Masterton dismantles first LNG holders in Europe 16 October 2012

Grangemouth-based decommissioning specialist Masterton is dismantling four liquefied natural gas (LNG) tanks and associated plant at National Grid's Heath Farm Lane storage facility at Partington, Manchester.

The £4m contract sees the first LNG demolition project of its kind in Europe and Masterton project manager Matt Harvey says the firm is using pioneering techniques.

Work commenced on the 195,000m² site with testing and preparation to purge it of residual risks.

Harvey explains that Masterton's team used hot cutting techniques and demolition excavators with shears to remove low level pipework and vessels from the vaporisation and liquefaction plant.

It then turned its attention to the site's four LNG double-skinned gas tanks, which are 45m high and 135m in circumference, and used to store over 21,000 tonnes of LNG at minus 160 degrees.

These are very different in to traditional gas holders, being steel tank-within-a-tank structures with solid sides and steeply sloping arched roofs supported by a series of arch beams. Each roof alone weighs some 150 tonnes.

"The liquefaction process refrigerates the gas at extremely low temperatures and therefore the tanks were designed to effectively act as giant thermos flasks," explains Harvey.

"Dismantling the steep roofs was initially a concern: the safety of our men would have been compromised by working at such heights as the very heavy structure became unstable," he continues.

"However ... we designed a method that would use explosive charges to cut through the outer steel roof and ensure it dropped safely to the ground within the body of the gas holder whilst all our operatives were safely beyond the exclusion zone."

Following rigorous testing, the 60 steel supporting roof beams of the first holder were exposed before being pre-weakened with sit cuts, and 45 explosives charges were inserted. The first tank roof was successfully blasted at 12 noon on 4 October.

Commenting on the explosive demolition, National Grid projects commissioning manager Frank Harries says: "Thanks to the professionalism of everyone in the Masterton team, all went according to plan. Their pioneering approach has been very successful indeed, with the tank roof collapsing in on the structure perfectly.

"We have now established a very safe and effective way of tackling these difficult and unusual structures."

Brian Tinham

Related Companies
Masterton
National Grid Co Plc

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