In 2016 Steinmüller Africa completed a planned maintenance project for state-owned national oil company PetroSA’s Mossel Bay-based Gas-To-Liquids refinery, in the Western Cape. Steinmüller Africa Welding Operations Manager Morne Kidson explained that the scope of work involved replacing the Synthol Reactor internal coil U section, and structurally replacing and welding the pipe components. The outside diameters of the pipes varied from 40 mm to 90 mm with the wall thickness varying between 3 mm and 25 mm.

Divisional Manager, Leon Olivier, explains that the Vaal workshop services Sasol Secunda during their shutdowns. “We maintain the La – Mont Boiler at their Nitric Acid plant, which entails boiler-making plate work and welding pressure parts and non-pressure parts, as well as the supply of fabricated stainless steel plates at our workshop in Sasolburg Free State,” he added.

Additionally, Olivier noted that Steinmüller Africa is an original equipment manufacturer (OEM) for various state-owned power utility Eskom boilers, and has ongoing boiler and high-pressure piping maintenance service contracts at 11 coal-fired power stations. Kidson highlights the increasing demand for explosive welding technology applications during the maintenance of high-pressure heat exchangers at power stations. “Explosive welding is used to fuse tubes to tube plates or headers in high-pressure heat exchangers. It is performed when a tube is impelled against the tube plate material using the energy from an explosive discharge. In the process, expansion and fusion occur in a high energy rate impact,” Kidson explains.

The ageing coal-fired power stations, such as Kriel and Arnot, in Mpumalanga, had several heat exchangers that need to be refurbished/replaced. They weigh several tons and have up to several thousand tubes that need to be either plugged during maintenance or replaced during refurbishment. “Since the traditional welding methods are time-consuming, explosive welding, with a weld metal travel speed of more than 8 000 m/s, reduces welding time, plant downtime and relative repair costs. It also achieves a weld that is expanded, fused and sound,” Kidson says.

Explosive welding is also suitable for welding components of different metals, as well as for welding dissimilar metals, such as carbon steel to stainless steel and stainless steel to titanium. “Steinmüller can apply the process to manufacturing in workshops, or in-situ at the power stations,” Kidson emphasises. The explosive welding technology was mostly applied on in-situ heat exchanger tube plugging. Steinmüller is the first company worldwide to manufacture a brand new heat exchanger from scratch using the explosive technology. It is important to note that the process actually fuses the two materials into one homogenous material, ensuring that the fusion line is not detectable through a microscope or etching.

Although Steinmüller Africa originally introduced explosive welding to Eskom in 2010 under licence from TEI, it remained the only company in South Africa qualified and approved to perform explosive welding for the power generation sector.

Innovation is one of Steinmüller’s values, and we are constantly evaluating the market for opportunities. The company is 60 years old and, therefore, has to continually evolve. It is vital to keep abreast of new innovations and technologies, as this allows for the company to anticipate end-user needs.

As the welding sector continues to grow, South Africa’s ventures into the adherence of reduction of carbon emissions in the production of energy, means there are substantial opportunities in the renewable energy market.