Naturally, each drill site requirement or customer preference will cause variations. The following list is only offered as a general guide for pipe selection.
All pipe is to be made of a long hole, surrounded by metal or plastic, centered around the hole.
All pipe is to be holed throughout the entire length. Do not use holes of different length than the pipe. Othervise the hole will be on the outside. All pipe is to be supplied with nothing in the hole, so that water, steam or other stuff can be put inside at a later date. All pipe should be supplied without rust.