Rupture Set Pressure for API 620 tank
Rupture Set Pressure for API 620 tank
(OP)
HI all,
I run into a problem on rupture disc set pressure for a LIN storage tank.
The design pressure of the LIN storage tank is
P=2 psig
I assumed MAWP (Maximum Allowable Working Pressure) equal to design pressure.
MAWP=2.0 psig
Disc rupture pressure tolerance ?P= ±50 mbar (±0.725 psi)
According to our internal set pressure specification,
Minimum Burst Pressure of the rupture disc
BP(min)=1.1×MAWP=1.1×2.0=2.2 psig (operating rate = 80%)
Maximum Burst Pressure of the rupture disc
BP(max)=BPmin+2?P=2.2+2×0.725=3.65 psig
Disc Set Pressure:
BP(nominal)= BP(min)+?P=2.2+0.725=2.925 psig
However, fabricator and system engineering want to set it to 3.5 psig.
Since I am unfamiliar to API 620 tank, any suggestion and comment to that set pressure will be greatly appreciated.
Thanks in advance, John
I run into a problem on rupture disc set pressure for a LIN storage tank.
The design pressure of the LIN storage tank is
P=2 psig
I assumed MAWP (Maximum Allowable Working Pressure) equal to design pressure.
MAWP=2.0 psig
Disc rupture pressure tolerance ?P= ±50 mbar (±0.725 psi)
According to our internal set pressure specification,
Minimum Burst Pressure of the rupture disc
BP(min)=1.1×MAWP=1.1×2.0=2.2 psig (operating rate = 80%)
Maximum Burst Pressure of the rupture disc
BP(max)=BPmin+2?P=2.2+2×0.725=3.65 psig
Disc Set Pressure:
BP(nominal)= BP(min)+?P=2.2+0.725=2.925 psig
However, fabricator and system engineering want to set it to 3.5 psig.
Since I am unfamiliar to API 620 tank, any suggestion and comment to that set pressure will be greatly appreciated.
Thanks in advance, John





RE: Rupture Set Pressure for API 620 tank
The maximum design pressure for the API 620 tanks is 15 psi, hence the setting of the rupture disc burst pressure at around 3.5 psi is irrelevant to the tank design. Can you be a bit more specific with your query, what seems to be your problem you need help with?
cheers,
gr2vessels
RE: Rupture Set Pressure for API 620 tank
I don't have a copy of the standard at hand at the moment, but you may need to increase the design pressure or lower the operating pressure to obtain an adequate variation for vent or rupture disk operation. You might also check what requirements API-2000 has on vent overpressure, if any.
RE: Rupture Set Pressure for API 620 tank
RE: Rupture Set Pressure for API 620 tank
I am curious....
I have seen and specified rupture discks on small pressure vessels (expecially those with toxic or corrosive contents) but almost never on API 650/620 style tanks.
How big is your tank, what liquid is "LIN" (liquid nitrogen ?)and why are you using a rupture disc instead of a conservation vent ?
-MJC
RE: Rupture Set Pressure for API 620 tank
MJC,
The capacity of the LIN storage tank is 450,000 USWG.
Z Wang