Pressure vessel and method of manufacture thereof

A method of forming a vessel, having a longitudinal central axis from a cylindrical body and a closure member, said cylindrical body having an annular wall and an open end portion having an enlarged diameter, said closure member having an annular flange and a circumferential groove in an outer wall of said closure member, said method comprising the steps of:

• positioning said closure member in said enlarged diameter open end portion of said cylindrical body with said annular flange of said closure member positioned near said annular wall of said cylindrical body;
• rolling inwardly an annular portion of said annular wall of said cylindrical body into said circumferential groove in said outer wall of said closure member to lock said closure member and said cylindrical body to one another;
• providing a tool having a groove, said groove of said tool engaging said annular flange of said closure member and said open end portion of said cylindrical body;
• and
• causing rapid relative rotation between said tool and said cylindrical body while said tool engages said open end portion of said cylindrical body and said annular flange of said closure member to produce sufficient heat to fuse said annular flange of said closure member to said open end portion of said cylindrical body.