Patent ID: 8623267

Claim:
A method of making a pressure vessel comprising the steps of: a) providing a mold featuring walls defining a generally tubular center section and two generally rounded end portions located one each at opposing longitudinal ends of the center section, said mold walls also defining a foot portion in communication with a first one of the rounded end portions of the mold, said foot portion having a head portion and a neck portion with the neck portion extending between the head portion and the first one of the rounded end portions of the mold, said neck portion of the mold being dimensionally narrower than the head portion of the mold; b) inserting a material into the mold; c) blowing pressurized gas into the center of the material so that the material expands to the walls of the mold so that a pressure vessel is formed; d) restricting the flow of air into the foot portion of the mold using the neck portion of the mold so that migration of material out of the foot portion of the mold is restricted so that the material entirely fills the foot portion of the mold so that the foot portion of the mold forms a closed end of the vessel.