CALCULATION COVER SHEET
CLIENT:- Litwin Italy LAST PAGE
PAGE COUNT SUMMERY:
PROJECT NAME:- SUMMERY
PHOSPHORIC ACID PLANT TOTAL CALC. BODY PAGES: 4
CALCULATION TTITLE:- TOTAL ATTACH PAGES: 1 7
Determination of the magnitude of the water TOTAL PAGES: 7
pressure surge load
REF. CALCULATION NUMBER : LTW - 6210 - 0142 - P01
PROJECT or W.O NO DISCIPLINE CODE SEQUENCE NO REV NO
1000500 PI 0142_A P01
REVIWER/CHECKER CONFIRMATION
REV. PREPARER PRINTED REVISION REQUIRED
REV. DATE PRINTED NAME
NO. NAME AND SIGNATURE DESCRIPTION
AND SIGNATURE
YES NO
S.H.D. S.K.
FOR
P01 09 / 03 / 2009
INFORMATION
TABLE OF CONTENTS
1 CALCULATION OBJECTIVE 3
2 REFERANCES 3
2.1 REFERANCES 1 3
3 INPUTS 3
4 ASSUMPTIONS 3
4.1 ASSUMPTIONS 1 3
5 BASIS / METHODOLOGY 4
6 CONFIRMATION REQUIRED 5
6.1 1ST CONFIRMATION ITEM 5
7 COMPUTER CODE IDENTIFICATION 5
8 CALCULATION 5
9 RESULTS & CONCLUSIONS 6
Attachments Number of Pages Last page Number
Attachments A 1 7
Attachments B 0 0
TABLE OF CONTENTS
REF. CALCULATION NUMBER : LTW - 6210 - 0142 - P01
PROJECT or W.O
DISCIPLINE CODE SEQUENCE NO DATE PAGE NO
NO
1000500 PI 0142_A 09 / 03 / 2009
1. CALCULATION OBJECTIVE :-
Determination of the magnitude of the water hammer pressure surge, when the pump drops offline
due to supply trip
2. REFERENCES :-
2.1 REFERENCES 1
A) Version 5.00 CAESAR II Application guide
B) Version 5.00 CAESAR II User guide
C) Piping and Instrumentation Diagram (MD-502-6210-EG-PR-PID-0002-C01)
D) Pump Data Sheet (MD-502-6210-ME-GEA-0008-0001-P02)
E) Stress Critical Line List (RLT-1000500-LTW-PI-LST-0001 Dated 07 March 2009)
3. INPUTS :-
1) Design Flow rate of fluid
Q DESIGN = 25000 m3 / Hr
2) Bulk Modulus of fluid
Ef= 22005 Kg / cm2 = 2.2E+08 Kg / m2
3 Density of fluid
ρ= 1000 Kg / m3
3) Modulus of elasticity of the pipe material (FRP Pipe)
E = 224974 Kg / cm2 = 2.2E+09 Kg / m2
4) Diameter & thickness matrix for system
D (NPS) = 80 56 48 40 32
t (m) = 0.105 0.0417 0.0313 0.0266 0.0234
5) The length of pipe between adjacent elbow-elbow pairs
Elbow pairs A-B B-C C-D D-E E-F F-G
L (m) 31.8 28.7 11.1 7.8 14.4 48
4. ASSUMPTION :-
4.1 ASSUMPTIONS 1 :- Not applicable
REF. CALCULATION NUMBER : LTW - 6210 - 0142 - P01
PROJECT or W.O
DISCIPLINE CODE SEQUENCE NO DATE PAGE NO
NO
1000500 PI 0142_A 09 / 03 / 2009
5. BASIS / METHODOLOGY :-
Referring to "Dynamic Analysis of Water Hammer Loads" of Version 5.00 CAESAR II Application guide
The magnitude of surge loads and its duration, when the pump drops offline due to supply trip shall be
calculated by below methodology.
