1. General Information of Non-Magnetic Drill Collars

1. Non-magnetic drill collars are generally manufactured in accordance with the APL7-1 standard. Their length is usually 30FT or 31FT, which is equivalent to 9150mm or 9450mm.
2. Classified by shape, they can be divided into the following types:
   • Non-magnetic drill collars (smooth surface, standard length)
   • Non-magnetic spiral drill collars (with spiral grooves carved on the outer surface)
   • Non-magnetic pressure-bearing drill pipes (with inconsistent outer diameters and steps)
   • Non-magnetic pup joints (short drill collars with different lengths)

2. Detailed Parameters of Non-Magnetic Drill Collars

2.1 Parameter Description

• Connection Code (ab): Used to identify the connection specification and model of the drill collar with other components.
• Drill Collar Serial Number & Outer Diameter (D): The outer diameter of the drill collar, in mm.
• Inner Hole (d): The diameter of the inner hole of the drill collar, in mm, with a tolerance of +1.59mm and -0mm.
• Length (L): The actual length of the drill collar, in m, with a tolerance of ±152.4mm.
• Chamfer Diameter: The diameter of the chamfer at the end of the drill collar. The unit is not marked, and the tolerance is ±0.4.
• Reference Bending Strength Ratio (BSR): A reference ratio for measuring the bending resistance of the drill collar, in the format of “value:1″.

2.2 Detailed Parameter Table of Non-Magnetic Drill Collars