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Twinwoods significantly reduces boiler maintenance time and cost with ContraFlex® jackets

The challenge

The biomass boilers used by Twinwoods Heat and Power undergo maintenance works every 12 – 18 months. Downtime for this work needs to be minimised because it impacts profitability.

Any maintenance work is complicated by the insulation on the boilers. Before maintenance work can begin, the insulation and cladding needs to be removed – a time-consuming task that involves a team of several people. This meant that maintenance was taking longer than was acceptable, costing time and money. Further, the insulation was not reusable, so there were additional costs involved in new insulation.

The plant operator approached us to supply a retrofit boiler insulation solution for one of its boilers that was rapid to remove
and reusable.

Our solution 

We proposed ContraFlex® High Temperature Insulation Jackets. The jackets can be used in operating temperatures up to 550°C, which is more than enough for the biomass boilers’ operating temperature of 450°C and provide the same level of protection as the existing insulation.

Our engineers designed a bespoke system for attaching the jackets to the biomass boiler itself. The jackets were manufactured as a series of made-to-measure mats covering the surface area of the boiler. The first two layers were attached via pins welded to the side of the boiler. Steel wire is looped around anchor points on the mats and tightened to minimise the gaps and reduce heat loss.

A final layer was installed to cover the new internal layers and the gap in the cladding. A jacket made of double coated silicone
was attached to the existing cladding using turn buttons. This improves the aesthetics of the design. More importantly, it makes ongoing maintenance more straightforward. In a plant of this type, wood dust and ash are a common issue; with the ContraFlex® system designed for this project, the jackets can simply be wiped clean and will look as-good-as new.

Installation had to happen on a very tight timescale during the plant’s annual shutdown. We carried out several surveys to ensure all measurements and calculations were right first time. We then liaised closely with the plant operator to ensure the jackets were manufactured and installed in the window available to us.


Lee Parnaby, Business Development Manager at ContraFlex®, said: “Removing insulation and cladding can be a long process, on this plant it could take multiple shifts and involve numerous people. In contrast, removing the ContraFlex® jackets will take a team of two people around half a day, and be replaced just as quickly when maintenance is complete. It will save the plant operator a great deal of time and money.”

Kim Hall, Manager at Twinwoods Heat & Power Ltd said: “All works carried out by ContraFlex® have been done in a professional and timely manner. The team followed all our industry permits and our COVID-19 workplace conditions. Their work is of excellent standard and I would be more than happy to recommend them to anyone looking for these types of works. We shall definitely be using them again in the future.”

To find out if ContraFlex® is the right solution for your installation talk to us…

T: +44 (0)1452 880 880