The magnitude of pressure surge wave, when the pump drops offline due to supply trip can be
estimated from
Equation 1:-
Where, dp = the pressure rise due to the pump’s “instantaneous” stopping
ρ = Fluid density
c = Speed of sound in the fluid
dv = the change in velocity of the fluid
The speed of sound in the fluid can be estimated from
Equation 2:-
Where, Ef = Bulk modulus of the fluid
E = Modulus of elasticity of the pipe
d = Pipe mean diameter
t = Pipe wall thickness
The unbalanced load on the piping system due to the time it takes the pressure wave to pass through
successive elbow-elbow pairs, can be calculated from
Equation 3:-
Where, F unbalanced = The magnitude of this unbalanced load due to pressure surge
The duration of the unbalanced load is found from
Equation 4:-
Where, t duration = The duration of unbalanced load
L = The length of pipe between adjacent elbow-elbow pairs
Slowing the mechanism that tends to reduce the flow rate can reduce the magnitude of the water
hammer loads. In the case of valve closing, this means slowly closing the valve. In the case of a pump
going off line, this means slowly removing power from the pump.
Slowly in each of these instances can be estimated from
Equation 5:-
Where, T = Maximum Time of one wave cycle sec.
If the pump or valve stops in a time shorter than T then the water hammer should be analyzed.
REF. CALCULATION NUMBER : LTW - 6210 - 0142 - P01
PROJECT or W.O
DISCIPLINE CODE SEQUENCE NO DATE PAGE NO
NO
1000500 PI 0142_A 09 / 03 / 2009
6. CONFIRMATION REQUIRED :-
6.1 1ST CONFIRMATION ITEM :- Not applicable
7. COMPUTER CODE IDENTIFICATION :- Not applicable
8. CALCULATION :-
Calculation of velocity of fluid
V = Q DESIGN / Area of flow
V = ( 25000 / 3600 ) / 2.915 = 2.383 m/sec
The max change in velocity of the fluid ( dv ) = 2.383 m/sec
The speed of sound in the fluid can be estimated from
Equation 2:-
From above equation results for calculation of speed of sound in fluid for various diameters
& thickness are tabulated as follows
D (NPS) = 80 56 48 40 32
t (m) = 0.105 0.0417 0.0313 0.0266 0.0234
C (m/sec) = 878.8 713.7 676.8 682.2 708.6
From above table, maximum value of Speed of sound in the fluid 'C' is 879 m/sec
The magnitude of pressure surge wave & the unbalanced load on the piping system,
when the pump drops offline due to supply trip can be estimated from
Equation 1:-
dp = 1000 X 879 X 2.383 = 213523 Kg / m2
Equation 3:-
F unbalanced = 213523 x 2.915 = 622420 Kg
The duration of the unbalanced load is found from
Equation 4:-
From above equation, the duration of the unbalanced load for different elbow-elbow pairs
are tabulated as follows
Elbow pairs = A-B B-C C-D D-E E-F F-G
L (m) = 31.8 28.7 11.1 7.8 14.4 48
t duration (sec)= 0.037 0.033 0.013 0.009 0.017 0.055
REF. CALCULATION NUMBER : LTW - 6210 - 0142 - P01
PROJECT or W.O
DISCIPLINE CODE SEQUENCE NO DATE PAGE NO
NO
1000500 PI 0142_A 09 / 03 / 2009
The smallest time that must be used to close a valve or to bring the pump flowrate to halt, such that
water hammer type pressure pulses are not generated can be found from
Equation 5:-
L = Overall length of piping system
T = ( 2 X 141.8 ) / 879 = 0.323 sec
If the pump / valve stops in a time shorter than calculated T ( 0.323 sec ), then the
water hammer loads become significant & need to be considered as occasional loads in the
piping analysis.
9. RESULT & CONCLUSION :-
The magnitude of the water hammer pressure surge load acting on piping system & its duration
on different elbow-elbow pairs / segments, when the pump drops offline due to supply trip has been
summarized as below
The magnitude of pressure surge wave 213523 Kg / m2
The unbalanced load due to pressure surge on the piping system 622420 Kg
The duration of the unbalanced load on different elbow-elbow pairs / segmenmts
Elbow pairs = A-B B-C C-D D-E E-F F-G
t duration (sec)= 0.037 0.033 0.013 0.009 0.017 0.055
The smallest time that must be used to close a valve or to bring the pump flowrate to halt, such that
water hammer type pressure pulses are not generated (Tmax) is 0.323 sec
