Preperforated tubing is produced by forming a perforation in flat strip of raw material, forming a hollow, cylindrical tube from the flat strip, and placing a removable plug into the perforation, so as to form a fluid-tight seal. A sealing element may be placed into the perforation. The perforation may comprise a hole, into which first and second countersinks may be formed. The sealing element may be placed into the first countersink, and the plug may be placed through the countersinks and the hole, such that the plug's body fills the hole and the plug's head fits within the second countersink.