The spiral drill collar are made of 4145H modified chromium-molybdenum alloy steel according to API Spec 7 and aSY/T 5144 . All threads can be phosphated,copperised or cold worked. All threads are machined with CNC Lathes-Double-Shouldered and a special thread, the max diameter of spiral drill collar is 14 inch.

Out diamete: 3 7/8"~ 11"(inch)

Depth of cut: 4.0 ~ 11.9 (mm)

Pitch: 914~2037(mm)