Disclosed herein is a bellow for use in a ball valve, the bellow comprising: a metallic seat at an end of the bellow for providing a contact surface with a ball of a ball valve; and a metallic body integral with the seat; wherein the metallic body has a longitudinally elastic property such that, when the bellow is in use in a ball valve and the bellow is arranged within the housing of the ball valve so that it is always under longitudinal compression, substantially only the compression in the bellow causes the seat to apply a sealing force against the ball of the ball valve that maintains a mechanical seal between the seat and the ball valve. Advantageously, embodiments allow a new design of ball valve that maintains a high standard of performance in subsea environments over long time periods.

A metal bellows for downhole use includes: a bellows capsule with a first end and a second end; an inner diameter side and an outer diameter side arranged between the first end and the second end; where the bellows capsule comprises a first bellows convolution and second bellows convolution and optionally additional bellows convolutions; and each bellows convolution comprises: a root on the inner diameter side of the bellows capsule; a first sidewall extending from the root toward the outer diameter side of the bellows capsule with a first connection point at the distal end; a second sidewall extending from the root toward the outer diameter side of the bellows capsule with a second connection point at the distal end and wherein the second sidewall is on the opposite side of the root as the first sidewall; wherein: the bellows convolutions are formed as a single piece; and the second sidewall connection point of the first bellows convolution is permanently affixed to the first sidewall connection point of the second bellows convolution.

Separator and hydraulic accumulator having such a separator. A separator, in particular for a hydraulic accumulator, such as a bellows accumulator, which is produced by a 3D printing process, consisting of one single diaphragm, which, when viewed in cross section, is deflected in an arcuate shape to form a multitude of bellows pleats at deflection points, which delimit the bellows pleats on the outside and the inside, and in that, to obtain an isotensoid or essentially isotensoid stress profile in the diaphragm, the notional extensions of the diaphragm surfaces adjacent to each deflection point form an acute angle with each other, at least in an initial state.

The present disclosure relates to a bellows seal arrangement having a bellows designed with a controlled shift in effective mean diameter when the bellows is exposed to a pre-determined pressure.