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I am constructing two oil storage tanks for a customer located in New Zealand. The drawings he sent me are metric, so the first thing I had to do is convert them to 1/4 scale. One tank will be 12-3/4 inches in diameter by 14-3/4 inches high. in 1/4 scale that is 51 feet in diameter by 59 feet high. The other tank is 18 inches in diameter by 18 inches high coming out to 72 feet in diameter by 72 feet high. These will be the larges tanks I have ever constructed. I will use .0.20" thick styrene for the shells bottoms and roofs. I am just starting and you can see the two roofs and bottoms in the pictures. The models will go in a display case. The real tanks were constructed under the supervision of the customer at a Shell Oil facility. These tanks are very tall for petroleum storage. In the US, most large petroleum storage tanks are 40 to 56 feet high.

Alan Graziano

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Last edited by Alan Graziano
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Myles,

I have some additional progress pictures I will post now. I build the large ones just like smaller ones that I have constructed. You will see in this case I had to join four sheets of styrene for this tank. The maximum sheet size I can buy is 12 inches by 36 inches. This tank works out to 18 inches high by 40-1/16 inches in circumference. The two vertical seams will be hidden by vertical fire-foam piping. The horizontal seam will be visible. I sanded it some but I am sure it will be more visible than the scribed plate seams on the tank. The pictures show the four pieces glued together. I had to take the drawing that was in degrees and convert the nozzle and manway locations to inches of circumference. In addition, I had to convert millimeters to inches because the drawings are metric. You can see how I layed the stairway out in the flat. I marked it with a template I made and glued all the stair treads on.

 

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It's brilliant to glue the stairs onto the walls in the flat. I wonder if this makes it a very delicate operation to form the cylinder without knocking off the steps in the process? The alternative, of course, is equally daunting since getting those steps attached and properly oriented is not easy. How many internal formers are you going to use to maintain structural integrity?

How are you reinforcing the seams? I'm finding that just butting the sheets together without any backing isn't very secure, but the backing makes having smooth curves more difficult.

Last edited by Trainman2001

Myles,

There is a backing strip about 1/8 inches wide at the four sheet joints. There will be no internal bracing on this tank. The next tank I am building is 18 inches across. I will have bracing on the roof of that tank to prevent the cone from inverting during shipping. The shell does not require bracing because it is round. If I glued braces on you would see distortions in the styrene at the glue joints.

 

Alan Graziano

Myles,

As you can see in the pictures, I rolled and glued the seam without any horizontal stiffeners. The only horizontal members I use are at the top of the tank in order to provide an area to glue the roof to. On a real tank the top angle is typically a 3" x 3" x 3/8" steel angle rolled to the tank radius. I added a four piece roof support n this tank to prevent the roof from imploding during shipping.

Thank you Joe.

 

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Alan:

Thanks - I keep learning stuff from you.
I built a circle cutting jig for my band saw which will do the cutting but this tool will come in handy to draw the outside arc so I can set up the band saw plus if I need a 'one of' I can use it to cut also. Like Myles I did a google search and found a bunch on Ebay ranging from $30 to $60.

Question - you seem to use box cutters instead of Exacto blades to cut plastic - preference or a reason?

Joe

Mike,

the cone roof is made by cutting a circle of .020" styrene and removing a pie shaped piece in order to form a cone. I use a backing strip of .010" styrene to glue the joint and form the cone. The initial diameter of the circle is larger than the diameter of the tank. Once the piece of pie is removed, the diameter gets reduced to the tank diameter.

i place the stair treads on the tank while it is laying as a flat sheet. I scribe .040" styrene to look like grating and cut the pieces into about 1/4" x 5/8 " rectangles for the stair treads. After the tank shell is pulled together and round, I add .060" square styrene posts to each tread that are 7/8 inches long. Lastly, I glue a strip of 1/16" x .020 " styrene strip to the top of the posts to create the top handrail.

alan graziano

Coach,

the seams are scribed with a boxcutter when the sheet is flat. If you look about 12 inches up on each tank, you will see where I seamedtwo sheets together. Because I had to glue the sheets together with a backing strip the styrene distorted and makes the seam stick out more than the others. I am not happy with this but have to accept it. The vertical splice seams are hidden by vertical pipes going up the side of the tank. In real life, tanks can have distortions at seams from welding and from settlement.

 

alan graziano

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