Steinmüller Africa, a leader in high-pressure steam generation equipment, alongside engineering consultants eNtsa, has successfully pioneered the use of rotary friction welding for the fabrication of headers for high-pressure water heater boiler units at Tutuka Power Station in Mpumalanga. This marks a significant first for the industry, utilizing an innovative combination of rotary friction welding and friction hydro-pillar processing (FHPP).
The teams employed this hybrid technique to attach 448 heat exchanger nozzles to each of the four high-pressure headers, which are crucial for the final assembly of the heat exchangers. The new approach was developed as a more effective alternative to the traditional submerged arc welding method, which had initially led to defects in the first four headers.
Friedrich Schwim, senior welding engineer at Steinmüller Africa, explained that precise nozzle fittings are essential for proper tube-nozzle welds. The defects found in the initial submerged arc welds were addressed by using the FHPP and rotary friction welding hybrid, ultimately ensuring the headers met industry standards.
Defect-Free Welds
“After refining the submerged arc welding process, the headers still needed repairs. The hybrid application of FHPP and rotary friction welding delivered a 100% defect-free result,” Schwim remarked. The new welding method offers several advantages, including minimal distortion in nozzle orientation, automated processes ensuring uniform welds, 75% reduced welding time compared to submerged arc welding, and no increase in manufacturing costs.
Introducing WeldCore Technology
Central to the new welding technique is WeldCore, a novel method involving the removal of a cylindrical metallurgical sample from the pipe wall, followed by repairs using taper friction hydro-pillar processing. This innovation reduces the risk of catastrophic failure and enhances uptime, offering significant cost savings for power stations.
Schwim noted that although various friction welding technologies exist, this specific application had never been used before in the industry. The successful development of the process was the result of Steinmüller Africa’s collaboration with eNtsa, whose expertise in FHPP formed the basis for the technique’s application and subsequent approval.
Industry Applications and Intellectual Property
This innovative welding method has broad applications, particularly in industries such as petrochemical, nuclear, and power generation, where nozzles must be welded to pipes for a forged-like bond. It now forms part of the intellectual property held by Steinmüller Africa and eNtsa, with the two companies being the only ones globally to introduce this technique for this specific application.
eNtsa provided the necessary welding technology, machines, and process expertise, while Steinmüller Africa supplied the welding technical knowledge, compliance requirements, and final machining of the welds. eNtsa served as Steinmüller Africa’s sub-contractor under the company’s ISO 3834-2 quality certification for the duration of the project.
Schwim concluded, “We took full responsibility for the welding process and provided the necessary technology for the final machining and post-weld heat treatment, successfully bringing the project to fruition.”
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