Drill Collar is mainly used to provide bit weight to drill bit so that drill pipe is in tension. Especially drill collar can keep drill bit centralized and hole track by large rigidity

Drill Collar Number	O.D.		I.D.		Length (mm)	Bevel Diameter	Ref bend g Strength ratio
	(mm)	(in)	(mm)	(in)
NC23-31	79.4	3 1/8	31.8	1 1/2	9150	76.2	2.57:1
NC26-35(2 3/8 IF)	88.9	3 1/2	38.1	1 1/2	9150	82.9	2.42:1
NC31-41(2 7/8 IF)	104.8	4 1/8	50.8	2	9150	100.4	2.43:1
NC35-47	120.6	4 3/4	50.8	2	9150	114.7	2.58:1
NC38-50(3 1/2 IF)	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 & 9450	144.5	2.49:1
NC44-60	152.4	6	71.4	2 13/16	9150 & 9450	144.5	2.84:1
NC44-62	158.8	6 1/4	57.2	2 1/4	9150 & 9450	149.2	2.91:1
NC46-62(4IF)	158.8	6 1/4	71.4	2 13/16	9150 & 9450	150.0	2.63:1
NC46-65(4IF)	165.1	6 1/2	57.2	2 1/4	9150 & 9450	154.8	2.76:1
NC46-65(4IF)	165.1	6 1/2	71.4	2 13/16	9150 & 9450	154.8	3.05:1
NC46-67(4IF)	171.4	6 3/4	57.2	2 1/4	9150 & 9450	159.5	3.18:1
NC50-67(4 1/2 IF)	171.4	6 3/4	71.4	2 13/16	9150 & 9450	159.5	2.37:1
NC50-70(4 1/2 IF)	177.8	7	57.2	2 1/4	9150 & 9450	164.7	2.54:1
NC50-70(4 1/2 IF)	177.8	7	71.4	2 13/16	9150 & 9450	164.7	2.73:1
NC50-72(4 1/2 IF)	184.2	7 1/4	71.4	2 13/16	9150 & 9450	169.5	3.12:1
NC56-77	196.8	7 3/4	71.4	2 13/16	9150 & 9450	185.3	2.70:1
NC56-80	203.2	8	71.4	2 13/16	9150 & 9450	190.1	3.02:1
6 5/8 REG	209.6	8 1/4	71.4	2 13/16	9150 & 9450	195.7	2.93:1
NC61-90	228.6	9	71.4	2 13/16	9150 & 9450	212.6	3.17:1
7 5/8 REG	241.3	9 1/2	76.2	3	9150 & 9450	223.8	2.81:1
NC70-97	247.6	9 3/4	76.2	3	9150 & 9450	232.8	2.57:1
NC70-100	254	10	76.2	3	9150 & 9450	237.3	2.81:1
8 5/8 REG	279.4	11	76.2	3	9150 & 9450	266.7	2.84:1