Learning about Propane tanks

Hi, I'm new to blacksmithing, just building the shop for my future house. Thats right the shop is being built first:-)
I have started to research propane tank rules etc. Here is what I have
been told and was wondering how much of it is true. Please correct me and add info and references.
Things with ?? are answers I got which caused more question to pop into my head.
1) Tanks under 40 lbs requre the "new" valve with the triangle shaped handle. This indicated a valve that can limit the amount of propane that can be put into the tank.
2) Tanks that are designed to contain more than 40lbs do not need this valve.
3)Tanks under 40 lbs and over 10 yrs old need to be hydro-tested every 5 years.
4) tanks over 40 lbs only need to be visually inspected. ?? by who?? ?? what are they looking for??
5) Tanks that are label as ASME and not DOT tanks do not require inspection, only up-to-date relief valve. These tanks are often refered to as fork-lift tanks.
Questions I have.
Is there a reference that defines the numbers that are stamped on the neck of most high preasure tanks.
I know the difference between Oxygen and acyldlene tanks, even if I cant spell correctly:-)
How about other high preasure gases like nitrogen, argon or hydrogen. Does each tank have a different code?
Can a tank for say CO2 be switched to argon, or a o2 be switched to hydrogen.
Is it always the rule that non-flamable gases use right hand threads and flamable gases use left handed threads.
Are regulatory specific to the gas. Is there more than just high preasure and low preasure?
I'm sure I will think of more later. Al
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These links may answer a few of your questions or direct you somewhere that will:
http://home.comcast.net/~damouth/Tips/OPD.htm
http://www.npga.org / Gary Brady Austin, TX
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Gary Brady wrote:

Thanks for the links. They help to confirm the info and provided some new data. Al
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<< I have started to research propane tank rules etc. Here is what I have been told and was wondering how much of it is true. Please correct me and add info and references. >>
You start by talking about Propane tanks and as far as I can see most of what you found about them may well be true, but then you start asking questions about other gas tanks. There is a big difference between the Propane tanks and the High Pressure tanks and a difference between the regulations that pertain to the High Pressure tanks. I just wanted to make sure you are clear, that the rules you read for Propane tanks are different from the rules for Oxygen, Nitrogen, etc.
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John213a wrote:

You are right. I should have made two posts. My brain was just thinking of the gases I will need, Both for the forge and for the welding setup. Sorry for the confusion.
I have learned that propane rules seems to be divided around the size of the tank with 40lbs being the dividing line and the orientation of the tank, vertical or horizonal. Verticals are called "dot" tanks and horizonal are called "ASME".
The welding gas tanks seem to be divided into flamable and non-flamable gases. Non-flamables are divided into noble and other shield gases. Argon, nitrogen and helium being noble and CO2 being other. The valves, to some degree, determine what is in the tank. Various combination of right hand left-hand and internal or external threads.
I havent found much on Hydrogen.
The propane "gas" is really a liquid in the tank and the preasure is low, less than 100 lbs, and the regulatories dispense less than 30psi. There seem to be a lot of fix preasure preasure regulatorys but it is not clear what the fixed preasure is and can the valve be used as a poor mans preasure adjustor.
I get most of my stuff at auction and I need to know how to spot good tanks and what tanks can be repurposed. For example, can I buy a nitrogen tank, empty it, paint it the proper color and refill for a Helium tank on my tig.
Can I get a pallet of forklift tanks and use them to run the forge?
I found an interesting site on copper pipe. There is a copper pipe rated for gas but the only difference seems to be that the ends come capped, for cleanliness and it has a green color paint on it.
I dont mind paying extra for quality but I want to know that I'm getting quality and just a marketting scam to charge more for a label. When is the product really different and when is it only the paper work. I know for example, and I forget which plane it is, that the starter motor is the same as the one you can get at NAPA for 1/10 the price but it has the tracking paper work and the lawyer fees attached to the price.
Thanks for you help. Al
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Nitrogen is not a noble gas.

Never ever use copper for acetylene. Copper and acetylene react to form a contact explosive.
Gary
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Gary Coffman wrote:

cool;-) Seriously, I was thinking of copper for propone only. I know I should not have mixed propane posting with welding posting. I'm sort of new to this newsgroup thing and have to learn not to type using stream of consience thinking. I sometime get too many threads going in my head.
Thanks for your help Al

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