Resumen del autor, extraído del trabajo. This paper describes the translation of the science of hot welding and hot tapping of in-service pipelines into commercial practice and commercial value. It outlines the advancements that TransCanada PipeLines Ltd. (TransCanada) has made in hot tap connections over 40 years of researching, developing and applying in-service welding and patented hot tap connection procedures on the largest natural gas transmission system in North America. The applied science of hot tap connections has provided significant commercial value to TransCanada and its affiliates as they have expanded and maintained their systems. Installation costs, throughput losses, service interruptions and greenhouse gas emissions have all been substantially reduced or avoided. Over 800 large diameter and thousands of smaller diameter permanent leak free hot tap connections have been installed over the course of 40 years without incident on the TransCanada mainline system. Connections have been made under full flow conditions on carrier pipe diameters of 50 DN to 1219 DN, wall thicknesses a minimum of 4.8mm and operating pressures of 6100 kPa to 10,000 kPa. Through its subsidiary, TransCanada Hot Taps Ltd., TransCanada is now making this technology commercially available to pipeline operators worldwide.