Live Top-ups

Cryogenic tanks are generally double-skinned tanks with the intermediate space filled with Perlite as the insulation material. During construction of these tanks the Perlite is normally expanded from ore on site utilising a mobile containerised furnace, then transferred
into the tank pneumatically.

However, over the service life of these tanks, they experience the formation of voids as the Perlite compresses, which results in the appearance of cold spots on the outside
surface of the tank.

PMS Ltd have the equipment and the experience to inject fresh Perlite into the tank to fill up the voids to eliminate these cold spots. Liquified gas storage tanks have to be topped up live using special injection pots, and the transfer of Perlite is effected utilising pressurised Nitrogen. This ensures that there is no addition of Oxygen to the atmosphere inside the intermediate space which normally has a high content of flammable gases.

This operation is carried out under strictly controlled procedures which have been developed and successfully followed on a variety of LNG tanks within the UK. Due to the specially designed lance attachment assembly, the injection lance can be connected to the top up nozzle on the top of the tank without any loss of containment. This procedure has undergone close scrutiny at sites such as Glenmavis and Isle of Grain. In all cases “ZERO EMISSIONS” was maintained.

By moving around the top-up nozzles, it is possible to inject the Perlite under pressure, controlling the direction of the jet to ensure that the space between each nozzle is refilled.

Our experienced engineers are able to meet with clients and explain in detail the technical aspects and engineering requirements of this specialist service.