Cylinder manufacturing

[metalmeltr]

I recently read that welding on cylinders is not alowed even in manufacturing if so how are they made?

[bandsawguy]

I sell blades into a factory that makes various sizes of tanks. mostly I see smaller oxygen tanks there. the smaller ones seem to start out as a flat disk. I know they make large ones there too. maybe next week when I am in I will ask about larger welding tanks.

[whateg0]

There was an episode of 'How It's Made' awhile back that showed them making compressed gas cylinders. It starts out as a flat disk and is pushed through a progressively smaller set of holes by a mandrel until it is the desired size. Then the top is heated and spun down to the neck size. The bottom is dimpled, the top is threaded, and it's done.

Dave

[scribbles]

I saw that episode as well. It was kind of a mix of pressing and forgoing. But it started as a single disk, very cool, and strong.

[greywynd]

To make the shape of the bottle they would either be done by spinning, or using draw dies (Mandrel and a 'hole' which it is forced through). Draw dies are interesting in that they will only go so far each 'press', so it must be done in stages for long cylinders. 'Redraws' to make it longer are generally limited to about three, but it can vary depending on materials and other factors.

[aametalmaster]

Here is how this company does it. Keep clicking the links on the left.

http://www.norriscylinder.com/tech_high.htm

I saw the How Its Made also and learned a few things about them...Bob

[usmcpop]

Thanks, Bob. I've seen pics and descriptions (and that show), just couldn't fine a real site link.

[Roger]

Have have see many high pressure and low pressure welded pressure vessels in many different shapes including one HP vessel shaped like a 10 ft foot ball.

High pressure synthetic filament wound pressure vessels. First saw them as round O2 cylinders on military fighter aircraft. Later fire fighters used filament wound cylinders to supply breathing air. They are much lighter than steel or aluminum cylinders but hydro test can't extend their life. Newer models have longer life than what was made a few years ago.

I have seen shatter proof steel HP cylinders wrapped with steel wire.

I once worked in very high pressure test facility. There we could expose stuff to 60,000psi water pressure. The 60,000 psi pressure vessels were 16 inch naval gun armor piercing projectiles. (no explosives) They were on stands pointy end down with rear fuse replaced with screw in plug that gave access to interior.

[Farmer]

I was the General Foreman at the plant BandSawGuy is speaking of . At the time it was called Steel Cylinder Manufacturing it is now owned by a company called Worthington ( they are from Ohio I believe ).

there were to types of HP cylinders made there . 1 from spun tube and the other done made from a flat disc in a process called DDI ( deep drawn ironed )

The 2 cylinders did the same jobs but have very different physical characteristics .

Spun cylinders tend to be much heavier as the side wall are much thicker and the inside / outside finish are a bit rough . Wall thickness along the length can very by quite a bit . And the Bottom is very thick due to the way it is manufactured .

A DDI cylinder is consideribly lighter , with a very smooth inner and outer wall . I do not remember the specs ( it has been 18 years ) . But Wall thickness was around .110 and .125 depending on cylinder size . The wall thickness did not very by .001 along the entire length of the cylinder . This type of cylinder has many advantages . Very light weight and strong .

Spun cylinders are made from seamless tube . They are cut to a specific length for the size cylinder you are to build . The cut tubes are then put onto a peheating table/roller and 1 end is heated to bright red . It is then picked up and put into a machine we called a spinner . Like a large lathe . It was then hydraulically clamped into place and another torch lit to keep the end red hot . While the cylinder is spinning a hardened metal block was indexed to move toward the metal and swing in a half arch . very similar to how a potter would form a vase on a potting wheel . The block folds the metal toward the center and the table would index a bit closer till the bottom was formed . A 2nd torch is also used to finish closing the bottom when all the metal is folded in . The tube is removed from the spinner and then placed on a bottom press ( while red hot ) and hit . This gives the tube the flat bottom .

The process is then repeated for the top using the same machines , but the set up is a bit different as we need to form the crown / and then a neck for the valve.

The DDI cylinder was then made from a flat disc of 4130 of varying diameters and thicknesses . Each size cylinder needed a different blank size . All the blanks were washed to remove oil and be run through a trim lathe to help stress relieve the metal from the blanking process . Once washed the blanks were run thru a phosphate bath to Lube the metal . From there it is brought to a press .

The blanks are pressed cold thru a set of dies forming a cup . This what we called 1st draw . The cups were then run through an anealling furnace to soften them up as they were work hardened from being formed in the press . After annealing the cups were run thru a shotblasting machine to remove any scale or carbon from annealing .9 ( A very clean surface was needed to ensure a proper coating of phosphate) They were again run thru a phosphate bath and then run thru a different die set and drawn again . The cup was then about 1/2 as big around and twice as long .

Depending on the cylinder to be made the cups could be drawn as many as 4 times .
example -20 cu ft cylinder 2 draws

medical d or e 3 draws ( same cup as 20 cu ft with 1 extra draw )

80 -110 - 125 cu ft 7 inch diameter 3 draws

250 -300 cubic foot 4 draws

When the tubes were finished the interiors are inspected by an independant 3rd party. No scractches or any gouging is allowed as this can cause the cylinder to fail in the field . That would really ruin your day .

the tubes are cut to a specific length and bottom pressed ( dimpled ) . They are sent to be spun . Same a procedure 2 in the tube type cylinder .

From spinning the cylinders are then
heat treated
shot blasted to remove scale from heat treat
machined
hydrostatically tested and assigned a serial number upon passing
roll stamped
neck ring installed
valved
capped
painted to customer specification .

See nothing to it

[bandsawguy]

thats for the further enlightenment Farmer. I sold general line industrial supplies to Steel Cylinder back in the day. I was working for White Supply out of Chatham. Now I am working on getting them to buy the blades we are selling throught the new company we recently started up. I am hoping to be in the plant next week.