Gas cylinder thread?

[Nitpicker]

Anyone know the thread size at the top of a 80# stainless steel inert gas cylinder? Appears to be close to a 1" internal thread (metric?,left hand?). I don't have a thread gauge that fits and no bolt I have matches -- can't find a reference, and local sources haven't helped. I need to locate a semi permanent plug that will be tapped for an eyebolt to hang the cylinder. No brand name on the cylinder. If it matters the stainless is drill sergeant hard and 5/16 thick.

 

[Jim Johnstone]

Any photos or information stamped onto the shoulder of the tank? What is the working pressure, and does it appear to be a straight thread or a tapered thread?

I've never seen a stainless high pressure gas cylinder and would be interested to see one.

 

[A_Pmech]

Probably 3/4 NGT. 3/4 NPT will thread into it.

 

[Jim Johnstone]

Probably 3/4 NGT. 3/4 NPT will thread into it.

Yeah odds are NGT, I'm rather curious about him calling it stainless.

 

[Ironhorse]

View attachment 225139

 

[A_Pmech]

Yeah odds are NGT, I'm rather curious about him calling it stainless.

Stainless ultra high pressure bottles are available, they're usually reserved for scientific gasses though.

I suspect they're rather spendy...

 

[Jim Johnstone]

Stainless ultra high pressure bottles are available, they're usually reserved for scientific gasses though.

I suspect they're rather spendy...

And also overkill for anything anyone would be using at home. I've dealt with enough high pressure gasses, up to 4500 psi for 10 plus years, and have never once seen a stainless cylinder "in the wild" lol

 

[Nitpicker]

Give me until the AM. I'll see what I can do for photos.

 

[Jim Johnstone]

Give me until the AM. I'll see what I can do for photos.

Also, look at the lettering on the shoulder of the tank and give us any information that is stamped there.

 

[Nitpicker]

Sometimes I seem to go out of my way to prove I'm a novice at this. It seems that the tank is not stainless but rather contained a stainless mix of gasses. When I picked it up, the yard guy said that there was a stainless tank for me. When I cut the bottom it went through five bimetal blades. I thought the tank, not the contents was "stainless". Anyway here are some pictures. I'm looking still for a thread gauge so I can locate a plug at the top.

 

[Jim Johnstone]

Definitely an NGT thread, likely 3/4". I would so go buy something from Home Depot or Lowes that has a 3/4" NPT thread on it, something like a pipe plug to test the thread.

Also, was that cylinder condemned? I noticed the markings after ICC were crossed out. That is an oldie, I can see April 1940 as the oldest visible re-certification date, so it's older than that.

 

[WWIIjeep]

Also, was that cylinder condemned? I noticed the markings after ICC were crossed out. That is an oldie, I can see April 1940 as the oldest visible re-certification date, so it's older than that.

Looks like under the X-outs it was a 3A1800 rating, which is now generally only used for Carbon Dioxide. Standard Tri-Mix fills usually exceed 1800 PSIG now, so maybe that's why they removed it from service. Just guessing without being able to see all the shoulder markings.

To the OP: The "Tri-mix" referred to on the label in your 5th photo is a mix of helium, argon and CO2 used for welding stainless steel. It's a blend that has lost favor in more recent years.

 

[Jim Johnstone]

Looks like under the X-outs it was a 3A1800 rating, which is now generally only used for Carbon Dioxide. Standard Tri-Mix fills usually exceed 1800 PSIG now, so maybe that's why they removed it from service. Just guessing without being able to see all the shoulder markings.

To the OP: The "Tri-mix" referred to on the label in your 5th photo is a mix of helium, argon and CO2 used for welding stainless steel. It's a blend that has lost favor in more recent years.

No way they removed it from service for being "only" 1800 psi. My guess is it failed either visual inspection or hydrostatic testing. There are no laws requiring different gasses to have specific pressure ratings of cylinders, they could have filled it with tri-mix, nitrogen, oxygen, helium, argon, or any other compressible gas. All they would have had to do is remove the labels showing what was in it, and replace the valve with the appropriate one for whatever gas was going to be put in it.

 

[Nitpicker]

There is a 1939 date elsewhere.

 

[BD1]

'' I need to locate a semi permanent plug that will be tapped for an eyebolt to hang the cylinder.''
There was another posting similar to this. Guy used a trailer ball welded to the tank and drilled the center of the ball for hanging. Just a thought.

 

[theknurl]

definitely 3/4" NGT......

have seen tanks marked chrome-moly now and then

oldest tank? 1st test date 1909....5 columns of date stamps, an old Linde tank

 

[trackwelder]

Weld a black pipe union in there. maybe 1/2" or such

 

[John Timmins]

I was in a welding supply place when a guy walks in and asks the same question about the threads and do they have a tap. they tell him all the bottles get hydroed and serviscd in Tampa.

look at the guy and it was Smokey Yunick. His "Best Damned Garage in Town " is down the street. I always wondered what Smokey was up to with that bottle project. Hi car was a little beater with hand crank windows and no A.C. He never owned a new car in his life.

Next to the welding shop was Tom Cannon's shop. He once had 4 prepped cars at LeMans one year and did the 24 Hour at Daytona...the first guy to aim headlights criss-crossed to see the walls and track.

Between the two was Fish Carbuerator and Ray Fox's shop - Kiekhaefer's NASCAR engine builder in the '52 - '56 years.....

 

[fourjeepin]

Curious, why are you hanging the cylinder and why did you cut the bottom out? Giant wind chime?

 

[WWIIjeep]

No way they removed it from service for being "only" 1800 psi. My guess is it failed either visual inspection or hydrostatic testing. There are no laws requiring different gasses to have specific pressure ratings of cylinders, they could have filled it with tri-mix, nitrogen, oxygen, helium, argon, or any other compressible gas. All they would have had to do is remove the labels showing what was in it, and replace the valve with the appropriate one for whatever gas was going to be put in it.

It depends on the gas distributor. For 31 years, I worked for a company that owned over 100 welding gas cylinders, and as the shop foreman, with the responsiblity of administering our welding supply contracts, I saw a lot of things happen with the various gas distributors we worked with during that time.

One company in particular--AIRCO (when they were still in the welding gas supply business)--went through a phase where they were refusing to service all high pressure COCs with less than a 2015 PSI service pressure rating. They even rejected one with a 3A2000 stamping (for the lack of 15 lbs). A different gas distributor we subsequently contracted with had no problem allowing us to reinstate that particular (oxygen) cylinder in service after it passed hydrotest. This was during the era when COCs were not necessarily exchanged, but instead were filled and returned to their owner. During that same time, AIRCO also refused to convert carbon dioxide cylinders to any other type of gas service.

I'll agree with you that there are no "laws" requiring different gasses to have specific pressure ratings of cylinders, but that doesn't stop a company from having an internal policy for what they will accept, especially regarding COCs. I'm just saying it's not as "black and white" as you make it sound.

I'll further agree that there are a variety of other generally more common reasons for cylinders to be rejected for refill, or condemned and removed from service.

definitely 3/4" NGT......

have seen tanks marked chrome-moly now and then

Another common marking--especially on WWII vintage cylinders is "shatterproof." Although it's probably a lot less common nowadays than it was when I first started in the welding industry.

oldest tank? 1st test date 1909....5 columns of date stamps, an old Linde tank

1907 is the oldest I can remember seeing, and it was still in service at Y2K.