Casing Running Tools - AutoFillâ„¢ - Patented AutoFillâ„¢ Casing Fill-Up and Circulating System fills or circulates casing as it is being run. Our casing circulator is the easiest to operate and the most convenient to maintain. Go to the resources/video page to see an animated video of the AutoFill in action. We offer training at our site in Texas as well as on-site training. We are presently servicing many of the major casing companies domestically and internationally.