One of the most important components of the drill string is to provide drilling pressure to the drill bit and increase the rigidity of the drill string.

product description:

Manufactured using AISI4145H chromium-molybdenum steel, the content of trace elements is effectively controlled. According to the shape and material of the drill collar, it can be divided into three forms:

1. Type A (cylindrical): It is made of common alloy steel and has a circular cross-section inside and outside.

2. Type B (spiral type): It is made of ordinary alloy steel and has a spiral grooved drill collar on its outer surface.

3. Type C (non-magnetic type): It is made of stainless alloy steel with very low magnetic permeability. The cross-section of the pipe body is round and round inside and outside.

Drill thread	Outside diameterD		the inside diameter ofd		lengthL mm	Chamfer Shoulder diameter Df mm	Reference bending strength ratio
Drill thread	mm	in	mm	in	lengthL mm	Chamfer Shoulder diameter Df mm	Reference bending strength ratio
NC31-41（27/8IF）	104.8	4 1/8	50.8	2	9150	100.4	2.43：1
NC35-47	120.7	4 3/4	50.8	2	9150	114.7	2.58：1
NC38-50（31/2IF）	127.0	5	57.2	2 1/4	9150	121.0	2.38：1
NC44-60	152.4	6	57.2	2 1/4	9150或9450	144.5	2.49：1
NC44-60	152.4	6	71.4	2 13/16	9150或9450	144.5	2.84：1
NC44-62	158.8	61/4	57.2	2 1/4	9150或9450	149.2	2.91：1
NC46-62（4IF）	158.8	61/4	71.4	2 13/16	9150或9450	150.0	2.63：1
NC46-65（4IF）	165.1	61/2	57.2	2 1/4	9150或9450	154.8	2.76：1
NC46-65（4IF）	165.1	61/2	71.4	2 13/16	9150或9450	154.8	3.05：1
NC46-67（4IF）	171.4	63/4	57.2	2 1/4	9150或9450	159.5	3.18：1
NC50-67（41/2IF）	171.4	63/4	71.4	2 13/16	9150或9450	159.5	2.37：1
NC50-70（41/2IF）	177.8	7	57.2	2 1/4	9150或9450	164.7	2.54：1
NC50-70（41/2IF）	177.8	7	71.4	2 13/16	9150或9450	164.7	2.73：1
NC50-72（41/2IF）	184.2	71/4	71.4	2 13/16	9150或9450	169.5	3.12：1
NC56-77	196.8	73/4	71.4	2 13/16	9150或9450	185.3	2.70：1
NC56-80	203.2	8	71.4	2 13/16	9150或9450	190.1	3.02：1
65/xREG	209.6	81/4	71.4	2 13/16	9150或9450	195.7	2.93：1
NC61-90	228.6	9	71.4	2 13/16	9150或9450	212.7	3.17：1

Drill collar