151M HIGH CONCRETE CHIMNEY WORKS UK OIL REFINERY
In 1989 Rafferty Steeplejacks carried out an inspection of the 3 No. brick liners within the 151.3m high HPBH concrete chimney. The inspection revealed that the brick liners were found to be in a structurally poor and unsafe condition and a substantial demolition, engineering and construction project was therefore required. The 3 No. brick liners had to be demolished piecemeal and replaced with new steel liners throughout the full height of the chimney internally. Such was the faith in Rafferty’s construction and engineering capabilities, the client awarded the £1.65 million contract on single tender. All elements of this contract from piecemeal demolition of the original brick liners to the manufacture and installation of the new steel liners was solely carried out by Rafferty’s, offering the client a full turnkey project from start to finish.
Rafferty’s have been involved in every major shutdown on this oil refinery since 1974. In 2009/2010 we were contracted by the client to carry out detailed inspection and maintenance works on the 3 No. steel liners within the 151.3m high HPBH concrete chimney during the 2010 planned shutdown period.
Health & Safety is always the first consideration of every contract undertaken by Rafferty’s. Careful planning and documented method statements and risk assessments were issued to cover all aspects for the safe execution of this contract. To gain safe access to within the concrete chimney windshield there are a series of internal floors and at the top floor level a series of winch arrangements were specifically designed, tested and installed within the chimney windshield. One winch was used to hoist all plant and materials and the other winch was used to hoist our operatives to the top floor level of the chimney windshield. Please see the following photographs below showing the winch lifting arrangement.
Once access was achieved, the inspection works could then begin. Within the concrete chimney windshield at the top floor level, scaffolding was erected and fully boarded out to enable the insulation and cladding to be removed from the steel liners at required locations. A thorough inspection of the liner steelwork could then be carried out. Above the roof of the concrete chimney windshield at 151.3m above ground level, the internal liners protrude for a further 3.7m. The liners above roof level were originally constructed from 316 stainless steel and are wrapped with mineral wool insulation and cladding. A thorough inspection of the liners above roof level was necessary and required the removal of the insulation and cladding throughout the full height of each liner. In order to achieve safe access to the full height and 9.1m circumference of the liners above roof level, a specialised multi lift scaffolding arrangement was specifically designed for this demanding task. Once the scaffold access was in position, the cladding and insulation was removed and a thorough inspection of the liner steelwork was carried out. At the levels inspected the liners were found to be in a poor condition with large areas of metal reduction and perforated steelwork evident. Due to time constraints the replacement of the liner sections was not possible and therefore structrual over-plating works was determined as the only viable option for a suitable repair.
The aforementioned project was successfully completed within the required shutdown period, without any safety incidents and to the complete satisfaction of the client. Please see the following photographs which detail the inspection, defects and repairs carried out the liners above roof level.