Betterect collaborated with FLSmidth on a thickener project which entailed the fabrication of several large diameter dewatering tanks also known as thickeners.
Mining News attended an event to view one of the thickeners at Betterect’s fabrication facility in Krugersdorp. Seeing the thickeners gave a glimpse into the precision and quality involved in the making of each thickener. An important point about the thickeners is that they are locally manufactured in South Africa.
“The successful collaboration with our client FLSmidth, and the supply to the end-client in Southern Africa exemplifies the ‘Team Africa’ concept in action; whereby companies are able, through forming synergistic partnerships, to supply and process massive equipment, to the highest specifications, within record time,” said Nicolette Skjoldhammer, Betterect’s managing director.
She added that as a South African company, Betterect prioritised sourcing steel from within the country wherever possible. She also spoke highly of local artisans saying that they were among the best in the world.
“This alignment with FLSmidth exemplifies Betterect’s ‘Team Africa’ concept whereby, through cooperation, we deliver high-calibre pan-African projects. In this case, these robustly-fabricated thickeners will be deployed in the demanding environment of a mine in Southern Africa, where we are giving the end-client the best possible design and fit for their requirements,” she said.
The tanks were not only completed in a record time – less than half the usual time taken to fabricate thickeners of this size – but to the tightest tolerances and most stringent quality criteria. The perfect alignment went beyond the thickeners themselves, however: it is aptly reflected in how Betterect and FLSmidth align their respective skills and precision engineering capabilities. Such capabilities lead to the production of an end product which is in line with the highest design specifications.
Top technology and quality standards
The thickeners are designed for exact alignment in accordance with the highest quality and design codes for deployment on Southern African mines. According to Skjoldhammer, the thickeners were fabricated at Betterect’s fabrication facility.
“We fabricate according to ISO 3834, which specifies the production control requirements for fusion-welded products globally, whether fabricated on-site or in a facility,” she explained.
Over the last five years, after intense investigation and careful consideration, Betterect has invested significantly into the latest pulse arc welding technology, settling on equipment from Finnish OEM, Kemppi, Skjoldhammer addsed.
“The decision to use the Kemppi range of welding equipment was based on it being one of the best available, with the highest inherent safety factors – as well as being user-friendly for the welders and operators. Pulse arc welding technology is extremely effective in ensuring high-quality welds. The technology reduces defects, porosity, cavities or cracks, lack of penetration or lack of fusion. This results in excellent weld quality, strength and integrity; while significantly reducing welding time/duration. This all combines to improve productivity and ultimately reduces cost for the end-user client,” she elaborates.
“In total, the thickeners comprise several hundred tons of platework and structural steel – a total of more than 60km of welding for the project. The pulse arc welding technology made short work of the welding which would otherwise have been an extremely time-consuming exercise – given the enormous size of the structures.
As a standard, no matter how many or what size, at Betterect, each weld undergoes 100% non-destructive testing (NDT) conducted by a permanent, on-site, third-party. “This entails each weld passing either visual, dye penetrant, magnetic particle, radiographic or ultrasonic testing, where the radiographic testing checks for defects inside the weld, while ultrasonic testing conducts a full volumetric examination of the components,” Skjoldhammer explained. “While it is extremely labour-intensive, the process certifies that every weld and join withstands the harsh environment in which the tanks will be deployed,” she added.
As is standard for all Betterect’s projects, fabrication followed the strictest quality assurance and project management protocols, in accordance with SABS 0157 (ISO 9001:2000) and all SHEQ compliance requirements.
Planning to the tee for a successful project
In light of the COVID-19 pandemic Skjoldhammer explained that fortunately, Betterect were not impacted too much lockdown restrictions due to the pandemic. The team planned very carefully to ensure that they had sufficient steel for the project. “Fortunatley because we planned so far in advance for the project, we were very lucky that all the steel arrived prior to the lockdown,” she added.
“Our close association with Betterect, who are specialists in the fabricating and erecting of all types of industrial and process equipment — with safety and quality always top-of-mind — gave us the confidence to allow their input into the fabrication modelling. Betterect’s methodologies removed the complexity of the fabrication process, streamlining it and cutting down on the lead times, and costs,” comments Pieter Pretorius, project manager procurement, FLSmidth.
In contrast to fabrication methods where tank sections are welded together during site installation, a bolted thickener design allows for the thickeners’ modular sections to be bolted together on site, thus allowing for significantly smaller, less skilled, installation crews which can complete the installation in a much shorter duration with completely accurate alignment and a perfect fit.
The modular sections will be transported to site and bolted together in situ. A benefit of bolted sections is that no ‘hot work’ is required on site, and the assembly process is much safer as a result. As a result, erection and assembly take about three weeks compared with the traditional welded thickener process. This translates into an overall project saving of approximately 30% compared to a traditional welded thickener supply and installation project,” Skjoldhammer noted.
“One of the greatest challenges was ensuring that the very large welded modular sections – once bolted together – are aligned with and bolted to their adjoining sections with mathematical precision – working to extremely tight tolerances of 1mm over as much as 25 metres. Any deviation, even that of a millimetre within the flanges, over the massive surface area, would not have been acceptable,” Skjoldhammer explained.
Pretorius points out that thanks to Betterect’s unique fabrication process, fabrication time on this project was significantly reduced. “Fabricating a thickener of these dimensions normally takes 16 to 20 weeks – but thanks to their unique process, Betterect’s team completed the task in record time.”
“These massive thickeners were precisely engineered and designed to ensure precision alignment of the flanges, resulting in a perfect fit – much like the relationship we have with FLSmidth,” Skjoldhammer concluded.