The advantages of glass-reinforced plastic (GRP) vessels have been well known to the process sector for decades. However, even in the economic slowdown, investment in them remains robust. For example Forbes, a UK manufacturer of GRP tanks and vessels, has just invested £500000 in the first phase of a brand new manufacturing facility at its site in Kelso, Scotland. A second investment of the same size is also underway.
This latest facility incorporates specialised buildings to handle tanks and vessels up to 14 metres in height with diameters up to five metres, depending on transportation restrictions, with capacities of up to 200m3. One of the main assembly buildings represents a major landmark in Kelso being 18 metres high incorporating 10 tonnes capacity overhead cranes.
This development will also enhance the facilities for the existing thermoplastic tank production shops. The specialised self-contained buildings ensure there is no cross-contamination from other raw materials. Forbes manufactures thermoplastic tanks with capacities from 50 litres to in excess of 50000 litres.
Part of the development will link the GRP winding shops to the new shops. The production of GRP tanks and scrubber shells with or without a thermoplastic inner shell is fully automated in order to keep costs to a minimum and guarantee quality. The extended finishing facility will not only allow more efficient working but will also improve delivery times.
Automation of composite tank production was introduced to the site in the early 1980s with automatic hoop chop winding processes imported from the America. This process has been further developed by the company over the past 25 years, which enables Forbes to produce a number of large tank shells in a day.
"The main limiting factor on output of large diameter tanks is the fitting out. This latest development will solve this problem," stated Kevin Johnston, director in charge of the Kelso factories. "This will allow our five winding mandrels to produce tanks simultaneously."
Standard winding mandrels from two metres diameter to 4.1 metres in diameter permit a large range of tank and tower shells to be produced within hours.
Director Melvyn Jupp states that this new facility will further increase operational efficiency. "The company's set-up is such that we can effectively handle orders worth from just a few hundred Pounds up to large six-figure contracts. Over the past few years we have seen a huge growth in the demand for our quality products. Our sales team has been frustrated at times with our prices being the most competitive but we have been unable to meet the delivery requirements of the customer - meaning lost orders. This new facility will alleviate this delivery problem," he added.
Despite the current downturn in industry in the UK and the rest of the world, Forbes remains optimistic. "Versatility is the key. Being able to offer products made in a variety of plastics materials, to strict quality standards, has won us many orders," concluded Jupp.
Meanwhile in Spelle, Germany, Emsland Flour Mills has highlighted why GRP solutions are winning supporters in many different process sectors. With a history of over a century this milling company nowadays shows very healthy growth in Germany and Central Europe. Emsland Flour Mills produces its own leading brands such as Maxiback.
To meet increasing demands, the storage capacity at the mill in Spelle needed to be expanded. At the time the concrete sub-structure was originally built, it was designed with spare space for a future extension. So the project's main challenges were: to realise as much storage capacity as possible on the available spare space on the sub-structure; design and anchor the new silos to resist the wind loads at a height of up to 36m; and, because the new silos are placed outdoors, to prevent condensation and so maintain the high quality of the Emsland flours.
The company's solution was five glass-reinforced plastic (GRP) flour silos from Polem. The leading Dutch supplier of GRP silos and tanks since the early 1970s, Polem, uses the spray winding manufacturing process. Here, resin and glass fibres are sprayed onto a steel mould which can have a volume up to a maximum of 500m3.
Polem found that that five round silos each with a 2.8m diameter fitted the sub-structure exactly. With each cylinder being 22m high, the overall storage capacity achieved was 700m3.
However, the wind loads on these high silos proved to be three times higher than usual, leaving Polem's engineers with the challenge of getting strong enough anchorage to the concrete sub-structure. As a result, the lower silo section and the steel anchor ring were specially designed to cope with the extremely high loads. The very long silo cylinders were manufactured as one piece for optimal strength.
