lganga
Mechanical
- Apr 10, 2011
- 109
We have an API tank appendix F with 300 mm of water column pressure.
Relative density es 1
The tank has a N2 blanketing system, and a pressure vaccum valve set at +300 mm / -60 mm of water with a flame arrestor
The overflow pipe has a seal made of a 6" swan neck (two elbows an a pipe), with an open one inch pipe at the top elbow and a filling 1" nozzle at the bottom.
The distance from the bottom elbow to the upper elbow is 670 mm.
if you consider the seal as the distance between both intrados elbows, then it is almost 300 water mm. (able to seal the N2 pressure)
I have seen evidence that the tank has been pressurized over the design pressure (overflow head H + 300 mm water).The external projection of hte bottom plate is seen concave all around it , except in the anchor bolts sectors
My questions are:
1) If the inlet flow is high (from several inlet pipes), the tank liquid level can go over the overflow 6" bore as it discharge by gravity and that can give a pressure over the design pressure.?.
Blanketing is acting together with the high overflow liquid
2) If the tank has an overflow and the liquid density in that moment, is higher than water, then the seal will be filled with this fluid and that can produce an over pressure in the tank (because of different density between the seal swan neck and the tank fluid)?.The tank is filled with pipes from different sources.
Has anybody seen that problem sometime?.
Regards
Luis
Relative density es 1
The tank has a N2 blanketing system, and a pressure vaccum valve set at +300 mm / -60 mm of water with a flame arrestor
The overflow pipe has a seal made of a 6" swan neck (two elbows an a pipe), with an open one inch pipe at the top elbow and a filling 1" nozzle at the bottom.
The distance from the bottom elbow to the upper elbow is 670 mm.
if you consider the seal as the distance between both intrados elbows, then it is almost 300 water mm. (able to seal the N2 pressure)
I have seen evidence that the tank has been pressurized over the design pressure (overflow head H + 300 mm water).The external projection of hte bottom plate is seen concave all around it , except in the anchor bolts sectors
My questions are:
1) If the inlet flow is high (from several inlet pipes), the tank liquid level can go over the overflow 6" bore as it discharge by gravity and that can give a pressure over the design pressure.?.
Blanketing is acting together with the high overflow liquid
2) If the tank has an overflow and the liquid density in that moment, is higher than water, then the seal will be filled with this fluid and that can produce an over pressure in the tank (because of different density between the seal swan neck and the tank fluid)?.The tank is filled with pipes from different sources.
Has anybody seen that problem sometime?.
Regards
Luis
