TPT September 2023

ARTICLE

Thermatool Corp

Precise process control toward automation in HF tube and pipe welding By Olexandra Tupalo, manager, Thermatool

In the modern day, marked by labour shortages and widespread retirements of skilled operators, the time to record and store proven process recipes has arrived. For tube and pipe producers hyper-competitive markets are unforgiving regarding delivery delays related to employee turnover or lack of new operator training. Automation techniques involve using technology and software like real-time monitoring, data analysis and feedback/control loops to optimise process parameters and enhance overall system performance. Automation and data analytics can also be used for predictive maintenance. Data and machine learning can be leveraged to reduce downtime by proactively predicting required maintenance. The goal of precise HF welding process control is to eliminate variability caused by manual adjustments by using advanced automated process control strategies. This is done by incorporating automation technologies such as sensors, actuators, transducers and microcontrollers to provide data to characterise the process. By combining these technology tools with software, precise process control systems can constantly monitor process variables, make real-time adjustments and adapt to changing conditions. Automation of the HF welding process does not eliminate the need for operators. Instead, it assists them in producing top quality products efficiently and consistently. With automation, operators can reduce their workload and concentrate on other areas of the tube mill where they can add the most value. Since Thermatool’s HAZControl™ Technology HF welder platform was introduced over ten years ago, a greater emphasis on optimising, controlling and data-logging process parameters has become a reality for tube and pipe producers. Big improvements in process efficiency have resulted from precise HF weld heat input control in the HF welding process. Thermatool’s HAZControl™ technology welder has the ability to select, stabilise and adjust frequency and HF weld power in ±1-kHz and 1-kW increments, allowing precise HF weld heat input control during welding. With these finely tuned process control adjustments, it is now possible to achieve precise and repeatable results when HF welding different alloy chemistries, advanced steels and coated materials on one mill with varying diameter-to-wall thickness ratios. The innovative software (Figure 2) uses a process window format to help an operator optimise power and frequency settings.

Driven by more stringent product specifications and increasing demands on product quality, precise process control in HF welding (see Fig.1) has become imperative in the development and operation of modern tube and pipe production systems. It is crucial that each tube or pipe made in the mill is of the same high quality. To ensure repeatable and reproducible product performance, while maintaining high yields, process automation plays a vital role. Not all tube and pipe mills are in a position to achieve world-class HF welding process control. In the tube and pipe industry, precise HF welding process control, combined with automation, can lead to several benefits, including increased productivity, reduced energy consumption, improved product quality, high yield and reduced scrap. By eliminating human error, statistical quality levels are increased. Automated processes allow the operator to run closer to optimal conditions at all times, resulting in increased efficiency and cost savings. The way process automation is implemented can vary depending on the industry. Generally, automated process control tools leverage the most skilled operator’s knowledge and institutionalised process knowledge.

Figure 1: HF welding process

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SEPTEMBER 2023