The MCBO Blog

Boiler Refurbishment at Twyford Water Works

Twyford Waterworks in Hampshire is an Edwardian pumping station and a site of considerable engineering significance. As one of the most complete heritage boiler houses still in existence, it uniquely features three Babcock & Wilcox wrought-iron front (WIF) water tube boilers and a 1914 Hathorn Davey triple expansion steam pumping engine. In 2009 the Twyford Waterworks Trust (TWT) embarked on an ambitious project to return one of the boilers to steam.

Graham Feldwick, volunteer Project Director of the TWT says that Identifying a company to carry out the rebuilding of the boiler and associated steam plant was not easy: “It was of utmost importance for this project to select a company that could not only carry out a first-class restoration of the boiler and steam plant, but that could work collaboratively and easily with other companies, contractors, and TWT’s own team of volunteers.”

H.A McEwen (Boiler Repairs) Ltd of Cowling, North Yorkshire initially received an enquiry to quote for the restoration of the 1906 Babcock & Wilcox Watertube Boiler in 2009. The scheduled work involved carrying out significant structural repairs to the boiler.

This included complete re-tubing of both the main tube bank and superheater tube bundle, as well as a full overhaul of the boiler valves and fittings, the replacement of rivets, and the manufacture and installation of boilerplant equipment such as a new hotwell tank, blowdown receiver and condensate collection vessel.

Graham Feldwick says McEwen’s were selected because of their overall experience, competence and reputation: “They showed great enthusiasm for our project, and the confidence that they could get the job done whatever was thrown up on the way.

“When carrying out the work for the Development part of the project TWT and McEwen’s quickly established a strong rapport, and TWT found that they could put their full trust in them.”

Following a series of site visits by McEwen’s, and a successful Heritage Lottery bid by the Trust, work to strip the boiler down kicked off in earnest in July 2014. This included removing the 4” diameter boiler tubes, superheater tubes, steam valves and various other fixtures and fittings.

The stripped-down elements were returned to the company’s Farling Top Boilerworks in North Yorkshire, where the labour-intensive task of overhauling the large cast headers and lids and replacing the tubes took place.

Boiler tubes
The boiler tubes returned to Farling Top for refurbishment

Alasdair McEwen, Managing Director of the McEwen’s, recalls this phase of the works: “We studied the boiler carefully before commencing the work on-site, and came up with a plan to bring the main headers back with the tubes still expanded into them.

“This meant each header had eight full-length tubes still in place, which were quite a lump to handle, though enabled us to retain the exact dimensions of each header. A jig was made so that when the removed tubes were replaced with new the overall lengths were exact. On returning to the works with the fully overhauled tube headers they went back without issue.”

Steam valve overhaul accreditation allowed McEwen’s to fully refurbish each of the steam valves and re-certificate them in full compliance with the Trust’s boiler insurance organisation, Zurich.

In mid-2015, all the items were transported back to the Waterworks and work began re-building the boiler.

The first job was to replace a number of failed rivets on the steam drum using traditional hot-riveting techniques. Then the large tube sections were lifted back into position within the boiler house using a combination of lifting equipment and manpower.

Back to the waterworks

Each of the eight main header bundles had been hydraulically tested at the McEwen’s works prior to leaving, which meant that only a small number of the riser tubes had to be expanded in on site. This sped up the replacement of the tube bundles and limited the potential risk of leaking tubes further down the line.

“The replacement of the tubes was a real milestone in the restoration project,” explains McEwen. “You could see the excitement starting to build within the Trust members, and it was a pleasure to be a part of it.”

The boiler successfully passed a hydraulic test in July 2015, witnessed by the boiler insurance company, which paved the way for the final phase of the works to commence.

This involved the replacement of key ancillary boilerplant equipment, such as the installation of the main boiler feed tank and blowdown receiver, along with the fabrication and installation of a new steam distribution header. Additionally, the replacement of the pipework throughout was key to allowing the Trust to operate the whole boilerplant with more ease and control.

Careful planning and discussions took place between Trust members and the team of engineers from McEwen’s about how they wanted the system to operate before the working system was initiated.

On the 23rd August 2017, all parties involved in the project assembled at the works to undertake the final steam test on the boiler; the culmination of many years of planning and many hours of hard graft.

The Twyford Boiler Returns to Steam
The Twyford Boiler Returns to Steam

McEwen admits there were a few nerves on the morning of the steam test: “Myself and my team had invested a lot into the project, we knew what it meant to everyone involved and we just wanted the outcome to be a successful one.”

The boiler passed its steaming test and McEwen says there was a huge sense of achievement at the end of the project: “I just want to thank the TWT for all their assistance, hospitality and support throughout this project and also my team of engineers who showed an amazing amount of skill in delivering this final result.”

Project Director Graham Feldwick echoes that sentiment: “It was a great day when the team from McEwen’s stood with TWT’s team of volunteers celebrating the successful steaming to the satisfaction of the Zurich boiler inspector, paving the way to returning to public steamings in 2018.

“Alasdair and his team can be justifiably proud of this fantastic achievement, which many people thought was not possible. Their enthusiasm for the project has remained undiminished from start to finish.”

The successful completion of the ‘Return to Steam’ marks a major milestone in the restoration of an important industrial engineering site and now offers a rare insight into working Edwardian technology. Visitors to planned “steaming days” will now be able to experience first-hand the Waterworks in operation as it was 100 years ago.

This article first appeared in Vintage Spirit Magazine