Kindly refer to the attached excel sheet of a Liquid LPG unloading pipeline at a port. I want to calculate the surge pressure in the described pipeline (58 m) in the emergency scenario when the ROV is shut down.
The required data are also mentioned in the spread sheet. If any other data is required let me know.
There are a couple of methods to calculate the surge pressure that is as under:
P = (0.070) V * L / T
where, P = Pressure rise above static pressure. psi
V = Velocity of the fluid flow, ft/sec
L = Length of the pipe, ft
T = closure time of the valve, sec
P = 0.070 x 9.834 X 190.2887 / 5
= 26.19 psi
= 1.831 kg/cm2
This is for case 1 where the time for valve closure is 5 secs
P = 0.070 X 9.834 X 190.2887 / 10
= 13.095 psi
= 0.915 kg/cm2
This is for case 2 where the time for valve closure is 10 secs
The results second method was provided by my client who gave a different value of surge. This method used the STONER SOFTWARE. In this method the dependency of the surge pressure on the valve closing time is very negligible. The output of the results is as under
Vavle Closing Time Surge Pressure
(mins) (psi) kg/cm2
0.1 310 21.8
0.2 310 21.8
0.3 310 21.8
0.4 310 21.8
0.5 309 21.72
0.6 308 21.65
0.7 307 21.58
0.8 306 21.51
0.9 305 21.44
1 305 21.44
2 298 20.95
3 293 20.6
I am not trying to compare the software with the hand calculations. At least they should be within agreeable range.
Any one has a some other method or guidelines kindly share with me.
Kindly give me your valuable insights and comments.
Waiting eagerly for reply