I so much like the copper tanks I've seen I decided to make one after my stock tank developed a leak at the weld for the mounting screw. I have Permatex Epoxy Putty'd all the mounting bolts but as they are prone to fail I thought a new tank was in order.
I went to the recycling yard and found a piece of 3" tubing that had no calcium deposits, looked like a cut-off piece that was not used. Just down the street from there is a plumbing supply and I went to buy two caps. When he told me it was $38 each I about had heart failure. Told him no, thankx. He said he understood. Said the previous week he sold 4 4" copper pipes 20 ft long for $1600...dang. I went back to the salvage yard because I had spotted a piece of 3" with a cap, a short length about 8" going into a 3" x3" X1" T fitting. The 1" fitting perfect for a gas cap. The open end was cut off with a Sawz-All leaving a 3/4" stub sticking out to solder a cap to. With this set-up I just needed 1 more cap. Off to eBay, found a buy-it-now for $25 delivered. Got some silver solder and flux for $10, too.
I have to remove the short piece of pipe. Heating up a 3" copper pipe enough to melt the solder at the same time poses a problem of getting it all heated up enough to take it apart before the solder cools and solidifies. I went on the net and found copper melts at a very high heat, almost 2000F and the solder melts at about 500F, really giving a safety margin of almost 1500F degrees before the copper starts to melt. I'm going to use my BBQ starter chimney to heat the fittings so I can get them apart. Not quite sure how I'm going to hang on to the parts, I have large Channellock pliers but they aren't large enough...I'll think of something