DIFF Subgroup
E21B 17/22 Rods or pipes with helical structure
Introduced: January 1980
Full Title
Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Casings; Tubings > Rods or pipes with helical structure
No child classifications to compare. This is a leaf node in both IPC and CPC.