Fancy spending two months on the inside of a large cast iron Victorian gasometer?

That’s just what maintenance experts employed by Historic Scotland are doing to ensure an important piece of the nation’s industrial history is kept in good shape for the future.

The Biggar Gasworks, now a museum, date back to the mid-19th century and the days when coal was used to produce natural gas for towns across Scotland.

An internal inspection of one of the 6m-tall gas storage containers showed the time had come for a substantial programme of work to remove rust and apply special protective paint to inhibit future corrosion.

Ian Lambie, Historic Scotland district architect, said: “Gasworks like the one at Biggar were once a familiar sight in small towns across Scotland but this is the last of its kind.

“It is a great visitor attraction and we are doing all we can to look after it for future generations.

“This maintenance project is quite a major one, and has involved a lot of planning and preparation.

Historic Scotland has employed specialist contractors to carry out some of the work involved.

Before it can begin, five metres of water will have to be pumped out of the containers.

Tests are also being carried out to ensure that sludge is not contaminated with chemical by-products from the gas-making process.

The sludge is being disposed of by a specialist waste-handling company.

Archaeologists will record any newly-exposed parts of the gasometer’s structure.

Similar work is planned on the gasworks’ other container, which dates from just before the First World War, in around two years time.

How the gasometer operated

While the gas produced by coal-fired works contained many noxious substances, such as arsenic, some of the technology made smart use of renewables.

The gasometers were constructed in two parts; a base and a rising cylindrical container which was on castors.

The gas was bubbled into the base of the container through several metres of water.

As the amount of gas increased the container gradually rose to make room for the extra capacity.

The 5mm thick iron and steel rising vessel was, however, very heavy and kept the gas under constant pressure.

This use of gravity meant the gas was forced out into the local grid and would be under enough pressure to provide an effective flame in people’s homes.

Rainwater was also recycled to make sure that the pool in the base of the container remained naturally topped up.

The maintenance project

• In addition to rust removal and painting, Historic Scotland will also be introducing a cathodic protection system inside the container later this year. This will involve attaching zinc bars to the walls. The idea is that the ions which cause metal to corrode are more attracted to zinc than to iron. As a result they will attack the zinc bars rather than affecting the historic iron structure of the gasometer.
  
  
• The gasometer will be completely scaffolded and weather clad for the duration of the operation. The inside will also be heated to avoid humidity problems that can affect the maintenance work.
  
  
• The unusual nature of the working environment means that it will need to be fully scaffolded and artificially lit on the inside.

Biggar Gasworks Museum is in Gas Works Road, Biggar, off the A702. Telephone 01899 221050. Open to the public during the summer only.

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