Induction Heating of a Carbon Steel Pipe for Epoxy Curing

A manufacturer supplying parts and components to the Oil & Gas Industry has requested help from our team to replace a flame/gas furnace adhesive curing process with induction heating technology, which will allow them to increase productivity and be able to perform the curing process onsite. Their application is to heat carbon steel pipes with OD ranging from 100mm to 180 mm (3.9 – 7 inch) and wall thickness 10-20mm (0.39-0.78 inch). There is a carbon composite part placed on the external wall of the pipe. The goal is to affix the part to the pipe using adhesive epoxy. This is achieved by heating the part to 200 °C degrees (392°F) in less than 5 mins and then keeping that temperature for 15min in order to cure the epoxy. Another requirement is that the induction system needs to be mobile and lightweight since the composite parts replacement will be done onsite. A portable, air-cooled induction heating system with a dry cable coil was offered to them.  

In order to achieve the desired production rate of 60 pieces a day/ 5 pieces per hour, we estimated that we need to use a 4kW air-cooled induction generator.  A thermal camera was used to track the changes of the temperature uniformity along the pipes. In the production condition, the temperature control will be done with a thermocouple. 

Equipment:    

We employed our UltraHeat S Air – SMT-5A to complete the process. It is the perfect induction heating solution for the purpose of this application because of its air-cooled, portable design, not requiring bulky water coolers or chillers. It also has a programable temperature profile featuring multiple steps of the ramp and hold times. Once the process is set up and pre-programmed, the operator can start a heating cycle by just pressing a button and the induction system will perform a full heating/holding cycle by itself.  

Process:  

We began the process by setting up the workpiece within the induction heating coil. To avoid damage to the dry cable coil we use a heat blanket as insulation between the pipe and the induction coil. The system was preprogrammed with 2 steps – ramp from room temperature to 200 °C degrees (392°F) as fast as possible (we were able to reach the temperature in 18 mins). Then the machine goes to step two – hold the temperature for 15 min until the epoxy is completely cured. 

Industry: Oil&Gas Industry 

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Reference Info: Application Note 3464-6597