet tempereature 1000
Atmospheric pressure 15 psia
W Weight of the valve 800 lb From SV data sheet
Valve opening time 0.04 sec From SV data sheet
Discharge elbow area 50.03
Gravitational constant 32.2
1507.30 Btu/lbm From steam tables
j constant 778.16 Btu/lbm
W Actual mass flow rate 116.38 lbm/sec
Pressure @ the discharge elbow 118 psia
Velocity @ the discharge elbow 2116 ft/sec
B Discharge Elbow max operating pressure
For 8 in. class 150 ASME Weld neck flange
L 4 in Σ (L/D) =D 7.981 in 32.00
L/D 0.50 f 0.013
k 1.3For 8 in. SCH 40 short radius elbow
L/D 30 0.416
For 12 in. of 8 in. SCH 40 pipe, 1.647
L 12
D 7.981 194 psiaL/D 1.50
C Recation force at Discharge elbow Exit
12778 lbf
oF
Pa
t0
A1 in 2
gc lm-ft/lbf-sec2
hoStagnation enthalpy @ the safety valve inlet
P1
V1
(Lmax/D)
f(Lmax/D)
From tabel P/P*
P1a = P1 (P/P*)P1a =
F1
D Bending Moment at points (1) and (2)
(A)Bending moment at the point (1) & (2) due to recation at point (1)
= F1 x L x DLFL moment arm 24.00 in
DFL Dynamic load factor 1.11 from graph
To Find DFL
E = Youngs modulus of inlet pipe @ design temp 23000000 Psi
h = distance from run pipe to centerline of outlet piping 19 in
I = Moment of inertia of inlet pipe OD 9.875 inID 6 inI 403
Bending moment T 0.0045 sec
For a valve rise time
340407.23 in-lb
(A) Bending moment at the point (1) & (2) due to Seismic loading
Acceleration 1.5 Data fron structure
mass x acceleration
1200 lbf
moment arm for point (1) 19 in
22800 in-lb
moment arm for point (2) 12 in
14400 in-lb
(c) Bending moment at the point (1) & (2) due to Seismic loading
363207.23 in-lb
354807.23 in-lb
M1(1) = M1(2)
in4
M1(1) = M1(2)
M1(1) = M1(2)
Fs =
Fs =
MS(1)
MS(2)
M(1) = M1(1) + MS(1)
M(2) = M1(2) + MS(2)
steam condition a, Btu/ibm b
1 291 11a
2 823 4.33b
3 831 4.33
wet steam< 90 % qualitySaturated steam ≥
90 % quality 15 psia ≤ p1 ≤ 1,000
psia
superheated steam ≥ 90 % quality 1000 psia ≤ p1 ≤ 2,000 psia
8234.33
Metal-200 -129 -73 21 93 149 204 260
-325 -200 -100 70 200 300 400 500
Cast iron
Gray cast iron 13.4 13.2 12.9 12.6 12.2
Steel
31.4 30.8 30.2 29.5 28.8 28.3 27.7 27.3
31.2 30.6 30 29.3 28.6 28.1 27.5 27.1
Carbon-moly steels 31.1 30.5 29.9 29.2 28.5 28 27.4 27
29.6 29.1 28.5 27.8 27.1 26.7 26.1 25.7
31.6 31 30.4 29.7 29 28.5 27.9 27.5
32.6 32 31.4 30.6 29.8 29.4 28.8 28.3
32.9 32.3 31.7 30.9 30.1 29.7 29 28.6
31.2 30.7 30.1 29.2 28.5 27.9 27.3 26.7
30.3 29.7 29.1 28.3 27.6 27 26.5 25.8
Young Modulus of Elasticity - E - (106 psi)
Temperature (oC)
Temperature (oF)
Carbon steel C <= 0.3%
Carbon steel C => 0.3%
Nickel steels Ni 2% - 9%
Cr-Mo steels Cr 1/2% - 2%
Cr-Mo steels Cr 2 1/4% - 3%
Cr-Mo steels Cr 5% - 9%
Chromium steels Cr 12%, 17%, 27%
Austenitic steels (TP304, 310, 316,
321, 347)
316 371 427 482 538 593 649
600 700 800 900 1000 1100 1200
Cast iron
11.7 11 10.2
Steel
26.7 25.5 24.2 22.4 20.4 18
26.5 25.3 24 22.2 20.2 17.9 15.4
26.4 25.3 23.9 22.2 20.1 17.8 15.3
25.2 24.6 23
26.9 26.3 25.5 24.8 23.9 23 21.8
27.7 27.1 26.3 25.6 24.6 23.7 22.5
28 27.3 26.1 24.7 22.7 20.4 18.2
26.1 25.6 24.7 23.2 21.5 19.1 16.6
25.3 24.8 24.1 23.5 22.8 22.1 21.2
Young Modulus of Elasticity - E - (106 psi)
Temperature (oC)
Temperature (oF)