Over-pressure limiting arrangement for a cryogen vessel

An over-pressure limiting arrangement for a cryogen vessel comprising:

• an access neck that provides access into a cryogen vessel at its lower extremity;
• a tubular structure extending through the access neck;
• a turret outer assembly joined to the cryogen vessel in a leak-tight manner and defining an interior volume which is separated from atmosphere by a protective valve or burst disc, the interior volume enclosing upper extremities of the access neck and the tubular structure;
• an egress path defining a route for cryogen gas to escape from the turret outer assembly;
• and
• a pressure limiting device sealing the egress path from the interior of the turret outer assembly, operable to open in response to a differential pressure between the interior of the turret outer assembly and the interior of the egress path exceeding a predetermined value;
• characterized in that the over-pressure limiting arrangement further comprises—an auxiliary burst disc attached to the tubular structure, such that an inner surface of the auxiliary burst disc is exposed to the interior of the tubular structure, and an outer surface of the auxiliary burst disc is exposed to the interior volume of the turret outer assembly.