DRILL COLLARS

Standard :API SPEC 7-1
Steel grade:AISI 4145H
Sizes:3 1/8" -- 11"
Connected Type:NC, IF, REG
Length:30 – 31 ft ± 6 ft.
Type of design:（1）plain;（2） with a recess of the elevator; （3） with a recess of the elevator and power slips; （4） spiral and a wide range of type mixtures.
Description
Drill collar as one component of a drill string is extremely industrial tubulars used to drill into ground to provides weight on bit for drilling. It is used to conjunction with drill pipe. There are slick and spiral grooved types mainly. Our manufacturing process is certified to API spec 7-1. The drill collar is made of AISI 4145 H or 4145 H Modified alloy steel. Bores are trepanned from one direction with no mismatch. All drill collars are heat-treated with hardness within 285 to 341 BHN, which are guaranteed one inch below the surface of the pipe.

Non-magnetic drill collars offer strength and hardness while preventing magnetic interference that may impair accuracy of magnetic surveys. It is manufactured from special steel material with low permeability, high mechanical properties and superior resistance to corrosion cracking.
Specifications
We supply slick drill collars, spiral drill collars and non-magnetic drill collars; their sizes are from 3-1/8 to 11 inches. Besides the drill collars in the table below, we can supply other drill collars at customers’ request.
 

Standard Sizes, Bores, and Connections

Drill Collar Conn. Size & Type	Min. OD	Bore	Length	Bending Strength Ratio***	Drill Collar Wt.
	(in.)	(in.)	(ft.)		(lb.)
NC 26 (2-3/8 IF)	3-1/2	1-1/2	30	2.42:1	801
NC 31 (2-7/8 IF)	4-1/8	2	30	2.43:1	1041
NC 38 (3-1/2 IF)	4-3/4	2-1/4	31	1.85:1	1451
NC 38 (3-1/2 IF)	5	2-1/4	31	2.38:1	1652
NC 44	6	2-1/4	31	2.49:1	2561
NC 44	6	2-13/16	31	2.84:1	2353
NC 44	6-1/4	2-1/4	31	2.91:1	2806
NC 46 (4 IF)	6-1/4	2-13/16	31	2.63:1	2598
NC 46 (4 IF)	6-1/2	2-1/4	31	2.76:1	3085
NC 46 (4 IF)	6-1/2	2-13/16	31	3.05:1	2877
NC 46 (4 IF)	6-3/4	2-1/4	31	3.18:1	3364
NC 50 (4-1/2 IF)	7	2-1/4	31	2.54:1	3643
NC 50 (4-1/2 IF)	7	2-13/16	31	2.73:1	3434
NC 50 (4-1/2 IF)	7-1/4	2-13/16	31	3.12:1	3714
NC 56	8	2-13/16	31	3.02:1	4675
6-5/8 REG.	8	2-13/16	31	2.60:1	4675
6-5/8 REG.	8-1/4	2-13/16	31	2.93:1	5016
7-5/8 REG.	9-1/2	3	31	2.81:1	6727
7-5/8 REG.**	9-3/4	3	31	3.09:1	7130
8-5/8 REG.**	11	3	30	2.78:1	8970
** Low torque face *** Ratio of box to pin section modulus – See API RP7G for details Note: Other sizes and connections are available as well as any other optional features listed

 

Mechanical Property
TTT		Yield strength 0.2Mpa	Tensile strength b Mpa	Elongation 4%	Hardness(Brinell)	IMPACT VALUE(CHAPPY-V)
mm	in inch
79.4-171.4	3 1/8-6 3/4	≥ 758	≥ 965	≥ 13	285-341	≥ 54
177.8-279.4	7-11	≥ 689