Nitrogen Leak Test 2

[Systrade25]

Hi All,

I’m looking to calculate the number of single nitrogen cylinders required to carry out a leak detection test on a vessel(volume of 80m3)

The leak test pressure is 92.7bar

Nitrogen cylinder -> 7m3 / 2175.5psi

I’m struggling with the fact the bottles will begin to equalize with the test segment meaning it’s not as simple as I first thought. I believe I need to calculate how much gas is in a cylinder between the delivery and test pressure (useable volume)

Any help would be appreciated.

Many Thanks

 

[LittleInch]

A lot is the answer.

The 7m3 is the gas volume at atmospheric pressure.

Start a spread sheet and work it out for each cylinder because as you say, each one will gradually put less and less has into your rather large vessel until you only use about a third of the gas volume.

Why such small cylinders at 150 bar?

What you really need is a nitrogen truck and a compressor. Don't bother with bottles, you will need hundreds to pressurise 80m3 to 93 barg

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Systrade25]

Many Thanks for the reply.
I’ve put the figures into a spreadsheet and the result is showing around 1660 bottles.

I also thought as a quick calc the below could be used:

Bottle
247 SCF * 14.7psia / 2190psia = 1.7ft3

Volume (80m3 or 2825.2 ft3)
2825.2 / 1.7 = 1661 bottles/cylinders

Now where’s that truck!

 

[LittleInch]

As a volume yes, but only if you can extract ALL the gas out of your nitrogen bottles. Without a compressor you can't.

But in pure volume you should divide by (93.7 * 14.51).

But bottles are clearly not practical....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[1503-44]

I suppose it is impossible to hydrotest.

https://www.mtm-inc.com/ap-20150827-asme-code-section-viii-pressure-tests.html

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