Induction pre-heating prior hot forming boosts productivity

Application: Pre-heating prior hot forming

Industry: Oil & Gas Industry

Application Objectives:

A new induction heating user in the Oil and Gas Industry was searching to replace old gas preheating technology for hot forming of carbon steel shaft to improve the quality and productivity of their process. Proper pre-heating phase before forming is crucial for reaching high quality and meeting the highest standards in metal forming. This is why UltraFlex was selected as the preferred partner for the customer’s research.

Our task was to calculate and simulate the required power and time first to prove the process is feasible and then to best optimize the hot roll forming process for steel (E253) pipe s with an outer diameter of 174 mm and a thickness of 6 mm. Task was tough, but not impossible. From current processing of the pipe detail within 3,5 hours with gas heating on 400 ^oC UltraFlex managed to redesign the whole process down to approximately 25 to 30 min with induction heating temperature up do 800 ^oC. Read till the end to see how

Equipment: Smart Power (125kW) 6PA + Custom coil

Materials: Steel (CS E235) Pipe (Shaft)

Key Parameters:

• Heated zone – 801 mm zone
• Max Temperature: 800 ^oC
• Duty Cycle: Continuous

Process:

Based on the client’s information and video, we estimated that the pipe moves at a speed of approximately 7 mm/s. This speed implies that heating a 150 mm section of the pipe in a stationary state would take about 20 seconds to reach 800°C. We began our analysis with software-based simulations, considering that once the temperature surpasses the Curie point, the efficiency of the coil decreases.

During the test with the 174 mm pipe, we observed a temperature difference of 40-50°C between the channels. For the 90-second test, we achieved a steady state of 800°C. However, with a 210 mm high coil, this temperature needs to be reached in 30 seconds. Achieving this is possible with more modules in Smart Power and by adjusting the tap settings on transformers. Our simulations showed the heating expectations during movement at 7.7 mm/s.

In the first test, we heated a formed pipe with an outer diameter of 173 mm using the Smart Power 100 kW power supply model and the HSP-100 W heat station model. A custom coil was used to achieve the target temperature of 800°C. The heat cycle time was set to 90 seconds, with the power ranging from 40 to 90 kW. The set point was regulated at 90% by current.

In the second test, we heated both formed and unformed pipes with an outer diameter of 173 mm using the Smart Power 125 kW 6PA power supply model and the HSP-200 M heat station model. The test coil used was the 1ASM-9100-8974-00-A01. The target temperature remained at 800°C, but the heat cycle time was extended to 120 seconds. The power ranged from 54 kW up to 125 kW in the first part of the test and from 43 kW up to 125 kW in the second part.

In summary, the process involved careful estimation and simulation to optimize the heating of steel pipes using induction heating. The tests demonstrated that achieving a steady state of 800°C within the required time frame is feasible with the right equipment and settings. The detailed parameters and observations from the tests provided valuable insights into the efficiency and effectiveness of the induction heating process for hot roll forming in the oil and gas industry.

Results and Conclusions:

Maintaining a steady state of 800°C for 30 seconds is crucial to ensure the detail holds this temperature during movement. Initial heating of the pipe is straightforward, but uniform heating becomes challenging after a few passes. Temperature at the dents of the geometry is significantly lower than at the bulges, necessitating slower movement for consistent heating. Efficiency and induced power drop drastically beyond the Curie point, so the system should be set to an average power close to 120 kW, with a reserve of power to maintain efficiency. We recommend a 160 kW Smart Power system with a custom coil, flex leads, and chiller. The project was successfully completed with UltraFlex’s team closely supporting the customer throughout the integration phase, addressing all concerns and ensuring optimal process integration. Installation was not only supervised by UltraFlex engineering teams on site, but they practically went step by step through all the process integration together with the customer`s team, to ensure final and best fine tuning.

Reference Info: AR 3464-8883

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