Queensland Alumina Limited (QAL) is one of the largest alumina refineries of Alumina production capacity in the world, located in Gladstone, Queensland.
Operating since 1967, the refinery has a capacity to produce 3.95 million tonnes of the world’s best smelter grade alumina per year. The refinery covers 80 hectares of a 3,050 hectare site on the south-east outskirts of the city of Gladstone. Adjacent to the plant is a wharf and storage facility on South Trees Island, which is connected to the mainland by a causeway bridge.
The refinery hosts boilers, cooling towers, electrical substations, vessels and pipe racks, all requiring insulation and in some cases, asbestos removal. McMahon Services entered a three year Maintenance Contract in January 2012 to manage and systematically remove friable asbestos lagging from over 20km of pipes and boilers on-site. A permanent base was established within the plant and a team of 25 asbestos technicians was recruited locally. The contract has recently been extended for a further two years, and will now finish in December 2017.
In addition to asbestos removal, the team comprises of carpenters to build asbestos removal enclosures, scaffolders to provide safe access to plant, insulation installers (laggers) and sheet metal workers to re-clad the working plant. Plant conditions are hot and relatively hostile requiring the utmost care, preparation and planning employing world’s best practice techniques to execute a program that progresses in tandem within a fully operational plant.
When QAL was constructed in the early 1960’s, pipe work was lined with asbestos. At the time, it was the best form of insulation for pipe work running at high temperatures and pressures. Now pipes are lagged with pre-moulded ‘Rook Wool’ insulation.
A large part of the overall contract involves McMahon Services stripping asbestos and re-lagging sections of pipe work. Some pipes running at pressure of 5000kPa and 390 degrees and the others pipe running, slightly cooler, at 190 degrees and 500kPa.
Working with asbestos as well as hot pipes requires extra precaution to be taken. Asbestos work enclosures have to be fully sealed and operate under negative pressure. Negative air units draw air flow at a minimum of 12Pa (pascal), ensuring that the temperature within the enclosure is reduced. These ‘neg-air’ units maintain a minimum of six air changes per hour and fitted with High Efficiency Particulate Air (HEPA) filters and internal pre filters.
Another measure to eliminate heat stress involves crews wearing specially designed under-garments. This garment is worn close to the body and contains tubes continually circulating with cool water, helping maintain body temperature. Over that garment they wear a disposable ‘Tyvex’ suit and then an ‘aluminised furnace’ suit on top of the other two. Crews also breathe chilled air that is fed via an airline respirator.
In addition to this, air-conditioning is specially ducted into the structure, and workers can only spend a limited amount of time within the work enclosure to eliminate heat stress.
To safely remove the asbestos, it is dampened and carefully bagged, moved into another section of the enclosure where the external surface of the bag is wet wiped, then double bagged and placed in a secure area for safe disposal.
QAL have their own Hygiene Department on site, which oversees all of the asbestos
removal. Due to their growing confidence in McMahon Services, the Hygiene Department now allow us to incorporate larger encapsulations into our removal processes. Allowing us to construct larger removal areas, it has dramatically cut down the asbestos removal time, resulting in valuable efficiencies gained for the client.
