4,500 tonne UK ammonia plant dismantled for reassembly overseas16 June 2010

Following completion of plant decommissioning at GrowHow UK's Severnside site last November, work has now begun on dismantling and packaging of two LCA (leading concept ammonia) plants and a utilities area, bought by Sigma for resale.

The project to date has consumed more than 60,000 man-hours, under the guidance of project management consultant and CDM (construction, design, management) coordinator RVA Group, working for GrowHow and American assets company Sigma Investment Holdings.

Following two months of RVA planning, specialist dismantling contractor EDS has been appointed by Sigma to begin the process of coding, extracting and preserving every single vessel and associated pipework for export.

Work on site is due to complete in August, when 4,500 tonnes of ammonia production plant will be shipped in 120 containers, 60 enclosed crates, 80 open stillages plus 30 outsize items of deck cargo, all ready for reassembly and return to production.

"It is rare for one consultancy to be appointed for both roles and there are those who might question how we could effectively represent both clients," comments RVA managing director Richard Vann. "Yet in reality it works very well, because it ensures a co-ordinated approach, with common standards and universal protection of interests in a collaborative environment."

Using the original construction designs and drawings, the team has now completed preparation of a methodology and processes for dismantling each component and match-marking it with codes for ease of reconstruction.

"It is fortunate that the drawings are of a high standard, as this gives us a clear indication of the dimensions and weights we are dealing with – up to 116 tonnes," continues Vann.

"The biggest challenge is the logistics of moving people and machinery around such a restricted space. To a large extent we have to work inwards from the periphery, removing components as we go. As we progress through, craneage will then have the access needed to extract some of the more intricate equipment on [its] steelwork skids," he says.

Due to the design of the tank-like PSA vessels, EDS had to design and manufacture a bespoke attachment for the lifting process. Once this shackle is connected to the top lifting point of the tank, the seal to the floor will be cracked and a 450 tonne crawler crane will lift each tank clear in a vertical position.

The hook of a smaller 160 tonne crawler crane will then be attached to the tailing lifting point at the base of the vessels, to enable the tank to be lifted into a horizontal position for transport.

Brian Tinham

Related Companies
RVA Group

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