Abstract: A pressure vessel 11 has a hollow member 10, an end closure 19 in telescope relationship with the hollow member, a flexible continuous element 26 extending around the end closure and operatively connecting the closure and the hollow member, a passage 14 for insertion and withdrawal of the continuous element, a removable plug 18 closing said passage for resisting removal of the continuous element, and annular seals 24, 25 between the hollow member and the end closure on both sides of the continuous element. The continuous element may be a length of wire spring.