would this work?

i have very limited room to keep my air tanks under the bed. a 3 gallon is just a little too long so i was wondering if i could cut a section out of it an bevel the edges and weld it back together and still be able to put the same pressure in it or is that not such a good idea. by the time i cut it, it would probly become a 2 maybe 2 and a half gallon tank ..... run two and ill have 5 gallons and ill be fine but will it work out safely?