Drilling collar

Drill collars(Type A,B andC)are manufactured according to API and SY/T standards .Drill Collars (Type A and B) are made of 4145H chromium molybdenum alloy steel ,chemical composition and residual elements are well controlled.
Drill collars Type c (non-magnetic)are made from low carbon austenitic alloy abtained by combining a proprietary chemical anylysis and a rotary hammer forging process with low magnetic permeability excellent machineability.
Each drill collar is fully inspected by internal inspection dept.All data obtained are recorded on the inspection certificate furnished with eath drill collar.
API monogram ,serial number , OD ,ID ,type and size of connections are stamped on recessed mill flats.
Drill collars are available in lengths from 10 to 31 feet and outside diameter from 3 1/8 to 11

Collar Thread	Outside DiameterD		Inside Diameter d		Length L mm	Ledge Chamfer Diameter Df mm	Reference Bending Strength Ratio
	mm	in	mm	in
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	9150or9450	144.5	2.49:1
NC44-60	152.4	6	71.4	2 13/16	9150or9450	144.5	2.84:1
NC44-62	158.8	61/4	57.2	2 1/4	9150or9450	149.2	2.91:1
NC46-62(4IF)	158.8	61/4	71.4	2 13/16	9150or9450	150.0	2.63:1
NC46-65(4IF)	165.1	61/2	57.2	2 1/4	9150or9450	154.8	2.76:1
NC46-65(4IF)	165.1	61/2	71.4	2 13/16	9150or9450	154.8	3.05:1
NC46-67(4IF)	171.4	63/4	57.2	2 1/4	9150or9450	159.5	3.18:1
NC50-67(41/2IF)	171.4	63/4	71.4	2 13/16	9150or9450	159.5	2.37:1
NC50-70(41/2IF)	177.8	7	57.2	2 1/4	9150or9450	164.7	2.54:1
NC50-70(41/2IF)	177.8	7	71.4	2 13/16	9150or9450	164.7	2.73:1
NC50-72(41/2IF)	184.2	71/4	71.4	2 13/16	9150or9450	169.5	3.12:1
NC56-77	196.8	73/4	71.4	2 13/16	9150or9450	185.3	2.70:1
NC56-80	203.2	8	71.4	2 13/16	9150or9450	190.1	3.02:1
65/xREG	209.6	81/4	71.4	2 13/16	9150or9450	195.7	2.93:1
NC61-90	228.6	9	71.4	2 13/16	9150or9450	212.7	3.17:1