I remember the screaming I got during my IDC when the course twit went tattling that I was filling to 4000....
SOP for filling AL80's was 2000psi off the banks and top off to 3300psi, riding the compressor (8cfm into 4 tanks = pretty vanilla) and let 'em sit to cool to 3000psi.
Well I made the mistake of extrapolating that over to the steels; the shop owner screamed before looking: I had 3 x 120's filled to 3800 hot....I can only imagine the 'carnage' if I had hit 4000....
But seriously, tanks are the singularly most robust piece of kit we have. When used correctly they are pretty tough. Yes, certain neglects and injuries will kill them as surely as a missile against a WWII battle tank, but a little overpressure once in a while will not compromise them. "A little" however is the quibbling point. I am not adverse to putting the hot pressure up by <=10% while filling: it cools to spec and cuts the work load filling in half, saving the time of re-whipping to top up cooled tanks. I am sure that there are many people who will scream "no!!!!" but in all the shops I have worked at, that has always (except for 1) been normal practice.
In one liveabord operation (that was the exception) the SOP included SLAMMING 3800psi hot into AL80's just as fast as the 1/4" ss tubing would deliver it the 6 whip manifolds. Up to 5x a day, routinely pushing the limits like that (3400-3500psi cold) is silly and asking for grief. Yes we did manage to get about 90cuft out of Al80's but was the cost worth it?? I did not see the threads when it was time to replace tanks (they sold them instead of hydro testing-- I wonder why??) but I doubt they were pretty. I am pretty sure that the life expectancy of tanks hit like that for 5 years is going to be significantly reduced (IMHO)
So OP, if you are looking to get bigger volumes, there are much safer ways to achieve your goal of taking half of earth's atmosphere down with you. I for one would not want to be playing with fire pushing those tanks like that.
take a look at How much energy is there in a filled scuba tank
using that site's mathematically derived formula for energy contained in scuba tanks:
E = P0*V0*450
E = 275bar*18liter*450
E = 2 227 500 joule
now if that energy is released catastrophically... its equivalent to roughly 542g of TNT,
think of how a hand grenade is made: approximately 150g TNT inside a half a kilogram of steel....
here we have 542g of TNT and 10Kg of steel....
Still want to over fill???
SOP for filling AL80's was 2000psi off the banks and top off to 3300psi, riding the compressor (8cfm into 4 tanks = pretty vanilla) and let 'em sit to cool to 3000psi.
Well I made the mistake of extrapolating that over to the steels; the shop owner screamed before looking: I had 3 x 120's filled to 3800 hot....I can only imagine the 'carnage' if I had hit 4000....
But seriously, tanks are the singularly most robust piece of kit we have. When used correctly they are pretty tough. Yes, certain neglects and injuries will kill them as surely as a missile against a WWII battle tank, but a little overpressure once in a while will not compromise them. "A little" however is the quibbling point. I am not adverse to putting the hot pressure up by <=10% while filling: it cools to spec and cuts the work load filling in half, saving the time of re-whipping to top up cooled tanks. I am sure that there are many people who will scream "no!!!!" but in all the shops I have worked at, that has always (except for 1) been normal practice.
In one liveabord operation (that was the exception) the SOP included SLAMMING 3800psi hot into AL80's just as fast as the 1/4" ss tubing would deliver it the 6 whip manifolds. Up to 5x a day, routinely pushing the limits like that (3400-3500psi cold) is silly and asking for grief. Yes we did manage to get about 90cuft out of Al80's but was the cost worth it?? I did not see the threads when it was time to replace tanks (they sold them instead of hydro testing-- I wonder why??) but I doubt they were pretty. I am pretty sure that the life expectancy of tanks hit like that for 5 years is going to be significantly reduced (IMHO)
So OP, if you are looking to get bigger volumes, there are much safer ways to achieve your goal of taking half of earth's atmosphere down with you. I for one would not want to be playing with fire pushing those tanks like that.
take a look at How much energy is there in a filled scuba tank
using that site's mathematically derived formula for energy contained in scuba tanks:
E = P0*V0*450
E = 275bar*18liter*450
E = 2 227 500 joule
now if that energy is released catastrophically... its equivalent to roughly 542g of TNT,
think of how a hand grenade is made: approximately 150g TNT inside a half a kilogram of steel....
here we have 542g of TNT and 10Kg of steel....
Still want to over fill???
or 
