21. Behind this would be a selection of drill collars and Heavy Weight Drill Pipe ( HWDP ). 22. No water rushed up, and the miners quickly tapped on the drill pipe to signal their survival. 23. To "'make a connection "'is to add another segment of drill pipe onto the top the drill string. 24. The company makes drill pipe , casing and tubing for oil wells and pumping units used on offshore wells. 25. The drill pipe operations were regrouped under the name VAM Drilling, and in 2013 renamed Vallourec Drilling Products. 26. Electronic instrumentation similar to the spherometer in design are modified at inspection plants for casing, tubing, and drill pipe . 27. The process of inspections are designed to remove weakened drill pipe , so that pipe will not fracture during drilling. 28. Extracted through the long drill pipe will be cores of rocky material some 2 inches wide and 30 feet long. 29. At first, loggers had to run their tools somehow attached to the drill pipe if the well was not vertical. 30. In modern rotary drilling, mud is circulated down the drill pipe and back up the well bore to the surface.
