Abstract: A pressure vessel (1) is described comprising an inner fibre-wound pressure vessel (5), a jacket (3), a lid (17) and a wheel base (9). The wheel base (9) comprises a main body (11) having an open end for receiving the base of the jacket (3); a releasable catch (85) operable to attach the main body (11) of the wheel base (9) to a casing (3) mounted on the main body (11) of the wheel base (9) when the base (76) of jacket (3) is inserted into the open end of the wheel base (9); and wheels rotatably (13) attached to the main body (11) of the wheel base (9). When the jacket (3) is mounted to the wheel base (9), the casing (5) and the wheel base (9) are operable to be transferred between locations using the lid (17) and the wheels (13).