Sciencemadness Discussion Board

Pressure vessel safety

Hazards79 - 23-8-2019 at 10:26

Hi Members.

I'm hoping for some answers for building a safe pressure vessel that a friend has asked me to have a go at. Now I have done a fair amount of research and come across all sorts of formulas that I'm sure have me close to an answer but this comes down to personal safety and I'm a welder not a chemist so I was directed to ask my question here on your site as I'm told it's my best hope.

Now I've been asked to create a 10 litre stainless steel pressure vessel that my friend wants to put 1kg of I2 with 1 litre of H3PO2 and seal it up which creates HI.

Now I was told this reaction is exothermic and can be volatile so I need to know how to calculate the pressure and temperature that will be created inside the vessel so I know the gauge of material to use to manufacture the vessel and to install the correctly rated pressure relief valve so that there are no catastrophic failures of the vessel.

Any help would be great as your kind of my last hope unless I go to my local uni and ask for help.

[Edited on 23-8-2019 by Hazards79]

Metacelsus - 23-8-2019 at 14:15

Oooh boy.

Your friend sounds like he's making meth. I'd advise against helping him. In any case, the reaction to produce HI shouldn't need to be sealed.

Hazards79 - 23-8-2019 at 16:36

Wouldn’t there be more ingredients required to make meth? I also believe HI is used in a vast amount of chemistry procedures as it’s a very strong reducing agent, so making an informed statement like the one above is very counterproductive.Anyway I’m a welder not a chemist so any help on calculations would be fantastic so as to keep things as safe as possible

unionised - 23-8-2019 at 16:37

Quote: Originally posted by Hazards79  
Hi Members.

I'm hoping for some answers for building a safe pressure vessel that a friend has asked me to have a go at. Now I have done a fair amount of research and come across all sorts of formulas that I'm sure have me close to an answer but this comes down to personal safety and I'm a welder not a chemist so I was directed to ask my question here on your site as I'm told it's my best hope.

Now I've been asked to create a 10 litre stainless steel pressure vessel that my friend wants to put 1kg of I2 with 1 litre of H3PO2 and seal it up which creates HI.

Now I was told this reaction is exothermic and can be volatile so I need to know how to calculate the pressure and temperature that will be created inside the vessel so I know the gauge of material to use to manufacture the vessel and to install the correctly rated pressure relief valve so that there are no catastrophic failures of the vessel.

Any help would be great as your kind of my last hope unless I go to my local uni and ask for help.

[Edited on 23-8-2019 by Hazards79]


"I'm hoping for some answers for building a safe pressure vessel that a friend has asked me to have a go at. "
OK, so that's a big "NO!". Pressure vessel design is best left to those who know what they are doing.

"I've been asked to create a 10 litre stainless steel pressure vessel that my friend wants to put 1kg of I2 "

Halogens f*** stainless steel, so that's a big "NO!"
"I have done a fair amount of research "
Nope.
See above.

Even if I didn't think this was meth cookery, I'd be screaming "No" as loud as I could.


Hazards79 - 23-8-2019 at 17:02

I’m a qualified welder with pressure tickets so construction won’t be an issue. I’m more concerned in knowing the chemistry side of things so I know the range of materials I need to work with. I could quite easily just construct a cylinder with domed ends from 10mm thick stainless and know I covered all bases but that kind of seems a bit overkill and would be expensive. I guess I’m looking for the formula used to work out gas pressures created from reactions in sealed vessels and then I can work the rest my self.

draculic acid69 - 23-8-2019 at 17:59

You don't need to mix I2 + h3po2 under pressure.if you cool the acid and add the iodine slowly all the HI won't boil off.you would need to glass/teflon coat a steel vessel of any sort.building a psi vessel for this is completely unnecessary unless you're actually after HI gas which I don't think you are.the only reason one would want to mix those two ingredients under pressure is because of that stupid 100yr old method of reducing ephedrine in sealed steel vessels.if you are making meth aim a little higher and make something better like 4mar or mdma.meth is just so scungy.aim higher.no pun intended.

[Edited on 24-8-2019 by draculic acid69]

Hazards79 - 23-8-2019 at 22:51

I’ll pass the above information on to my friend, but I just ask what is mdma meth. Do you mean mdma that is produced from ketone or are you meaning something else that is produced from pse some how

unionised - 24-8-2019 at 03:32

Quote: Originally posted by Hazards79  
I could quite easily just construct a cylinder with domed ends from 10mm thick stainless and...

Do you know what wet HI/ I2 does to stainless steel?

That's exactly my point.
Get someone who does know about that sort of thing.

Hazards79 - 24-8-2019 at 08:59

Yes I know exactly what HI/I2 does to stainless steel hence the reason I’m not asking what it does to stainless steel

[Edited on 24-8-2019 by Hazards79]

unionised - 24-8-2019 at 12:27

Why are you seeking to make a mixture of iron, chromium and nickel iodides?

Yttrium2 - 6-9-2019 at 18:29

Something screams I'm not getting the full picture of events in this post.


Nonetheless I feel like chiming in,

I personally fancy the pressurized reactions, I to am interested in what the math is. I'm interested in how they work, as well as closed distillations - btw, I just got a small hand boiler which has been loads of fun to play around and philosophize with-


They have glass vessels for pressurized reactions for cheap

Experiments might be necessary if no data can be collected otherwise :P ....(I forget how it was phrased...)



The more elaborate the better-- it's becoming my new "slogan"

Though, it doesn't hold in every situation hehehe...


Where is your friend getting the H3PO2?

I'm not sure how that's produced and, many many things other than that.

It's been a while since chemistry and after taking generally chemistry 1 I can say that I only got a glimpse of how things could be made. Since then I've forgotten. Forgotten a lot..

SWIM - 6-9-2019 at 19:35

Why does he want to use two hard to get chemicals instead of potassium iodide and phosphoric acid, which make HI at STP, and are easy to get?

A friend of mine made me a ~1 liter stainless pressure vessel years ago.
Seamless tubing with flat ends welded on. Maybe 4 mm thick. I forget the ASTM number on the tubing, but its downstairs somewhere.

The flat ends became somewhat domed after the first use.
The stainless threaded plug is a bear to get loose after a few hours at elevated temps. I wish the collar the plug threads into was hexagonal to make getting the plug loose easier.

Works okay for my purposes, but wasn't trying to make HI in it.
Or chromium iodide either.

Fulmen - 7-9-2019 at 02:07

To answer the initial question: That's not how it's done. Reactions doesn't really "produce temperature and pressure", trying to estimate the pressure from a set of ingredients in a sealed container is challenging and fraught with uncertainties.

Sturge11 - 8-9-2019 at 05:33

You really have quite the adventure to embark on if you are wanting to do the research to determine your selection of alloy that has corrosive resistance vs. Hypophos and the Hiodic acids. I would start your search there, and then make sure you can get the material to weld the alloys, as chromium/molyb/nickel alloys are a bit different than your standard mild or stainless steel. Pair that with, even if you get the metal stuck together you need to make sure that the alloy itself is uniformly welded.

I dont know off hand of the types of alloys you are going to want to be looking for, and definitely not their compositions, but I do know that if you are set on completing this project, and this isn't just some backyard round-bottom-bathtub, be cautious of mentioning hydroiodic acid not in conjunction with the iodide you are trying to produce or the grand idea of the disinfectant company you are going to start.