Rust in closed tanks

[AusGasMan]

What happens to the pressure inside the tank when the oxygen is used in the rusting process. Are the oxygen atoms replaced or does the internal pressure drop? I would imagine the volume change is significant going from 20% down to 5%.

 

[EdStainless]

1. It is rare to find a tank that is both rigid enough and sealed well enough that this could ever be seen.
2. It would also require de-aerated water, another rarity.

The only systems that I have ever seen that met those two criteria were inert gas purged to keep the water oxygen free.

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Plymouth Tube

 

[AusGasMan]

I am not sure if this is so rare. There are several documented deaths from oxygen depletion in tanks. This is documented in our safety meetings. The level had dropped to 5% in one case. I trying to comprehed what happened onsite recently when we oxy cut off bolts above an open well. Initial gas testing came up negative but after cutting off the temp coverplate and inserting the monitor into the well it showed an explosive atmosphere. We were able to lift part of th cover plate prior to cutting and the test was negative. Probably only good for ligher gases which rise. I thought hydrogen sulphide may be present in an oxygen depleted enviroment to make it explosive and as in the tanks does the enviroment of the well have another gas to replace the oxygen when used in the conversion to rust. Any input would be apprichated as I am asking our company to investigate for our safety.

 

[EdStainless]

Well, active corrosion will generate hydrogen.
Did your test say that there was a flammable gas?
After all with low oxygen it wouldn't be able to burn.

I have seen very low oxygen in closed systems with biological activity, but then it was replaced other gases. Gases such as H2S, CO2, ammonia, and so on.

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Plymouth Tube

 

[AusGasMan]

The monitor read combined explosive gas. It is a Altair 4. Reads O2, CO, H2s and comb/ex. It was after cutting off the coverplate bolts that the monitor was partially inserted into the open well and it went into explosive alarm. The well haed was in a open excavation 3 foot deep.

1. Could the cutting torch have left residule gas as it used LPG and O2 for fuel.

2. Could the atmosphere in the well have had a small amount of combustable gas and with the rust depleting the oxygen level to a explosive range.

3 Could the explosive gas form a pocket and when ths oxygen depleted the pocket came into the explosive range. Meaning will the atoms of explosive gas and remaining oxygen stay in close proxcimity to form an explosion.

I'll have to study basic chemestry again as this has me hooked to find out what happened so we dont blow ourselves up.

 

[berkshire]

An oxy acetlyene or oxy/lpg torch uses a stream of oxygen as its cutting jet,not all of this oxygen is consumed by the metal.
B.E.


The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor