1. Meeting with: API7-1, 7G &Q1 latest edition 2. Length:10 to 31 ft 3. NNC threads(interchangeable with API NC threads)

As the company who manufactures the first drill collar in CHINA, SFMC has been manufacturing drill collars for more than 30 years. All SFMC drill collars are made of AISI 4145H or AISI 4145H Modified alloy steel in accordance with API Specification 7-1,API Recommended Practice 7G and API Q1 Latest Edition.    The bores are trepanned from one direction with no mismatch. All drill collars are of Q&T full length by SFMC's own unique Power Frequency Induction Heating Treatment machine designed by SFMC, so as to ensure the Charpy "V" notch minimum impact strength of 40 ft/lb at  70°F and to guarantee the hardness from 285 to 341 BHN below the surface.

   SFMC drill collars’ lengths are from 10 to 31 feet and outside diameter are  form  3-1/8”~10”. SFMC also manufactures special Drill Collars with Spiral, Slip and Elevator recess, hardbanding. The square drill collar is available.

Size OD (in)	Standard bore (in)	Standard Connection style and size	30ft Approx. weight(kg)	31ft Approx. weight(kg)
3 1/8	1 1/4	NC23	296	306
3 1/4	1 1/4	NC23	325	336
3 1/2	1 1/2	NC26(2 3/8 IF)	358	370
4 1/8	2	NC31(2 7/8 IF)	469	485
4 1/4	2	NC31(2 7/8 IF)	509	526
4 1/2	2	NC31(2 7/8 IF)	585	605
4 3/4	2 1/4	NC35	629	650
5	2 1/4	NC38(3 1/2 IF)	716	740
5 1/4	2 1/4	NC38(3 1/2 IF)	811	838
5 1/2	2 1/4	NC38(3 1/2 IF)	905	935
5 3/4	2 1/4	NC40(4 FH)	1009	1043
6	2 1/4	NC44	1114	1151
6 1/4	2 1/4	NC46(4IF)	1224	1265
6 1/2	2 1/4	NC46(4IF)	1340	1385
6 3/4	2 1/4	NC46(4IF)	1466	1510
7	2 13/16	NC50(4 1/2IF)	1481	1530
7 1/4	2 13/16	NC50(4 1/2IF)	1607	1661
7 1/2	2 13/16	NC50(4 1/2IF)	1740	1799
7 3/4	2 13/16	NC56  6 5/8 Reg	1877	1940
8	2 13/16	NC56  6 5/8 Reg	2018	2085
8 1/4	2 13/16	6 5/8 Reg	2168	2240
8 1/2	2 13/16	6 5/8 Reg	2315	2392
8 3/4	2 13/16	6 5/8 Reg	2473	2555
9	3	NC61  7 5/8 Reg	2589	2675
9 1/4	3	NC61  7 5/8 Reg	2758	2850
9 1/2	3	7 5/8 Reg	2923	3020
9 3/4	3	NC70  7 5/8 Reg	3098	3200
10	3	NC70  7 5/8 Reg	3276	3385

9 1/4" API Drill Collar