Slotted steel pipes (slotted liners), as widely used for oil exploration and production, represent a significant heavy metal cutting application that is currently serviced by CO2 lasers but may soon switch to kilowatt fiber lasers.Slotted liners are heavy gauge (10 mm wall thickness) steel pipes fabricated in sections up to 12 meters in length. Up to 10,000 slots – often with a precise keystone profile – must be cut through the wall of each section so that the pipe acts as a sieve in the well to block sand sediments and other debris from the extracted oil. Slab discharge CO2 lasers such as the Coherent DC 030 have been the tools of choice for cutting the slots, particularly those requiring a precise keystone profile that could not be readily cut mechanically. In this whitepaper, we examine this heavy metal cutting application and see why kilowatt class fiber lasers such as the Coherent HighLight® FL series are starting to penetrate this market.