Considerations for induction quench and temper of tubular products with upset ends: A case study of API 5CT L80 and P110 casing and tubing

Quench and tempering heat treating operations for tubular products are relying more on induction equipment.  The reasons for this can be traced to the lower energy costs for operating induction equipment compared to gas furnaces and the greater flexibility that the induction lines offer compared to their furnace counterparts in regards to recipe control and product mix.  However, there are special considerations for induction heat treating equipment and the induction coils for these operations.  This paper reports on the design and operation of a new induction heat treating line for API 5CT grade L80 and P110 casing and tubing with upset ends.  Upset ends pose special technical challenges for induction heating; the generation of a uniform temperature distribution relies heavily on proper coil design as well as line layout and heating time.  Simulations of induction heating have provided predictions of heating profiles, and on-the-line testing allowed recipe refinement and validation of simulation models.  Results from this case study help to increase confidence in this heat treating process as well as create a general induction heating line layout for future applications.