VIDEO: Masterton Dismantling LNG Tanks in Glen Mavis (UK)

Based on the success of the demolition and dismantling of the LNG Tanks in Manchester, Masterton was awarded the sister plant in Glen Mavis, Scotland. This project involved the dismantling and demolition of two further liquefied natural gas (LNG) tanks and associated process plant.

The demolition of the site involved the removal of all plant, equipment, pipework and tanks on the site which included the Selexol Plant, Liquefaction, Boil Off, Power Generation, and Storage Facilities.

The tanks were each 42m high with a domed roof formed from steel angle framework and held in position by a 40mm thick compression ring that wrapped around the top of each tank. The compression ring covered the top 1.2m section of the tank as well as the bottom 1.2m of the tank roof. The steel outer tanks housed the inner tanks which held the liquefied gas, these tanks were constructed from a mixture of aluminium and nickel steel. The void between the two tanks was insulated using fibreglass and perlite insulation.

The demolition of the tanks involved the pre-weakening of the steel angle framework with 25% of the beams being fully ‘sit cut’ and the remainder all had the web cut. Explosive cutting charges were used to initiate the roof collapse; these had to be strategically placed to enable the roof to collapse directly inside the inner tank. Each of the tank roofs way in excess of 120 tonnes.

A method to pre-weaken the tank and compression ring with a number of stitch cuts was developed – once the tank was sufficiently pre-weakened several 40mm diameter ropes were connected to the top segments of the tank and in turn a large excavator pulled the sections of the tank from outside the bund wall. The weight of the compression ring ensured that the stitch cuts were easily sheared and the section of the tank fell in a controlled manner to the floor for further processing. A super long reach with shear attachment then followed on by cutting the tank down to ground level.

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LNG World News Staff, September 16, 2013; Image: Masterton